Jan 13, 2021
Paul J. Wang:
Welcome to the monthly podcast On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr. Paul Wang, editor-in-chief with some of the key highlights from this month's issue.
In our first paper, Danielle Haanschoten, Hein Wellens and Associates aim to examine survival benefit of prophylactic implantable cardioversion defibrillator (ICD) implantation in early selected high-risk patients with primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). A randomized, multicenter, controlled trial compared ICD versus conventional medical therapy in high-risk primary PCI patients based on one of the following factors: Left ventricular ejection fraction (LVF) less than 30% within four days of STEMI, primary ventricular fibrillation, Killip class 2 or greater and/or TEMI flow less than three after PCI. ICD was implanted 30 to 60 days after MI, myocardial infarction, primary endpoint was all cause mortality three years of follow-up. The trial was prematurely ended after inclusion of 266 patients, 38% of the calculated sample size. Additional survival assessments was performed in February 2019 for the primary endpoint. A total of 266 patients, 78.2% male with a mean age of 60.8 years were enrolled. 131 were randomized to the ICD arm and 135 patients to the control arm. All cause mortality was significantly lower in the ICD group, five versus 13, hazard ratio of 0.37 after three years follow-up. Appropriate ICD therapy occurred in nine patients at three years follow-up, 5 within the first eight months after implantation. After median long-term follow-up of nine years, total mortality (18% versus 38%, hazard ratio of 0.58) and cardiac mortality (hazard ratio of 0.52) was significantly lower in the ICD group. Non-cardiac death was not significantly different between the groups. LVEF increased 10% or more in the 46.5% of patients during follow-up and the extent of improvement was similar in both study groups. The authors concluded that in this prematurely terminated and thus underpowered randomized trial early prophylactic ICD implantation demonstrated lower total and cardiac mortality in high-risk STEMI patients treated with primary PCI.
In our next paper Felipe Bisbal, Eva Benito and Associates aim to test the efficacy of ablating, cardiac magnetic resonance, CMR detected atrial fibrosis plus pulmonary vein isolation (PVI). This was an open label, parallel group, randomized controlled trial. Patients with symptomatic drug refractory AF paroxysmal or persistent undergoing first or repeat ablation were randomized one-to-one basis to receive PVI plus CMR-guided fibrosis ablation, the CMR group or PVI alone, the PVI alone group. The primary endpoint was a rate of recurrence greater than 30 seconds at 12 months of follow-up using a 12-lead ECG and Holter monitoring at 3, 6 and 12 months. The analysis was conducted by intention to treat. In total 155 patients, 71% male, age 59, CHADS2-VASc 1.3, 54% paroxysmal AF were allocated to the PVI group alone (n=76) or CMR group(n=79). First ablation was performed in 80% and 71% in the PVI alone and CMR groups respectively. The mean atrial fibrosis burden was 12%, only approximately 50% of patients had fibrosis outside the pulmonary vein area. 100% and 99% of patients received the assigned intervention in the PVI alone and CMR group. Primary outcome was achieved in 21 patients (27.6%) in the PVI alone group and 22 patients (27.8%) in the CMR group (Odds ratio 0.01, P=0.976). There was no differences in the rate of adverse events, three in the CMR group and two in the PVI alone group. The authors concluded that a pragmatic ablation approach targeting CMR detected atrial fibrosis plus PVI was not more effective than PVI alone in an unselected population undergoing AF ablation with low fibrosis burden.
In the next paper, Vivek Reddy and Associates tested a novel neuromodulation therapy of stimulation of epicardial cardiac nerves passing along the posterior surface of the right pulmonary artery. 15 subjects admitted for defibrillator implantation (ejection fraction≤35%) on standard heart failure medications were enrolled. Through femoral arterial access, high fidelity pressure catheters were placed in the left ventricle and aortic root. After electro anatomic rendering of the pulmonary artery and branches, either a circular or basket electrophysiology catheter was placed in the right pulmonary artery to allow electrical intravascular stimulation at 20 hertz, 4 ms pulse width, and less than or equal to 20 milliamperes. Changes in the maximum positive dP/dt, the dP/dtMax indicated change in ventricular contractility. Of 15 enrolled patients, five were not studied due to equipment failure or abnormal pulmonary artery anatomy. In the remaining patients dP/dtMax increased significantly by 22.6%. There was also a significant increase in maximum negative dP/dt, dP/dtMin, mean arterial pressure, systolic pressure, diastolic pressure, and left ventricular systolic pressure. There was no significant change in heart rate or left ventricular diastolic pressure. In this first-in-human study, the authors demonstrated that in humans with stable heart failure, left ventricular contractility could be accentuated without an increase in heart rate or left ventricular filling pressures.
In our next paper, Jorge Romero, Luigi Di Biase, and Associates, in their study investigated the incremental benefit of left atrial appendage electrical isolation (LAAEI) in patients undergoing catheter ablation for nonparoxysmal atrial fibrillation (AF). Propensity score-matched analysis was performed using a prospective registry database from 2010 to 2014. All patients in the LAAEI group were matched based on baseline characteristics, echocardiographic parameters, and procedural ablation techniques. Authors identified 1842 patients who underwent catheter ablation for nonparoxysmal atrial fibrillation. Propensity score matching yielded 1092 patients, 546 with LAAEI, and 546 without LAAEI. At five years follow-up, overall freedom from all arrhythmia recurrence, off-antiarrhythmic drugs, in patients who underwent LAAEI was 68.9% versus 50.2% in those who underwent standard ablation (p<0.001). Acute complication rates were similar between groups, LAAEI 1.3% and non-LAAEI 0.73% (p=0.36). At five year follow-up, 382 (70%) patients in the LAAEI group remained on oral anticoagulation versus 217 (39.7%) in the non-LAAEI group. No thromboembolic events occurred in either group on oral anticoagulation. In patients who were off oral anticoagulation, a five year follow-up, thromboembolic events occurred in 15 of 164 (9.1%) in the LAAEI group and 4 out of 329 (1.2%) in the non-LAAEI group (p<0.001). The authors concluded that at five year follow-up, LAAEI was associated with significantly higher freedom from all atrial arrhythmia recurrence in patients with persistent and long-standing persistent AF without increasing acute procedural complication rate. In patients off oral anticoagulation, there appears to be a higher risk of thromboembolic events in the LAAEI group.
In the next paper, Niraj Varma and Associates postulated that left ventricular (LV) epicardial pacing results in slowly propagating pace wave fronts effect that may limit cardiac resynchronization therapy (CRT) efficacy in patients with left ventricular (LV) enlargement using conventional biventricular or bi-V pacing and single LV pacing, but may be mitigated by LV pacing by two widely spaced sites using MultiPoint pacing (MPP) with anatomic separation (AS) of 30 millimeters or more. They tested this hypothesis in the multi-centered MPT IDE trial. Following implant, quadripolar biventricular pacing was activated in all patients (n=506). From 3 to 9 months post implant among patients with available baseline LV and diastolic volumes LVEDV measures and 188 received bi-V pacing and 43 receiving MPP-AS. Patients were dichotomized by median baselines LVEDV indexed to height. Outcomes were measured by the clinical composite score (CCS) as the primary endpoint, quality of life, left ventricular remodeling, EF greater than 5% and systolic volume decreased 10% in heart failure event or cardiovascular death. LVEDVI median was 1.4 millimeters per centimeter. Baseline characteristics differed in patients with LVEDVI greater than median versus LVEDVI less than or equal to median. Among patients with LVEDVI greater than median, bi-V was less efficacious compared to patients with LVEDVIs less than or equal to median. Clinical composite scores 65% versus 79%. In contrast, MPP-AS programming generated greater composite score response (92% versus 65%, P=0.03) and improved quality of life (31 versus -15.7, P=0.38) versus bi-V pacing with LVEDV greater than median. Reverse remodeling trended better with MPP-AS programming. When LVEDVI was greater than median, heart failure event rate increased following the three months randomization point in bi-V but no heart failure event occurred in patients with MPP-AS programming between three and six months in LVEDVI greater than median. All measured outcomes did not differ in patients receiving MPP-AS and bi-V pacing with LVEDVI less than or equal to median. The authors concluded that conventional biventricular pacing even with a quadripolar lead has reduced efficacy in patients with left ventricular enlargement however in patients with larger hearts and programmed to MPP-AS the greatest response rate was observed.
In our next paper, Chih-Min Liu, Shih-Lin Chang, Hung-Hsun Chen and Associates, applied deep learning to pre-ablation pulmonary vein computed tomography (PVCT) geometric slices to create a predictive model for non-pulmonary vein (NPV) triggers in patients with paroxysmal atrial fibrillation (PAF). They retrospectively analyzed 521 PAF patients who underwent catheter ablation of PAF. Among them, PVCT geometric slices from 358 nonrecurrent AF patients one to three millimeters interspace per slice, 20 to 200 slices per each patient, ranging from the upper border of the left atrium to the bottom of the heart, for a total of 23,683 images of slices were used in the deep learning process, the ResNet34 of the neural network, to create the predictive model of the NPV trigger. There were 298 (83.2%) of patients with only pulmonary vein (PV) triggers and 60 (16.8%) with non-PV triggers plus or minus PV triggers. The patients were randomly assigned to either training, validation, or test groups, and their data was allocated according to those datasets. The image datasets were split into training (N=17,340), validation 3491, and testing 2852 groups, which had completely independent set of patients. The accuracy of prediction in each PVCT image for non-pulmonary vein trigger was 82.4%. The sensitivity and specificity were 64.3% and 88.4%, respectively. For each patient, the accuracy of prediction for a non-pulmonary vein trigger was 88.6%. The sensitivity and specificity were 75.0% and 95.7%, respectively. The area under the curve (AUC) for each image was 0.82 and 0.88, respectively. The authors concluded that the deep learning model using pre-ablation PVCT can be applied to predict trigger origins in PAF patients receiving catheter ablation. The applications model may identify patients at a high risk for non-pulmonary vein trigger before ablation.
In our next paper, Brian Zenger and Associates aim to understand the relationship between physician social media influence and their scholarly and clinical activity. Authors identified attending US electrophysiologists on Twitter. They compared physician Twitter activity to A) scholarly publication record H-index and B) clinical volume according to CMS. The ratio observed versus expected Twitter followers, observed to expected ratio was calculated based on each scholarly K-index and clinical activity. Authors identified 284 physicians with mean Twitter age of 5.0 years and median 568 followers. They had a median of 34.5 peer-reviewed papers, 401 citations, and H-index 9. The median K-index was 0.4. The median EP procedures was 77 and E and M visits 264. The top 1% electrophysiologists for followers accounted for 20% of all followers, 70% of status updates, and a mean H-index of six versus 15 for others (P=0.3) and accounted for 1% of procedural and E and M volumes. They had a mean K-index of 21 versus 0.77 for others (P<0.0001) and clinical observed to expected follower ratio of 7.9 and 18.1 for procedures and E and M (P<0.001) each, versus others. The authors concluded the electrophysiologists who are active on Twitter with modest influence often representative of scholarly and clinical activity. However, the most influential physicians appear to have relatively modest scholarly and clinical activity.
In our next paper, Soroosh Kiani and Associates identified four explanted hearts in the context of transplant who received stereotactic body radiation therapy (SBRT) as part of an 11 patient compassionate use series at their institution. Clinical ventricular tachycardias (VTs) and CT defined target volume of SBRT were correlated to the anatomic specimen. Gross pathological, histological, and ultrastructural examination of tissue in the target area of SBRT were performed. All patients had nonischemic cardiomyopathy, and 3 had left ventricular assist devices. In all cases, patients had recurrent sustained ventricular tachycardia (VT) and had multiple failed antiarrhythmics and radiofrequency ablation. Four patients underwent five SBRT therapy sessions with 25 gray single-fraction dose delivered to the area of culprit scar. The time from SBRT to explant was 12 to 250 days. Histopathological features following radiation were comparable in all patients and were characterized by area of subendocardial necrosis surrounded by a rim of fibrosis. In one patient, the surrounding myocardium showed cytoplasmic vacuolization in myocytes and in another patchy interstitial fibrosis. Vascular changes consisted of myointimal thickening with prominence of endothelial cells. Electron microscopy (EM) of myocardium showed irregular, convoluted intercalated disc regions, loss of contractile elements with disrupted and haphazardly arranged myofibrils, and edematous mitochondria with loss of cisternae. The authors reported the first series of findings in human tissue in four patients after SBRT. Histopathological features were consistent across all four patients and were indicative of cell injury, death, and to a lesser extent fibrosis. EM demonstrated features consistent with acute injury. These specimens may provide radiobiological evidence of acute cellular injury during SBRT for VT, which may have an antiarrhythmic effect prior to the onset of fibrosis.
In our next paper, Job Verdonschot, Stephane Heymans, Mark Hazebroek and Associates in their study aimed to depict the underlying cardiac pathophysiologic process of nonresponse to cardiac resynchronization therapy (CRT) in dilated cardiomyopathy (DCM) using endomyocardial biopsies (EMB). Within the Maastricht and Innsbruck registries of DCM patients, 99 patients underwent EMB before CRT implantation, with histological quantification of fibrosis and inflammation, where inflammation was defined as greater than 14 infiltrating cells per millimeter squared. Echocardiographic left ventricular end-systolic volume (LVESV) reduction of 15% or greater after six months was defined as response to CRT. RNA was isolated from cardiac biopsies of a representative subset of responders and nonresponders; 67 patients responded (68%), whereas in 32 (32%) did not respond to CRT. Cardiac inflammation prior to implantation was negatively associated with response to CRT (25% of responders and 47% of nonresponders, odds ratio 0.3, P=0.01). EMB fibrosis did not relate to CRT response. Cardiac inflammation improved the robustness of prediction beyond well-known clinical predictors of CRT response (likelihood ratio test, P<0.001). Cardiac transcriptomic profiling of EMB reveals a strong proinflammatory and profibrotic signature in the hearts of nonresponders compared to responders. Authors concluded that cardiac inflammation along with a transcriptomic profile of high expression of combined proinflammatory and profibrotic genes are associated with a poor response to CRT in DCM patients.
In our next paper, Mohit Turagam, Daniel Musikantow, and Associates extracted data from a registry regarding consecutive patients with confirmed COVID-19 who are receiving continuous telemetric ECG monitoring and had a definitive disposition of hospital discharge or death. Between patients who died versus discharged, they compared a primary composite endpoint of cardiac arrest from ventricular tachycardia, ventricular fibrillation or bradyarrhythmias such as atrioventricular block. Among 800 COVID-19 patients at Mount Sinai Hospital with definitive dispositions, 140 patients had telemetric monitoring and either died (52) or were discharged (88); the median age was 61 years, 73% men, and ethnicity was Caucasian at 34%. Comorbidities included hypertension in 61%, coronary artery disease in 25%, ventricular arrhythmia history in 1.4%, and no significant comorbidities in 16%. Compared to discharged patients, those who had died had elevated peak troponin levels 0.27 versus 0.02 nanograms per milliliter and more primary endpoint events (17% versus 4%, P=0.01), a difference driven by tachyarrhythmias. Fatal tachyarrhythmias invariably occurred in the presence of severe metabolic imbalance, whereas atrioventricular block was largely an independent primary event. The authors concluded that hospitalized COVID-19 patients who die experience malignant cardiac arrhythmias more often than those who survive to discharge. However, these events represent a minority of cardiovascular deaths, and ventricular tachyarrhythmias are mainly associated with severe metabolic derangement.
In our next paper, Sarah Ghonim and Associates examine whether adults with repaired tetratology of Fallot (RTOF) die prematurely for ventricular tachycardia (VT) and sudden cardiac death inducible VT predicts mortality. Ventricular scar, the key substrate for VT, can be noninvasively defined with late gadolinium enhancement, cardiac magnetic resonance (CMR) but whether this relates to inducible VT is unknown. 69 consecutive RTOF patients (43 male, mean 40 years) clinically scheduled for invasive programmed VT-stimulation were prospectively recruited for prior 3D late gadolinium enhancement LGE CMR. Ventricular LGE was segmented and merged with reconstructed cardiac chambers and LGE volume was measured. VT was induced in 22 of 31 patients. Univariable predictors of inducible VT include increased RV LGE (OR 1.15), increased nonapical ventricular LV LGE (OR 1.09), older age (OR 1.6), QRS duration≥180 milliseconds (OR 3.5), history of nonsustained VT (OR 3.5), and previous clinical sustained VT (OR 12.8). Only prior sustained VT (OR 8.02) remained independent in bivariable analyses after controlling for RV LGE volume (OR 1.14) and RV LGE volume of 25 centimeter cubed had 72% sensitivity and 81% specificity for predicting inducible VT (AUC 0.81). At the extreme cutoffs for ruling-out and ruling-in inducible VT, RV LGE>10 cubic centimeters was 100% sensitive and 36 centimeters cubed was 100% specific for predicting inducible VT. Authors conclude that 3D LGE CMR defined scar burden is independently associated with inducible VT and may help refine patient selection with programmed VT-stimulation when applied to at least intermediate clinical risk cohort.
In our next paper, Moussa Saleh, the Northwell COVID-19 Research Consortium and Associates performed a comprehensive search of the electronic medical records using a proprietary python script to identify any mention of QT prolongation, ventricular tachyarrhythmias and cardiac arrest. COVID-19 positive patients that received hydroxychloroquine±azithromycin across 13 hospitals between March 1st and April 15th were included in this study. The primary outcome of torsade de pointes was observed in one (0.015%) out of 6476 hospitalized COVID-19 patients receiving hydroxychloroquine±azithromycin. 67 (1.03%) had hydroxychloroquine±azithromycin held or discontinued due to average QT prolongation of 60 milliseconds from a baseline QTc of 473.7 milliseconds to a peak QTc of 532.6 milliseconds. Of these patients, hydroxychloroquine±azithromycin were discontinued in 58 patients (86.6%) while one or more doses of therapy were held in the remaining nine (13.4%). A simplified approach to monitoring for QT prolongation arrhythmia was implemented on April 5th. There were no deaths related to the medications with the simplified monitoring approach and hydroxychloroquine exposure was reduced. The author concluded that the risk of torsade de pointes is low in hospitalized COVID-19 patients receiving hydroxychloroquine±azithromycin therapy.
In our next paper, Yoshiaki Kaneko and Associates studied 22 consecutive patients with superior fast-slow AV nodal reentrant tachycardia (AVNRT) among which 3 patients had an apparent, but not typical slow-fast AVNRT characterized by a long AH interval and tachycardia (long AH). The diagnosis of superior AV nodal reentrant tachycardia was based on the standard criteria in two patients and the occurrence of Wenckebach AV block during tachycardia, which was attributed to a block at the lower common pathway below the circuit of the AVNRT, detected owing to the lower common pathway potentials in one patient. As with typical slow-fast AVNRT, tachy-long-AH was induced after a jump in the AH interval. In contrast, typical slow-fast AVNRT fluctuation in the ventriculoatrial interval was observed during the tachy-long-AH. Ventricular overdrive pacing was unable to entrain or terminate the tachy-long-AH. Moreover, the tachy-long-AH reciprocally transited to/from superior fast-slow AVNRT spontaneously or was triggered by ventricular contractions while the atrial cycle length and EAA remained unchanged. Both tachycardias were cured by ablation at a single site in the right-side para-Hisian region of two patients and the noncoronary aortic cusp of one patient. Collectively, the essential circuit of both tachycardias was identical, and the tachy-long-AH was diagnosed as another phenotype of superior fast-slow AVNRT accompanied by sustained antegrade conduction via another bystander slow pathway breaking through the His-bundle owing to the repetitive antegrade block at the lower and common pathway, thus presenting as a long AH interval during the ongoing superior fast-slow AVNRT. The authors concluded that an unknown superior fast-slow AVNRT phenotype exists that apparently mimics the typical slow-fast AVNRT and is also an unknown subtype of apparent slow-fast AVNRT.
In our next paper, Tinuola Ajayi, Christy Remein and Associates designed and implemented a virtual atrial fibrillation (AF) Strategically Focused Research Network (SFRN) Cross-Center Fellowship program to enhance the competencies of early-stage AF basic, clinical, and population health researchers through experiential education and mentorship. The pedagogical model involves significant cross-center collaboration to produce a curriculum focused on enhancing AF scientific competencies, fostering career and professional development, and cultivating grant writing skills. Outcomes for success involved clear expectations for fellows to produce manuscripts, presentations, and for those at the appropriate career stage, grant applications. Authors evaluated the effectiveness of the fellowship model versus mixed methods formative and summative surveys. In the two years of the fellowship, fellows generally achieved productivity metrics sought by our pedagogical model, with outcomes for the 12 fellows including 50 AF-related manuscripts, 7 publications, 28 presentations, and 3 grant awards applications. Participant evaluations reported that the fellowship effectively met educational objectives. All fellows reported medium to high satisfaction with the overall fellowship, webinar content and facilitation, staff communication and support, and program organization. The authors concluded that the fellowship model represents an innovative educational strategy by providing a virtual AF training and mentoring curriculum for early career basic, clinical, and population health scientists working across multiple institutions, which is particularly valuable in the pandemic era.
In our next paper, Audrey Dionne and Associates hypothesize that atrioventricular reentrant tachycardia is common in children. Catheter ablation is increasingly used as first-line therapy with a high acute success, but recurrence during follow-up remains a concern. The aim of this study was to identify risk factors for recurrence after accessory pathway (AP) ablation. Cox proportional hazard models were used to examine the association between patient and procedural characteristics and recurrence during follow-up. In 558 accessory pathway ablation procedures, 542 (97%) were acutely successful. During a follow-up of 0.4 years, there were 42 (8%) patients with documented recurrence. On univariate analysis, early recurrence was associated with younger age, congenital heart disease, multiple accessory pathways, accessory pathway location, right sided and posteroseptal versus left sided, cryoablation versus radiofrequency (RF), empiric ablation, the lack of full power RF lesions <50 watts, RF consolidation time <90 seconds and the use of fluoroscopy without a 3D dimensional mapping system. On multivariate analysis, only multiple accessory pathways (hazard ratio 2.78) and RF consolidation time <90 seconds (hazard ratio of 4.38) remained significantly associated with early recurrence. This association remained true when analyzing subgroups by pathway location for right and left free wall accessory pathways. The authors concluded that in their institutional experience RF consolidation time < 90 seconds after ablation was associated with an increased risk of early recurrence.
In a research letter, Kevin Makati and Associates developed a hybrid epicardial endocardial procedure to address suboptimal treatment outcomes for persistent atrial fibrillation (AF) and longstanding persistent atrial fibrillation. The hybrid convergent procedure combines minimally invasive epicardial radiofrequency (RF) ablation of the left atrial posterior wall and pulmonary vein (PV) antrum with endocardial PV isolation (PVI) and has shown favorable results in achieving sinus rhythm with and without antiarrhythmic drugs including in longstanding persistent atrial fibrillation and with longer follow-up. This investigation used a retrospective analysis of 226 consecutive patients enrolled in the registry TRAC-AFib which collects data and surgical and hybrid ablation procedures. The patients underwent convergent procedures with endocardial cryothermy PVI between November 2011 and May 2018. A total of 201 patients had available follow-up after blanking period for primary effectiveness. 75% of all patients were free of ATAF or atrial tachycardia on previously ineffective antiarrhythmic drugs and 70% were free of AF, atrial flutter, atrial tachycardia off amiodarone. At last follow-up, 77% of patients were off antiarrhythmic drugs and 69% of these patients were free of atrial fibrillation, atrial flutter, or atrial tachycardia. Thus freedom from atrial fibrillation, atrial flutter or atrial tachycardia off antiarrhythmic drugs was 53%. 85% of persistent atrial fibrillation and 70% of longstanding persistent atrial fibrillation were free of atrial fibrillation, atrial flutter, atrial tachycardia with a mean 14.7 and 16.8 months follow-up. 84% of persistent AFib and 64% of longstanding atrial fibrillation patients were free of atrial fibrillation, atrial flutter, atrial tachycardia off amiodarone. This is the largest study using endocardial cryothermy in convergent procedures providing insight in the safety and effectiveness of this alternative energy source after epicardial RF ablation. Results indicate that the cryoconvergent procedure provides a promising solution for persistent atrial fibrillation and longstanding persistent atrial fibrillation evidenced by relatively low atrial fibrillation recurrence rates and marked AF burden reduction after treatment even in longstanding persistent atrial fibrillation.
In this research letter by Sergio Conti and Associates, they sought to determine the impact of various monitoring strategies and procedural success. In STAR AF II, patients with persistent AF were randomized one to four to four fashion to pulmonary vein isolation PVI alone, PVI plus complex fractionated atrial electrograms or PVI plus linear ablation. Patients were followed for 18 months with a visit ECG and 24-hour Holter at 3, 6, 9, 12, and 18 months. In addition, transtelephonic monitoring transmission was performed weekly for 18 months and whenever symptoms were reported. After initial three month blanking, recurrences were defined as any arrhythmia greater than 30 seconds. The pool procedural success rate was reported assuming five different monitoring scenarios, Holter recordings at six and 12 months (group A); Holter at three, six and 12 months (group B); Holter at three, six, nine, and 12 months (group C); Holter at three, six, nine, 12 and 18 months (group D); Holter at three, six, nine, 12, 18 months plus all transtelephonic transmissions (group E). Comparisons of procedural success obtained by each of the following scenarios was performed using Cochran's Q test. 549 patients completed the ablation and 18 month followup. Compliance with the visits with 90%, for followup Holter monitor 85%, for weekly transtelephonic monitoring 75%. The pool of success for all three aims in the study was 44% including all of the Holter recordings and transtelephonic transmissions group E. The pool of success rate for the other monitoring scenarios were as follows: Group A 73.5%, group B 64.6%, group C 62.2%, and group D 58.2%. Cochran's Q test showed a significant difference between the four screening strategies (P<0.0001). The McNemar's test showed significant difference when a sequential comparison between groups were performed (P<0.05). In this study, the authors demonstrated that more intensive post ablation monitoring leads to increased detection of AFib, increased interestingly the biggest difference seemed to occur going from twice yearly to three times a year. This substudy suggests that the guidance of the 2017 HRS consensus statement recommending a minimum of twice yearly Holter monitoring post ablation persistent AFib may not be sufficient. The study confirms that more rigorous monitoring strategy for detection of AF recurrence after atrial fibrillation will lower the procedural success rate and increase beyond twice yearly Holter monitoring in addition of transtelephonic monitoring appeared to result in numerically larger increases of AFib ascertainment.
In a research letter, Alessandro Vicentini and Associates in their study aim to investigate the relationship between baseline QTc and mortality. Authors performed retrospective analysis of ECGs of 318 patients admitted to the Policlinico San Mateo Hospital in Pavia, Italy between February 22, 2020 and April 24, 2020. Patients were defined as infected by a positive nasopharyngeal swab for COVID-19 or by clinically diagnosed infection. QT interval was mainly measured from 12-lead ECG using Bazzett's formula. The authors found that the QTc interval in COVID-19 patients is higher than expected in a normal population. They hypothesized that one of the mechanisms explaining this phenomenon is inflammatory cytokines activation which can suppress ITR in heterologous cells and myocytes resulting in prolonged repolarization. Moreover COVID-19 patients were more susceptible to pulmonary thromboembolism which is known to be linked to QT prolongation. Furthermore, prolonged QTc was found to be a strong predictor in hospital mortality with the highest risk in patients with prolonged baseline QTc and further prolongation with a value of greater than or equal to 500 milliseconds observed during hospitalization.
In a research letter, Saverio Iacopino and Associates investigated the arrhythmic complications of patients hospitalized with COVID-19 pneumonia in the intensive care unit or general medicine department at their institution between April 1 and 26, 2020. The authors collected baseline characteristics, laboratory findings, and therapy. All patients were on continuous telemetry during hospitalization. New diagnosis of atrial fibrillation (AF) lasting more than 30 seconds, atrial tachycardia (AT) lasting more than 30 seconds, sustained greater than 30 or nonsustained greater than three beats of ventricular tachycardia (VT) and symptomatic bradycardia requiring permanent cardiac pacemaker that occurred during hospitalization were verified. A daily electrocardiogram (ECG) was also analyzed to measure corrected QT interval and evaluated potential prolongation QT greater than 500 milliseconds. Continuous variables were reported as mean standard deviation. The authors found that patients with arrhythmias had higher inflammatory markers such as peak white blood counts, C-reactive protein and creatinine phosphokinase (CPK) suggesting a more extended inflammatory stress that probably also effected the cardiovascular system. In hospital mortality was also higher in these patients, 50% versus 11%. With a limited number of patients, the authors findings should be considered as preliminary observations that need to be confirmed in larger controlled studies.
In a research letter, Akira Matsumori and Associates found that circulating immunoglobulin free light chains (FLCs) were increased in mice with heart failure due to myocarditis. The authors tested their hypothesis that their differences in concentration of FLCs among patients with lone AFib who are in AFib when they took the samples, heart failure with sinus rhythm in age matched healthy volunteers. FLC kappa and lambda were assayed. Patients with amyloidosis, renal insufficiency and autoimmune disorders were excluded. FLCs have benefits because they are very stable and do not change after long-term storage and up to three freeze-thaw cycles. Separately, after amassing the lone AF (N=28), in heart failure (N=16), with sinus rhythm groups (N=110), group by propensity score using age and sex, all statistics were performed. The median concentrations of circulating FLC lambda and kappa in patients with lone AF and atrial fibrillation in sinus rhythm were significantly different from the healthy volunteer group (P<0.01). Area under the curve of the receiver operating curve showed that FLC kappa or lambda was helpful in differentiating atrial fibrillation patients from healthy volunteers.
In a special report, Timothy Markman and Associates aim to investigate the patient and procedural characteristics associated with worsening tricuspid regurgitation after right ventricular (RV) lead placement as well as a time course of these changes. The authors used a prolapse technique, a straight stylet was withdrawn several centimeters from the lead tip to create atraumatic portion that was advanced across the floor of the right atrium creating a loop which crossed the tricuspid valve. They also used a direct method, a curved stylet used to advanced the lead across the tricuspid valve. The authors identified 1599 patients who underwent first time placement of the right ventricular (RV) lead. Of these 583 met study inclusion criteria, including 105 implanted with cardiac resynchronization (CRT) devices. Baseline echocardiograms were performed 47 days prior to implantation and followup echocardiograms 249 days following implantation. By two months, the tricuspid regurgitation (TR) severity increased by mean grade of 0.8 while tricuspid severity remained unchanged over the remainder of the first year in non-CRT patients. Among CRT patients, tricuspid regurgitation progressively decreased to levels lower than pre-device implantation. In univariable ordinal logistic regression, worsening TR severity was positively associated with the prolapse technique (OR 1.49), and inversely associated with CRT implantation (OR 0.59). There was no association between ventricular pacing percentage among non-CRT patients. In multivariable ordinal logistic regression increased TR severity was positively associated with baseline pulmonary artery systolic pressure (OR 1.03) and inversely associated with CRT implantation (OR 0.43). The authors found that TR rapidly increased with a mean 0.8 grade within the first two months. TR steadily improved over the following year in CRT patients.
In a review article, Khaldoun Tarakji and Associates discuss that the field of cardiac electrophysiology has been on the cutting edge of advanced digital technology for many years. More recently, medical device development through traditional clinical trials has been supplemented by direct to consumer products with advancement of the wearables and healthcare apps. The rapid growth of innovation along with mega data generated has created challenges and opportunities. This review summarizes a regulatory landscape applications to clinical practice, opportunities for virtual clinical trials, the use of artificial intelligence to streamline, interpret data, and integration into the electronic medical records and medical practice. Preparation of the new generation of physicians, guidance and promotion by professional societies and the advancement of research in the interpretation and application of big data and the impact of digital technology and healthcare outcomes will help to advance the adoption and future of digital healthcare.
That's it for this month. We hope that you'll find the journal to be the go to place for everyone interested in the field. See you next time. This program is copyright and American Heart Association 2020.