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One-year outcome after radiofrequency catheter ablation of symptomatic ventricular arrhythmia from right ventricular outflow tract
Efficacy and Temporal Stability of Reduced Safety Margins for Ventricular Defibrillation. Primary Results From the Low-Energy Safety Study (LESS)
$48,700 for the ICD group, compared to $17,000 for the non-ICD group. The cost-effectiveness of the ICD was $78,400 per year of life gained during 8 years of follow-up. Conclusions: The ICD provides a survival advantage to patients with VT/VF and has a cost-effectiveness that falls in an acceptable range. Perspective: This population-based retrospective study provides reassuring confirmation that the ICD prolongs survival in unselected Medicare patients with life-threatening VT/VF, not only in highly selected patients who have been the subjects of prospective randomized trials. FM
Gold MR, Higgins S, Klein R, et al. Circulation 2002;105:2043– 8. Study Question: Are relatively small safety margins for defibrillation effective in patients with an implantable cardioverter-defibrillator (ICD)? Methods: A dual-coil defibrillation lead and active can pectoral pulse generator were implanted in 638 patients. Defibrillation threshold (DFT) testing was performed at the time of implant and 3 and 12 months later. The DFT was the lowest energy that terminated ventricular fibrillation (VF), and the DFT⫹⫹ was the lowest energy that terminated VF in three consecutive attempts. In 392 patients, defibrillation efficacy for induced VF was tested in random fashion at various energy levels. In 636 patients, the efficacy of a range of programmed energies for spontaneous arrhythmia episodes was tested in random fashion. The mean duration of follow-up was 2 years. Results: The mean DFT was 7.9 J, and the mean DFT⫹⫹ was 9.1 J. A safety margin of 4 – 6 J was associated with a conversion success rate of 98% for induced VF, which did not differ significantly from the 99.1–99.8% success rates of higher energy shocks. The conversion success rate with a 4 – 6 J safety margin was stable over time. During follow-up, the efficacy of a 4 – 6 J safety margin for spontaneous arrhythmias was 97.3%, identical to the efficacy of maximal energies. Conclusions: In patients with a contemporary biphasic, active-can ICD, a defibrillation safety margin of approximately 5 J above the DFT⫹⫹ is safe and effective. Perspective: Initial ICD shocks that have a relatively low energy but that are effective have the advantage of prolonging battery life and reducing the charge time, thereby decreasing the probability of syncope prior to delivery of a shock. However, because of the rigorous testing needed to arrive at a safety margin of 4 – 6 J, the results of this study may not have much impact on clinical practice. FM
Sudden Death in Patients With Implantable Cardioverter Defibrillators. The Importance of PostShock Electromechanical Dissociation Mitchell LB, Pineda EA, Titus JL, Bartosch PM, Benditt DG. J Am Coll Cardiol 2002;39:1323– 8. Study Question: What are the mechanisms of sudden death in patients with an implantable cardioverter/defibrillator (ICD)? Methods: Data for this study were compiled from reviews of patient deaths during pre-clinical studies of the transvenous ICD between the years of 1994 and 1999. Based on review of medical records, descriptions by family members, clinical summaries provided by the treating physicians, death certificates and stored ICD events, deaths were classified as sudden, cardiac-nonsudden or noncardiac. Results: Among 4889 patients who participated in ICD trials, there were 320 deaths. The mean age of the patients who died was 68 years, their mean ejection fraction was 0.27, and 86% had coronary artery disease. Forty-nine percent of deaths were cardiac-nonsudden, 28% were sudden, 22% were noncardiac and 1% could not be classified. The most common cause of cardiac nonsudden death was heart failure (83%). A probable mechanism of death could be determined in 76% of the sudden deaths. The most common mechanism of sudden death were: post-shock electromechanical dissociation (EMD, 29%), failure of the ICD to terminate ventricular tachycardia/fibrillation (VT/ VF, 26%), primary EMD (16%) and incessant VT/VF (13%). Post-shock EMD was associated with a lower ejection fraction and NYHA class III/IV. Conclusions: Approximately 30% of deaths in patients with an ICD are sudden, and the most common mechanism of sudden death is post-shock EMD. Perspective: These data suggest a need for screening of patients with severe heart disease who are likely to die from EMD despite appropriate ICD therapy for VT/VF. It remains to be determined whether maneuvers such as biventricular pacing may decrease the risk of EMD in class III/IV patients. FM
One-Year Outcome After Radiofrequency Catheter Ablation of Symptomatic Ventricular Arrhythmia From Right Ventricular Outflow Tract Krittayaphong R, Sriratanasathavorn C, Bhuripanyo K, et al. Am J Cardiol 2002;89:1269 –74. Study Question: What is the impact of radiofrequency catheter ablation of frequent ventricular premature complexes (PVCs) arising in the right ventricular outflow tract (RVOT) on quality-of-life (QOL)? Methods: The subjects of the study were 34 symptomatic patients with ⬎100 PVCs/hour on a 24-hour Holter monitor recording. The PVCs all had a left bundle branch block morphology and an inferior axis. QOL was assessed with
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the SF-36 questionnaire before catheter ablation. Holter monitoring and QOL assessment were repeated 1 and 12 months after catheter ablation. Results: The mean age of the patients was 42 years. The baseline mean number of PVCs in 24 hours was 23,987, and 82% of patients had couplets, 48% had triplets and 21% had short runs of nonsustained ventricular tachycardia. The acute success rate of radiofrequency catheter ablation was 97%. The only complication was a groin hematoma in one patient. Eight patients underwent a second ablation procedure because they were still symptomatic from frequent PVCs. The mean number of PVCs in 24 hours decreased to 2053 at 1 month of follow-up, and to 872 at 12 months. Symptoms and QOL were significantly improved at 1 and 12 months. Conclusions: Radiofrequency catheter ablation of symptomatic frequent PVCs arising in the RVOT is safe and effective and significantly improves QOL. Perspective: There is no mention in this study of the response to pharmacologic treatment, and the patients apparently were not drug refractory. Unless a subsequent study demonstrates that radiofrequency catheter ablation is more effective than pharmacologic therapy for symptomatic PVCs, it would seem prudent to limit radiofrequency catheter ablation to patients whose symptoms have not abated with drug therapy. FM
was shorter in Group 1 (146 minutes) than in Group 2 (179 minutes). Conclusions: Right atrial ablation is of no incremental value in patients undergoing intraoperative left atrial ablation for AF with radiofrequency energy during open-heart surgery. Perspective: Because the study was retrospective and nonrandomized, it does not provide definitive evidence that right atrial ablation is unnecessary in patients with AF. Another limitation of the study is that complete block across ablation lines was not confirmed, and therefore it is not known whether the relatively low success rate of the procedure was attributable to incomplete lines of block or to some other factor. FM
Electrogram Polarity Reversal as an Additional Indicator of Breakthroughs From the Left Atrium to the Pulmonary Veins Yamane T, Shah DC, Jais P, et al. J Am Coll Cardiol 2002;39: 1337– 44. Study Question: Does mapping of electrogram polarity reversal (EPR) facilitate segmental ostial ablation to isolate the pulmonary veins (PVs) in patients with atrial fibrillation (AF)? Methods: The subjects of the study were 157 patients with paroxysmal AF. Segmental ostial ablation of the PVs was guided by activation mapping of PV potentials in 113 patients (Group 1) and by activation and EPR mapping in 44 patients (Group 2). Ostial electrograms were recorded with a decapolar ring catheter. In EPR mapping, the ostial sites at which there was reversal of electrogram polarity were considered to be breakthroughs from the left atrium to the PVs. The duration of radiofrequency energy (RF) needed to isolate the PVs in Groups 1 and 2 was compared. Results: 99% of PVs were successfully isolated. The mean duration of RF needed to isolate the PVs in Groups 1 and 2 did not differ significantly. However, the duration of RF needed to isolate PVs that had broad PV fascicles was longer in Group 1 (12.3 minutes) than in Group 2 (10.3 minutes). Clinical outcomes were similar in the two groups. During follow-up, 41% of patients had recurrent AF. After additional ablation procedures, 74% of patients were free of AF without antiarrhythmic drug therapy at 9 months of followup. Conclusions: EPR mapping facilitates ablation of broad PV muscle fascicles. Perspective: Despite successful pulmonary vein isolation, AF recurred in 26% of patients. Although there has been major progress in catheter ablation of AF (with much of the progress being attributable to the group that performed this study), identification of the most effective ablation technique for AF that persists despite PV isolation remains a challenge. FM
Left Atrial vs. Bi-Atrial Maze Operation Using Intraoperatively Cooled-Tip Radiofrequency Ablation in Patients Undergoing Open-Heart Surgery. Safety and Efficacy Deneke T, Khargi K, Grewe PH, et al. J Am Coll Cardiol 2002;39: 1644 –50. Study Question: Is right atrial ablation necessary in patients undergoing intraoperative ablation in the left atrium (LA) for atrial fibrillation (AF)? Methods: This was a retrospective review of patients who underwent intraoperative radiofrequency ablation for AF either only in the LA (Group 1) or in both the left and right atria (Group 2). All patients had an indication for openheart surgery other than AF. LA ablation consisted of ablation lines encircling the pulmonary vein ostia and lines between the ostia, across the posterior LA and between the left inferior pulmonary vein and the mitral annulus. Patients were treated with sotalol or metoprolol for at least 6 months. Results: There were 21 patients in Group 1 and 49 in Group 2. The mean age of the patients was 66 years, their mean LA dimension was 50 mm and the mean duration of AF was 10 years. The duration of follow-up ranged from 1–50 months. Sinus rhythm was restored in 82% of Group 1 patients, compared to 75% in Group 2. The mean bypass duration
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$48,700 for the ICD group, compared to $17,000 for the non-ICD group. The cost-effectiveness of the ICD was $78,400 per year of life gained during 8 years of follow-up. Conclusions: The ICD provides a survival advantage to patients with VT/VF and has a cost-effectiveness that falls in an acceptable range. Perspective: This population-based retrospective study provides reassuring confirmation that the ICD prolongs survival in unselected Medicare patients with life-threatening VT/VF, not only in highly selected patients who have been the subjects of prospective randomized trials. FM
Gold MR, Higgins S, Klein R, et al. Circulation 2002;105:2043– 8. Study Question: Are relatively small safety margins for defibrillation effective in patients with an implantable cardioverter-defibrillator (ICD)? Methods: A dual-coil defibrillation lead and active can pectoral pulse generator were implanted in 638 patients. Defibrillation threshold (DFT) testing was performed at the time of implant and 3 and 12 months later. The DFT was the lowest energy that terminated ventricular fibrillation (VF), and the DFT⫹⫹ was the lowest energy that terminated VF in three consecutive attempts. In 392 patients, defibrillation efficacy for induced VF was tested in random fashion at various energy levels. In 636 patients, the efficacy of a range of programmed energies for spontaneous arrhythmia episodes was tested in random fashion. The mean duration of follow-up was 2 years. Results: The mean DFT was 7.9 J, and the mean DFT⫹⫹ was 9.1 J. A safety margin of 4 – 6 J was associated with a conversion success rate of 98% for induced VF, which did not differ significantly from the 99.1–99.8% success rates of higher energy shocks. The conversion success rate with a 4 – 6 J safety margin was stable over time. During follow-up, the efficacy of a 4 – 6 J safety margin for spontaneous arrhythmias was 97.3%, identical to the efficacy of maximal energies. Conclusions: In patients with a contemporary biphasic, active-can ICD, a defibrillation safety margin of approximately 5 J above the DFT⫹⫹ is safe and effective. Perspective: Initial ICD shocks that have a relatively low energy but that are effective have the advantage of prolonging battery life and reducing the charge time, thereby decreasing the probability of syncope prior to delivery of a shock. However, because of the rigorous testing needed to arrive at a safety margin of 4 – 6 J, the results of this study may not have much impact on clinical practice. FM
Sudden Death in Patients With Implantable Cardioverter Defibrillators. The Importance of PostShock Electromechanical Dissociation Mitchell LB, Pineda EA, Titus JL, Bartosch PM, Benditt DG. J Am Coll Cardiol 2002;39:1323– 8. Study Question: What are the mechanisms of sudden death in patients with an implantable cardioverter/defibrillator (ICD)? Methods: Data for this study were compiled from reviews of patient deaths during pre-clinical studies of the transvenous ICD between the years of 1994 and 1999. Based on review of medical records, descriptions by family members, clinical summaries provided by the treating physicians, death certificates and stored ICD events, deaths were classified as sudden, cardiac-nonsudden or noncardiac. Results: Among 4889 patients who participated in ICD trials, there were 320 deaths. The mean age of the patients who died was 68 years, their mean ejection fraction was 0.27, and 86% had coronary artery disease. Forty-nine percent of deaths were cardiac-nonsudden, 28% were sudden, 22% were noncardiac and 1% could not be classified. The most common cause of cardiac nonsudden death was heart failure (83%). A probable mechanism of death could be determined in 76% of the sudden deaths. The most common mechanism of sudden death were: post-shock electromechanical dissociation (EMD, 29%), failure of the ICD to terminate ventricular tachycardia/fibrillation (VT/ VF, 26%), primary EMD (16%) and incessant VT/VF (13%). Post-shock EMD was associated with a lower ejection fraction and NYHA class III/IV. Conclusions: Approximately 30% of deaths in patients with an ICD are sudden, and the most common mechanism of sudden death is post-shock EMD. Perspective: These data suggest a need for screening of patients with severe heart disease who are likely to die from EMD despite appropriate ICD therapy for VT/VF. It remains to be determined whether maneuvers such as biventricular pacing may decrease the risk of EMD in class III/IV patients. FM
One-Year Outcome After Radiofrequency Catheter Ablation of Symptomatic Ventricular Arrhythmia From Right Ventricular Outflow Tract Krittayaphong R, Sriratanasathavorn C, Bhuripanyo K, et al. Am J Cardiol 2002;89:1269 –74. Study Question: What is the impact of radiofrequency catheter ablation of frequent ventricular premature complexes (PVCs) arising in the right ventricular outflow tract (RVOT) on quality-of-life (QOL)? Methods: The subjects of the study were 34 symptomatic patients with ⬎100 PVCs/hour on a 24-hour Holter monitor recording. The PVCs all had a left bundle branch block morphology and an inferior axis. QOL was assessed with
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the SF-36 questionnaire before catheter ablation. Holter monitoring and QOL assessment were repeated 1 and 12 months after catheter ablation. Results: The mean age of the patients was 42 years. The baseline mean number of PVCs in 24 hours was 23,987, and 82% of patients had couplets, 48% had triplets and 21% had short runs of nonsustained ventricular tachycardia. The acute success rate of radiofrequency catheter ablation was 97%. The only complication was a groin hematoma in one patient. Eight patients underwent a second ablation procedure because they were still symptomatic from frequent PVCs. The mean number of PVCs in 24 hours decreased to 2053 at 1 month of follow-up, and to 872 at 12 months. Symptoms and QOL were significantly improved at 1 and 12 months. Conclusions: Radiofrequency catheter ablation of symptomatic frequent PVCs arising in the RVOT is safe and effective and significantly improves QOL. Perspective: There is no mention in this study of the response to pharmacologic treatment, and the patients apparently were not drug refractory. Unless a subsequent study demonstrates that radiofrequency catheter ablation is more effective than pharmacologic therapy for symptomatic PVCs, it would seem prudent to limit radiofrequency catheter ablation to patients whose symptoms have not abated with drug therapy. FM
was shorter in Group 1 (146 minutes) than in Group 2 (179 minutes). Conclusions: Right atrial ablation is of no incremental value in patients undergoing intraoperative left atrial ablation for AF with radiofrequency energy during open-heart surgery. Perspective: Because the study was retrospective and nonrandomized, it does not provide definitive evidence that right atrial ablation is unnecessary in patients with AF. Another limitation of the study is that complete block across ablation lines was not confirmed, and therefore it is not known whether the relatively low success rate of the procedure was attributable to incomplete lines of block or to some other factor. FM
Electrogram Polarity Reversal as an Additional Indicator of Breakthroughs From the Left Atrium to the Pulmonary Veins Yamane T, Shah DC, Jais P, et al. J Am Coll Cardiol 2002;39: 1337– 44. Study Question: Does mapping of electrogram polarity reversal (EPR) facilitate segmental ostial ablation to isolate the pulmonary veins (PVs) in patients with atrial fibrillation (AF)? Methods: The subjects of the study were 157 patients with paroxysmal AF. Segmental ostial ablation of the PVs was guided by activation mapping of PV potentials in 113 patients (Group 1) and by activation and EPR mapping in 44 patients (Group 2). Ostial electrograms were recorded with a decapolar ring catheter. In EPR mapping, the ostial sites at which there was reversal of electrogram polarity were considered to be breakthroughs from the left atrium to the PVs. The duration of radiofrequency energy (RF) needed to isolate the PVs in Groups 1 and 2 was compared. Results: 99% of PVs were successfully isolated. The mean duration of RF needed to isolate the PVs in Groups 1 and 2 did not differ significantly. However, the duration of RF needed to isolate PVs that had broad PV fascicles was longer in Group 1 (12.3 minutes) than in Group 2 (10.3 minutes). Clinical outcomes were similar in the two groups. During follow-up, 41% of patients had recurrent AF. After additional ablation procedures, 74% of patients were free of AF without antiarrhythmic drug therapy at 9 months of followup. Conclusions: EPR mapping facilitates ablation of broad PV muscle fascicles. Perspective: Despite successful pulmonary vein isolation, AF recurred in 26% of patients. Although there has been major progress in catheter ablation of AF (with much of the progress being attributable to the group that performed this study), identification of the most effective ablation technique for AF that persists despite PV isolation remains a challenge. FM
Left Atrial vs. Bi-Atrial Maze Operation Using Intraoperatively Cooled-Tip Radiofrequency Ablation in Patients Undergoing Open-Heart Surgery. Safety and Efficacy Deneke T, Khargi K, Grewe PH, et al. J Am Coll Cardiol 2002;39: 1644 –50. Study Question: Is right atrial ablation necessary in patients undergoing intraoperative ablation in the left atrium (LA) for atrial fibrillation (AF)? Methods: This was a retrospective review of patients who underwent intraoperative radiofrequency ablation for AF either only in the LA (Group 1) or in both the left and right atria (Group 2). All patients had an indication for openheart surgery other than AF. LA ablation consisted of ablation lines encircling the pulmonary vein ostia and lines between the ostia, across the posterior LA and between the left inferior pulmonary vein and the mitral annulus. Patients were treated with sotalol or metoprolol for at least 6 months. Results: There were 21 patients in Group 1 and 49 in Group 2. The mean age of the patients was 66 years, their mean LA dimension was 50 mm and the mean duration of AF was 10 years. The duration of follow-up ranged from 1–50 months. Sinus rhythm was restored in 82% of Group 1 patients, compared to 75% in Group 2. The mean bypass duration
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