Suneet Mittal

Transthoracic Cardioversion of Atrial Fibrillation Comparison of Rectilinear Biphasic Versus Damped Sine Wave Monophasic Shocks

BACKGROUND Clinical studies have shown that biphasic shocks are more effective than monophasic shocks for ventricular defibrillation. The purpose of this study was to compare the efficacy of a rectilinear biphasic waveform with a standard damped sine wave monophasic waveform for the transthoracic cardioversion of atrial fibrillation. METHODS AND RESULTS In this prospective, randomized, multicenter trial, patients undergoing transthoracic cardioversion of atrial fibrillation were randomized to receive either damped sine wave monophasic or rectilinear biphasic shocks. Patients randomized to the monophasic protocol (n=77) received sequential shocks of 100, 200, 300, and 360 J. Patients randomized to the biphasic protocol (n=88) received sequential shocks of 70, 120, 150, and 170 J. First-shock efficacy with the 70-J biphasic waveform (60 of 88 patients, 68%) was significantly greater than that with the 100-J monophasic waveform (16 of 77 patients, 21%, P<0.0001), and it was achieved with 50% less delivered current (11+/-1 versus 22+/-4 A, P<0.0001). Similarly, the cumulative efficacy with the biphasic waveform (83 of 88 patients, 94%) was significantly greater than that with the monophasic waveform (61 of 77 patients, 79%; P=0.005). The following 3 variables were independently associated with successful cardioversion: use of a biphasic waveform (relative risk, 4.2; 95% confidence intervals, 1.3 to 13.9; P=0.02), transthoracic impedance (relative risk, 0.64 per 10-Omega increase in impedance; 95% confidence intervals, 0.46 to 0.90; P=0.005), and duration of atrial fibrillation (relative risk, 0.97 per 30 days of atrial fibrillation; 95% confidence intervals, 0.96 to 0.99; P=0.02). CONCLUSIONS For transthoracic cardioversion of atrial fibrillation, rectilinear biphasic shocks have greater efficacy (and require less energy) than damped sine wave monophasic shocks.

A Randomized Comparison of Pulmonary Vein Isolation With Versus Without Concomitant Renal Artery Denervation in Patients With Refractory Symptomatic Atrial Fibrillation and Resistant Hypertension

OBJECTIVES The aim of this prospective randomized study was to assess the impact of renal artery denervation in patients with a history of refractory atrial fibrillation (AF) and drug-resistant hypertension who were referred for pulmonary vein isolation (PVI). BACKGROUND Hypertension is the most common cardiovascular condition responsible for the development and maintenance of AF. Treating drug-resistant hypertension with renal denervation has been reported to control blood pressure, but any effect on AF is unknown. METHODS Patients with a history of symptomatic paroxysmal or persistent AF refractory to ≥2 antiarrhythmic drugs and drug-resistant hypertension (systolic blood pressure >160 mm Hg despite triple drug therapy) were eligible for enrolment. Consenting patients were randomized to PVI only or PVI with renal artery denervation. All patients were followed ≥1 year to assess maintenance of sinus rhythm and to monitor changes in blood pressure. RESULTS Twenty-seven patients were enrolled, and 14 were randomized to PVI only, and 13 were randomized to PVI with renal artery denervation. At the end of the follow-up, significant reductions in systolic (from 181 ± 7 to 156 ± 5, p < 0.001) and diastolic blood pressure (from 97 ± 6 to 87 ± 4, p < 0.001) were observed in patients treated with PVI with renal denervation without significant change in the PVI only group. Nine of the 13 patients (69%) treated with PVI with renal denervation were AF-free at the 12-month post-ablation follow-up examination versus 4 (29%) of the 14 patients in the PVI-only group (p = 0.033). CONCLUSIONS Renal artery denervation reduces systolic and diastolic blood pressure in patients with drug-resistant hypertension and reduces AF recurrences when combined with PVI.

Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial A Randomized Trial Comparing Empirical, Echocardiography-Guided, and Algorithmic Atrioventricular Delay Programming in Cardiac Resynchronization Therapy

Background— One variable that may influence cardiac resynchronization therapy response is the programmed atrioventricular (AV) delay. The SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial prospectively randomized patients to a fixed empirical AV delay (120 milliseconds), echocardiographically optimized AV delay, or AV delay optimized with SmartDelay, an electrogram-based algorithm. Methods and Results— A total of 1014 patients (68% men; mean age, 66±11 years; mean left ventricular ejection fraction, 25±7%) who met enrollment criteria received a cardiac resynchronization therapy defibrillator, and 980 patients were randomized in a 1:1:1 ratio. All patients were programmed (DDD-60 or DDDR-60) and evaluated after implantation and 3 and 6 months later. The primary end point was left ventricular end-systolic volume. Secondary end points included New York Heart Association class, quality-of-life score, 6-minute walk distance, left ventricular end-diastolic volume, and left ventricular ejection fraction. The medians (quartiles 1 and 3) for change in left ventricular end-systolic volume at 6 months for the SmartDelay, echocardiography, and fixed arms were −21 mL (−45 and 6 mL), −19 mL (−45 and 6 mL), and −15 mL (−41 and 6 mL), respectively. No difference in improvement in left ventricular end-systolic volume at 6 months was observed between the SmartDelay and echocardiography arms (P=0.52) or the SmartDelay and fixed arms (P=0.66). Secondary end points, including structural (left ventricular end-diastolic volume and left ventricular ejection fraction) and functional (6-minute walk, quality of life, and New York Heart Association classification) measures, were not significantly different between arms. Conclusions— Neither SmartDelay nor echocardiography was superior to a fixed AV delay of 120 milliseconds. The routine use of AV optimization techniques assessed in this trial is not warranted. However, these data do not exclude possible utility in selected patients who do not respond to cardiac resynchronization therapy. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00677014.

Superior vena cava defibrillator coils make transvenous lead extraction more challenging and riskier

To the Editor: Studies have demonstrated equivalent defibrillation efficacy and all-cause mortality in patients with single and dual coil implantable cardioverter-defibrillator (ICD) leads ([1,2][1]). Despite this equivalency, the vast majority of implanted ICD leads are dual coil ([3][2]). The

Reversal of Cardiomyopathy in Patients With Repetitive Monomorphic Ventricular Ectopy Originating From the Right Ventricular Outflow Tract

Background—Tachycardia-induced cardiomyopathy caused by ventricular tachycardia is a well-defined clinical entity. Less well appreciated is whether simple ventricular ectopy can result in cardiomyopathy. We sought to examine a potential causal relationship between repetitive monomorphic ventricular ectopy originating from the right ventricular outflow tract and cardiomyopathy and the role of ablation in reversing this process. Methods and Results—The study consisted of 27 patients (11 men; age, 47±15 years) with repetitive monomorphic ventricular ectopy, including 8 patients (30%) with depressed ventricular function (ejection fraction ≤45%). All patients underwent assessment of cardiac structure and function. The burden of ectopy was quantified through 24-hour Holter monitoring. Patients then underwent ablation guided by 3D mapping. After ablation, patients underwent repeated Holter monitoring and reassessment of cardiac function. Patients with depressed ventricular function were more likely to be older than patients with normal function (58±14 versus 42±18 years; P=0.013). However, the burden of ventricular ectopy was similar in patients with (17 859±13 488 ectopic beats per 24 hours) and without (17 541±11 479 ectopic beats per 24 hours; P=0.800) preserved ventricular function. Successful ablation was performed in 23 patients (85%), including 7 of 8 patients with depressed ventricular function. In this latter group, ventricular function improved in all patients (from 39±6% to 62±6%; P=0.017). Conclusions—Repetitive monomorphic ventricular ectopy (in the absence of sustained ventricular tachycardia) originating from the right ventricular outflow tract is an underappreciated cause of unexplained cardiomyopathy. Successful ablation of the focal source of ventricular ectopy results in normalization of left ventricular function. Patients with ectopy-induced cardiomyopathy are significantly older than patients with preserved ventricular function, which suggests either that older patients are more susceptible to the development of a cardiomyopathy or that the cardiomyopathy has had a longer period of time in which to evolve.

Primary Results From the SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial

Background— One variable that may influence cardiac resynchronization therapy response is the programmed atrioventricular (AV) delay. The SmartDelay Determined AV Optimization: A Comparison to Other AV Delay Methods Used in Cardiac Resynchronization Therapy (SMART-AV) Trial prospectively randomized patients to a fixed empirical AV delay (120 milliseconds), echocardiographically optimized AV delay, or AV delay optimized with SmartDelay, an electrogram-based algorithm. Methods and Results— A total of 1014 patients (68% men; mean age, 66±11 years; mean left ventricular ejection fraction, 25±7%) who met enrollment criteria received a cardiac resynchronization therapy defibrillator, and 980 patients were randomized in a 1:1:1 ratio. All patients were programmed (DDD-60 or DDDR-60) and evaluated after implantation and 3 and 6 months later. The primary end point was left ventricular end-systolic volume. Secondary end points included New York Heart Association class, quality-of-life score, 6-minute walk distance, left ventricular end-diastolic volume, and left ventricular ejection fraction. The medians (quartiles 1 and 3) for change in left ventricular end-systolic volume at 6 months for the SmartDelay, echocardiography, and fixed arms were −21 mL (−45 and 6 mL), −19 mL (−45 and 6 mL), and −15 mL (−41 and 6 mL), respectively. No difference in improvement in left ventricular end-systolic volume at 6 months was observed between the SmartDelay and echocardiography arms (P=0.52) or the SmartDelay and fixed arms (P=0.66). Secondary end points, including structural (left ventricular end-diastolic volume and left ventricular ejection fraction) and functional (6-minute walk, quality of life, and New York Heart Association classification) measures, were not significantly different between arms. Conclusions— Neither SmartDelay nor echocardiography was superior to a fixed AV delay of 120 milliseconds. The routine use of AV optimization techniques assessed in this trial is not warranted. However, these data do not exclude possible utility in selected patients who do not respond to cardiac resynchronization therapy. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00677014.

Long‐Term Outcome Following Successful Pulmonary Vein Isolation: Pattern and Prediction of Very Late Recurrence

Background: Despite encouraging results of pulmonary vein isolation (PVI) ablation for atrial fibrillation (AF), it is unclear whether there is genuine cure or there is an important attrition rate. We sought to determine the long‐term outcome of the initial responders who experienced a prolonged AF‐free complete response.

ISHNE/EHRA expert consensus on remote monitoring of cardiovascular implantable electronic devices (CIEDs)

We are in the midst of a rapidly evolving era of technology-assisted medicine. The field of telemedicine provides the opportunity for highly individualized medical management in a way that has never been possible before. Evolving medical technologies using cardiac implantable devices (CIEDs) with capabilities for remote monitoring permit evaluation of multiple parameters of cardiovascular physiology and risk, including cardiac rhythm, device function, blood pressure values, the presence of myocardial ischaemia, and the degree of compensation of congestive heart failure. Cardiac risk, device status, and response to therapies can now be assessed with these electronic systems of detection and reporting. This document reflects the extensive experience from investigators and innovators around the world who are shaping the evolution of this rapidly expanding field, focusing in particular on implantable pacemakers (IPGs), implantable cardioverter-defibrillators (ICDs), devices for cardiac resynchronization therapy (CRT) (both, with and without defibrillation properties), loop recorders, and haemodynamic monitoring devices. This document covers the basic methodologies, guidelines for their use, experience with existing applications, and the legal and reimbursement aspects associated with their use. To adequately cover this important emerging topic, the International Society for Holter and Noninvasive Electrocardiology (ISHNE) and the European Heart Rhythm Association (EHRA) combined their expertise in this field. We hope that the development of this field can contribute to improve care of our cardiovascular patients.

Right and left ventricular outflow tract tachycardias : Evidence for a common electrophysiologic mechanism

Introduction:“Idiopathic” ventricular arrhythmias most often arise from the right ventricular outflow tract (RVOT), although arrhythmias from the left ventricular outflow tract (LVOT) are also observed. While previous work has elucidated the mechanism and electropharmacologic profile of RVOT arrhythmias, it is unclear whether those from the LVOT share these properties. The purpose of this study was to characterize the electropharmacologic properties of RVOT and LVOT arrhythmias.

The utility of 12-lead Holter monitoring in patients with permanent atrial fibrillation for the identification of nonresponders after cardiac resynchronization therapy.

OBJECTIVES This study sought to determine the incidence of ineffective capture using 12-lead Holter monitoring and to assess whether this affects response to cardiac resynchronization therapy (CRT). BACKGROUND Cardiac resynchronization therapy is used in patients with atrial fibrillation (AF), prolonged QRS duration, and heart failure in the setting of ventricular dysfunction. The percentage of ventricular pacing is used as an indicator of adequate biventricular (BiV) pacing. Although device counters show a high pacing percentage, there may be ineffective capture because of underlying fusion and pseudo-fusion beats. METHODS We identified 19 patients (age 72 +/- 8 years, ejection fraction 18 +/- 5%), with permanent AF who underwent CRT. All patients received digoxin, beta-blockers, and amiodarone for rate control; device interrogation showed >90% BiV pacing. Patients had a 12-lead Holter monitor to assess the presence of effective (>90% fully paced beats/24 h) pacing. At 12 months post-CRT, the New York Heart Association functional class was reassessed and an echocardiogram was obtained and compared with pre-CRT. RESULTS Only 9 (47%) patients had effective pacing. The other 10 (53%) patients had 16.4 +/- 4.6% fusion and 23.5 +/- 8.7% pseudo-fusion beats. Long-term responders (> or =1 New York Heart Association functional class improvement) to CRT had a significantly higher percentage of fully paced beats (86.4 +/- 17.1% vs. 66.8 +/- 19.1%; p = 0.03) than nonresponders. CONCLUSIONS Pacing counters overestimate the degree of effective BiV pacing in patients with permanent AF undergoing CRT therapy. Only patients with complete capture responded clinically to CRT. These findings have important implications for the application of CRT to patients with permanent AF and heart failure.