Roy M. John

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

Ventricular arrhythmias and sudden cardiac death

Management strategies for ventricular arrhythmias are guided by the risk of sudden death and severity of symptoms. Patients with a substantial risk of sudden death usually need an implantable cardioverter defibrillator (ICD). Although ICDs effectively end most episodes of ventricular tachycardia or ventricular fibrillation and decrease mortality in specific populations of patients, they have inherent risks and limitations. Generally, antiarrhythmic drugs do not provide sufficient protection from sudden death, but do have a role in reducing arrhythmias that cause symptoms. Catheter ablation is likewise important for reducing the frequency of spontaneous arrhythmias and is curative for some patients, usually those with idiopathic arrhythmias and no heart disease. Arrhythmia surgery is now infrequent, offered by only a few specialised centres for refractory arrhythmias. Advances in understanding of genetic arrhythmia syndromes and in technology for mapping and ablation of ventricular arrhythmias, and enhanced algorithms in implantable devices for rhythm management, have contributed to improved outcomes.

Incidence and predictors of major complications from contemporary catheter ablation to treat cardiac arrhythmias

BACKGROUND Updated understanding of the risks of catheter ablation is important because techniques have evolved for procedures treating non-life-threatening as well as potentially lethal arrhythmias. OBJECTIVE This prospective study sought to assess the incidence and predictors of major complications from contemporary catheter ablation procedures at a high-volume center. METHODS Over a 2-year period, 1,676 consecutive ablation procedures were prospectively evaluated for major complications throughout 30 days postprocedure. Predictors of major complications were determined in a multivariate analysis adjusted for demographics, clinical variables, ablation type, and procedural factors. RESULTS Rates of major complications differed between procedure types, ranging from 0.8% for supraventricular tachycardia, 3.4% for idiopathic ventricular tachycardia (VT), 5.2% for atrial fibrillation (AF), and 6.0% for VT associated with structural heart disease (SHD). Ablation type (ablation for AF [odds ratio (OR) 5.53, 95% confidence interval (CI) 1.81 to 16.83], for VT with SHD [OR 8.61, 95% CI 2.37 to 31.31], or for idiopathic VT [OR 5.93, 95% CI 1.40 to 25.05] all referenced to supraventricular tachycardia ablation), and serum creatinine level >1.5 mg/dl (OR 2.48, 95% CI 1.07 to 5.76) were associated with increased adjusted risk of major complications, whereas age, gender, body mass index, international normalized ratio level, hypertension, coronary artery disease, diabetes, and prior cerebrovascular accident were not associated with increased risk. CONCLUSION In a large cohort of contemporary catheter ablation, major complication rates ranged between 0.8% and 6.0% depending on the ablation procedure performed. Aside from ablation type, renal insufficiency was the only independent predictor of a major complication.

Multicenter Experience With Extraction of the Sprint Fidelis Implantable Cardioverter-Defibrillator Lead

OBJECTIVES This study was undertaken to determine the safety and feasibility of extraction of the Sprint Fidelis (Medtronic, Minneapolis, Minnesota) lead. BACKGROUND The reported failure rate of the Sprint Fidelis defibrillator lead has increased to a range greater than initially appreciated with emerging evidence of an accelerating rate of fracture. At present, consensus guidelines continue to recommend against prophylactic extraction of the lead, citing major complication rates between 1.4% and 7.3%. However, data regarding the safety and feasibility of extraction of small-diameter, backfilled implantable cardioverter-defibrillator leads such as the Sprint Fidelis are limited. METHODS We performed a retrospective cohort study of consecutive patients undergoing extraction of Sprint Fidelis (models 6930, 6931, 6948, 6949) leads at 5 high-volume centers. Patient characteristics, indications for extraction, and use of countertraction sheath (CTS) assistance are reported. The risk of major and minor complications was determined. A multivariable logistic regression model was developed to predict factors associated with the use of CTS assistance. RESULTS Between May 2005 and August 2009, 349 Sprint Fidelis leads were extracted from 348 patients. All leads were removed completely. The average duration of the implanted lead was 27.5 months (range 0.03 to 58.8 months). Approximately one-half of the extracted leads were fractured (49.4%), and 26.5% were extracted prophylactically. The other major indication for extraction was infection (22.8%). Extraction was achieved with simple traction in 49.4% leads; CTS assistance was required in 174 cases (50.6%). In multivariable models, length of time since implantation was directly related to the need for CTS assistance (odds ratio per month since implantation: 1.035; 95% confidence interval: 1.010 to 1.061; p=0.006). There were no major procedural complications or deaths. CONCLUSIONS Extraction of the Sprint Fidelis lead can be performed safely by experienced operators at high-volume centers with a complication rate lower than that reported for older generation leads. However, leads with longer implant durations are associated with the use of CTS assistance. Recommendations regarding prophylactic Sprint Fidelis lead extraction may warrant reconsideration.

Endocardial pacemaker or defibrillator leads with infected vegetations: a single-center experience and consequences of transvenous extraction.

BACKGROUND Removal of infected endovascular leads if often required for cure of systemic infection, but the perceived risk of embolic events in the presence of large (>10 mm) vegetations has been considered a relative contraindication to transvenous removal. Surgical removal of pacemaker leads has been suggested in this situation to avoid occurrence of pulmonary embolization. METHODS Of 38 patients with infection of implanted pacemaker or cardioverter-defibrillator devices, those with evidence for systemic infection underwent transesophageal echocardiography to assess for the presence of vegetations. RESULTS Vegetations on endocardial leads or right-sided cardiac structures ranging in size from 10 mm to 38 mm in their largest dimension were detected in 9 patients. All patients underwent successful transvenous removal of endocardial leads. Five of 9 patients (55%) had evidence of pulmonary embolism. However, all 5 patients made a full recovery with antibiotic treatment and anticoagulation. Among patients with endocardial vegetations, there was no difference in hospitalization periods between those with or without pulmonary embolism (14.6 +/- 0.8 days vs 18.0 +/- 4.5 days, P =.7). CONCLUSIONS Transvenous removal of infected pacemaker leads is an alternative to open-thoracotomy removal of infected leads. Fifty-five percent of patients with vegetations on endocardial leads in our series experienced pulmonary embolism, but neither survival nor length of hospital stay were affected by this complication.

Catheter Ablation of Ventricular Tachycardia in Nonischemic Heart Disease

Background—Catheter ablation of ventricular tachycardia (VT) in nonischemic heart diseases can be challenging, and outcomes across different diseases are incompletely defined. The aim of this study was to describe the outcomes after catheter ablation for nonischemic VT in a large cohort and to compare the electrophysiological findings and outcomes according to the type of underlying disease. Methods and Results—Of the 891 consecutive patients undergoing catheter ablation for ventricular arrhythmias, 226 patients (52±14 years; 79% men) with sustained VT due to nonischemic heart disease were included. The primary end point was all-cause death or heart transplantation. Secondary end points were a composite of death, heart transplantation, or readmission because of VT recurrence within 1 year of discharge. Underlying heart diseases were dilated cardiomyopathy in 119 (53%), valvular heart disease in 34 (15%), arrhythmogenic right ventricular cardiomyopathy in 37 (16%), congenital heart disease in 16 (7%), cardiac sarcoidosis in 13 (6%), and hypertrophic cardiomyopathy in 7 (3%) patients. After ablation, inability to induce any VT was achieved in 55%, and another 20% had inducible VTs modified. Major complications occurred in 5%. Arrhythmogenic right ventricular cardiomyopathy had better outcomes than dilated cardiomyopathy for primary (P=0.002) and secondary end points (P=0.004). Sarcoidosis had worse outcome than dilated cardiomyopathy for secondary end point (P=0.002). At 1 year after the last ablation (a mean of 1.4±0.6 procedures, 1–4), freedom from death, heart transplantation, and readmission for VT recurrence were achieved in 173 (77%) patients. Conclusions—In patients with recurrent VT due to nonischemic heart disease, catheter ablation is often useful, although the outcome varies according to the nature of the underlying heart disease.

Transcoronary Ethanol Ablation for Recurrent Ventricular Tachycardia After Failed Catheter Ablation An Update

Background— Despite substantial progress, radiofrequency catheter ablation (RFCA) fails in some patients. After encouraging results with transcoronary ethanol ablation (TCEA), we began offering TCEA routinely when endocardial and epicardial RFCA failed or a deep intramural substrate was likely. Methods and Results— Among 274 consecutive patients who underwent 408 ventricular tachycardia (VT) ablation procedures, 27 patients (21 men; age, 63±13 years; left ventricular ejection fraction, 30±11%; ischemic cardiomyopathy, 14) had 29 TCEA procedures attempted. In 5 patients, TCEA was abandoned because of unfavorable anatomy. In 22 patients, a mean of 1.3±0.6 arteries (range, 1–3 arteries) were targeted for TCEA. After ablation, the targeted VT was no longer inducible in 18 of 22 (82%) patients. Complete heart block occurred in 5 patients, and 3 patients with advanced heart failure died within 30 days of the procedure. After the last TCEA procedure, a VT recurred in 64% of patients, and overall, 32% of patients died. Of 11 patients with prior VT storm, 9 were free of VT storm. At repeat study in 8 patients who had a recurrence, 7 had a new QRS morphology of VT originating from the same general substrate region as the prior VT. Conclusions— In patients with difficult-to-control VT in whom RFCA fails, TCEA prevents all VT recurrences in 36% and improves arrhythmia control in an additional 27%. Inadequate target vessels, collaterals, and recurrence of modified VTs limit efficacy, but TCEA continues to play an important role for difficult VTs in these high-risk patients.

Catheter Ablation of Ventricular Tachycardia in Non-ischemic Heart Disease

Background—Catheter ablation of ventricular tachycardia (VT) in nonischemic heart diseases can be challenging, and outcomes across different diseases are incompletely defined. The aim of this study was to describe the outcomes after catheter ablation for nonischemic VT in a large cohort and to compare the electrophysiological findings and outcomes according to the type of underlying disease. Methods and Results—Of the 891 consecutive patients undergoing catheter ablation for ventricular arrhythmias, 226 patients (52±14 years; 79% men) with sustained VT due to nonischemic heart disease were included. The primary end point was all-cause death or heart transplantation. Secondary end points were a composite of death, heart transplantation, or readmission because of VT recurrence within 1 year of discharge. Underlying heart diseases were dilated cardiomyopathy in 119 (53%), valvular heart disease in 34 (15%), arrhythmogenic right ventricular cardiomyopathy in 37 (16%), congenital heart disease in 16 (7%), cardiac sarcoidosis in 13 (6%), and hypertrophic cardiomyopathy in 7 (3%) patients. After ablation, inability to induce any VT was achieved in 55%, and another 20% had inducible VTs modified. Major complications occurred in 5%. Arrhythmogenic right ventricular cardiomyopathy had better outcomes than dilated cardiomyopathy for primary (P=0.002) and secondary end points (P=0.004). Sarcoidosis had worse outcome than dilated cardiomyopathy for secondary end point (P=0.002). At 1 year after the last ablation (a mean of 1.4±0.6 procedures, 1–4), freedom from death, heart transplantation, and readmission for VT recurrence were achieved in 173 (77%) patients. Conclusions—In patients with recurrent VT due to nonischemic heart disease, catheter ablation is often useful, although the outcome varies according to the nature of the underlying heart disease.

Ventricular Tachycardia in Cardiac Sarcoidosis: Characterization of Ventricular Substrate and Outcomes of Catheter Ablation

Background—Cardiac sarcoid–related ventricular tachycardia (VT) is a rare disorder; the underlying substrate and response to ablation are poorly understood. We sought to examine the ventricular substrate and outcomes of catheter ablation in this population. Methods and Results—Of 435 patients with nonischemic cardiomyopathy referred for VT ablation, 21 patients (5%) had cardiac sarcoidosis. Multiple inducible VTs were observed with mechanism consistent with scar-mediated re-entry in all VTs. Voltage maps showed widespread and confluent right ventricular scarring. Left ventricular scarring was patchy with a predilection for the basal septum, anterior wall, and perivalvular regions. Epicardial right ventricular scar overlay and exceeded the region of corresponding endocardial scar. After ≥1 procedures, ablation abolished ≥1 inducible VT in 90% and eliminated VT storm in 78% of patients; however, multiple residual VTs remained inducible. Failure to abolish all inducible VTs was because of septal intramural circuits or extensive right ventricular scarring. Multiple procedure VT-free survival was 37% at 1 year, but VT control was achievable in the majority of patients with fewer antiarrhythmic drugs compared with preablation (2.1±0.8 versus 1.1±0.8; P<0.001). Conclusions—Patients with cardiac sarcoidosis and VT exhibit ventricular substrate characterized by confluent right ventricular scarring and patchy left ventricular scarring capable of sustaining a large number of re-entrant circuits. Catheter ablation is effective in terminating VT storm and eliminating ≥1 inducible VT in the majority of patients, but recurrences are common. Ablation in conjunction with antiarrhythmic drugs can help palliate VT in this high-risk population.

Circadian Variation in Defibrillation Energy Requirements

BACKGROUND Reports have demonstrated a circadian variation in the incidence of acute myocardial infarction, ventricular arrhythmias, and sudden cardiac death. We tested the hypothesis that a similar circadian variation exists for defibrillation energy requirements in humans. METHODS AND RESULTS We reviewed the time of defibrillation threshold (DFT) measurements in 134 patients with implantable cardioverter-defibrillators (ICDs) who underwent 345 DFT measurements. The DFT was determined in 130 patients at implantation, in 121 at a 2 months, and in 94 at 6 months. All patients had nonthoracotomy systems. The morning DFT (8 AM to 12 noon) was 15.1 +/- 1.2 J compared with 13.1 +/- 0.9 J in the midafternoon (12 noon to 4 PM) and 13.0 +/- 0.7 J in the late afternoon (4 to 8 PM), P < .02. In a separate group of 930 patients implanted with an ICD system with date and time stamps for each therapy, we reviewed 1238 episodes of ventricular tachyarrhythmias treated with shock therapy. To corroborate the hypothesis that energy requirements for arrhythmia termination vary during the course of the day, we plotted the failed first shock frequency for all episodes per hour. There was a significant peak in failed first shocks in the morning compared with other time intervals (P = .02). CONCLUSIONS There is a morning peak in DFT and a corresponding morning peak in failed first shock frequency. This morning peak resembles the peaks seen in other cardiac events, specifically sudden cardiac death. These findings have important implications for appropriate ICD function, particularly in patients with marginal DFTs.