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Mortality and safety of catheter ablation for antiarrhythmic drug-refractory ventricular tachycardia in elderly patients with coronary artery disease
Mortality and safety of catheter ablation for antiarrhythmic drug-refractory ventricular tachycardia in elderly patients with coronary artery disease Keiichi Inada, MD, Kurt C. Roberts-Thomson, MBBS, PhD, Jens Seiler, MD, PhD, Daniel Steven, MD, Usha B. Tedrow, MD, Bruce A. Koplan, MD, William G. Stevenson, MD, FHRS From the Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts. BACKGROUND As the population ages, recurrent ventricular tachycardia (VT) is increasingly encountered in elderly patients with ischemic heart disease. Radiofrequency catheter ablation is useful for reducing VT therapy in patients with an implantable defibrillator. The utility of radiofrequency catheter ablation in the elderly is not well defined. OBJECTIVE The purpose of this study was to evaluate the prognosis and safety of radiofrequency catheter ablation of postinfarct VT in elderly patients. METHODS Radiofrequency catheter ablation was performed in 285 consecutive patients with recurrent postinfarct VT refractory to antiarrhythmic drugs. Mortality and outcomes were compared for an elderly group (age ⱖ75 years, n ⫽ 72) and a younger group (age ⬍75 years, n ⫽ 213). RESULTS The groups were similar with regard to baseline characteristics, except for a greater number of females in the elderly group (20.8% vs 10.8%, P ⫽ .03). Inducible VTs were abolished or modified in 79.2% of the elderly group and 87.8% of the younger group (P ⫽ .12). Major complications occurred in 5.6% of elderly
Introduction Sustained ventricular tachycardia (VT) is an important cause of morbidity and mortality in patients with ischemic heart disease. Although implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden death,1,2 shocks are Dr. Roberts-Thomson is the recipient of a Postgraduate Research Scholarship from the National Health and Medical Research Council of Australia (NHMRC grant ID 489417) and the Astra-Zeneca Fellowship in Medical Research from the Royal Australian College of Physicians. Dr. Seiler has received a research grant from St. Jude Medical (Switzerland). Dr. Steven has received a research grant from Biosense Webster. Dr. Tedrow has received research grants from Biosense Webster and Boston Scientific, and speaking honoraria from Boston Scientific, Medtronic, and St. Jude Medical. Dr. Koplan is a consultant for Boston Scientific and St. Jude Medical and has received speaking honoraria from Boston Scientific, Medtronic, and St. Jude Medical. Address reprint requests and correspondence: Dr. Keiichi Inada, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, 75 Francis Street, Boston, Massachusetts 02115. E-mail address: [email protected]. (Received December 23, 2009; accepted February 10, 2010.)
patients and 2.3% of younger patients (P ⫽ .48). Periprocedural mortality was similar between both groups (2/72 in elderly and 9/213 in younger group, P ⫽ .74). During mean follow-up of 42 ⫾ 33 months, 50.0% of the elderly group and 35.2% of the younger group died (P ⫽ .08). No VT was observed in 63.9% of the elderly patients and 60.1% of the younger patients, respectively (mean follow-up 18 ⫾ 24 months, P ⫽ .80). CONCLUSION Outcomes of catheter ablation are similar for selected elderly and younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival. KEYWORDS Catheter ablation; Elderly; Coronary artery disease; Mortality; Radiofrequency catheter ablation; Safety; Ventricular tachycardia ABBREVIATIONS ICD ⫽ implantable cardioverter-defibrillator; LV ⫽ left ventricle; VT ⫽ ventricular tachycardia (Heart Rhythm 2010;7:740 –744) © 2010 Heart Rhythm Society. All rights reserved.
associated with reduced quality of life,3 and episodes of VT are associated with reduced survival.4 VT ablation is an effective therapy for reducing recurrent arrhythmias.5,6 However, due to the complex underlying substrate, poor left ventricular function, and associated comorbidities, the success rates of ablation are lower for VT than for other arrhythmias, and a higher rate of complications is anticipated.7,8 The efficacy and risk of invasive procedures are generally less favorable in elderly compared with younger patients. Complication rates for supraventricular arrhythmias and atrial fibrillation have been reported to be similar in older and younger patients, although the risk of ablation of an accessory pathway may be increased in the elderly.9 –13 Furthermore, mortality due to ischemic heart disease is greater in the elderly regardless of arrhythmia.14 These considerations favor avoidance of invasive procedures in the elderly, but the mortality, safety, and efficacy of catheter ablation of VT in elderly patients with coronary artery disease have not been well defined.
1547-5271/$ -see front matter © 2010 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2010.02.019
Inada et al
VT Ablation in Elderly Patients with Ischemic Heart Disease
Methods Study subjects Data from a total of 289 consecutive patients with coronary artery disease and a prior myocardial infarction referred for VT ablation between January 1999 and September 2008 were reviewed. Patients who underwent only ethanol or cryothermal ablation (n ⫽ 4) were excluded. The study consisted of 285 consecutive VT patients who were divided into two groups according to age ⱖ75 years (elderly group) and ⬍75 years (younger group).
Electrophysiologic study Each patient gave written informed consent. Studies and data review were performed according to protocols approved by the Human Research Committee of Brigham and Women’s Hospital. Ventricular mapping and ablation were performed with saline irrigated or nonirrigated tip catheters as previously described.15–17 The mapping catheter was advanced into the left ventricle (LV) by either a retrograde aortic or a transseptal approach. Intravenous heparin boluses were administered to maintain the activated clotting time ⬎250 seconds. Conscious sedation was achieved with fentanyl and midazolam. Electroanatomic mapping was performed with the CARTO system (Biosense Webster, Diamond Bar, CA, USA). Bipolar electrograms were bandpass filtered from 30 to 500 Hz and digitally recorded along with a 12-lead surface ECG CardioLab EP system (General Electric Healthcare, Buckinghamshire, UK). VT was induced with up to three extrastimuli from the right ventricular apex. Ablation was guided by substrate mapping with or without entrainment mapping depending on VT stability.16 A total of 22 patients with failed endocardial ablation underwent percutaneous epicardial mapping and ablation as described by Sosa et al.18,19 Irrigated radiofrequency ablation was performed generally starting at 30 W and titrated to a maximum of 50 W. For nonirrigated ablation, energy was titrated to achieve a temperature of 60°C or a maximum power of 50 W.20 Applications were repeated in an area until pacing at 10 mA at 2-ms stimulus strength failed to capture. VT inducibility was assessed using programmed stimulation with up to three extrastimuli after 600-ms and 400-ms basic drive and burst pacing from the right ventricle. Sustained VT was defined as VT having a duration ⱖ30 seconds. Acute success was defined as the inability to induce any sustained VT or modification of inducible VTs with abolition of one or more clinical or presumptive clinical VTs.6 Procedural failure was defined as persistently inducible clinical or presumptive clinical VT. VT inducibility was not assessed after ablation if we believed that VT could adversely affect hemodynamic stability. After the procedure, patients were treated with heparin for the initial 24 to 48 hours, followed by either aspirin or warfarin.
Follow-up After ablation, all patients were observed with continuous ECG monitoring until hospital discharge. After discharge, all patients had follow-up either at an outpatient clinic or with their referring cardiologist. Recurrent VT was evaluated based
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on ECG recordings, 24-hour ambulatory monitoring, and/or ICD interrogation. In addition, the Social Security Death Index database queried between June 2 and June 6, 2009, was used to evaluate mortality. Periprocedural mortality was defined as death within 10 days of the procedure. Major complications were defined as those that resulted in permanent adverse effect, required surgical intervention, or required or delayed hospitalization.21 For patients with multiple procedures, the last procedure was included in the analysis, and follow-up was assessed from that procedure.
Statistical analysis Values are expressed as mean ⫾ SD. Comparison between groups was performed using Student’s t-test (unpaired). Proportions were compared using Chi-square analysis. Differences with P ⬍.05 were considered significant. Survival curves were created and compared using the Kaplan-Meier method.
Results Patient characteristics Clinical characteristics, except for age and gender, were similar between the elderly and younger groups (Table 1). The elderly group had more females than did the younger group (20.8% vs 10.8%, P ⫽ .03). All patients had failed antiarrhythmic therapy. Amiodarone was used in 59 (82%) of the elderly patients and 154 (72%) of the younger patients. Sotalol was used in 6 (8%) of the elderly patients and 32 (15%) of the younger patients.
Acute ablation outcome Procedural characteristics and outcome are listed in Table 2. The number of inducible sustained monomorphic VTs (range 1– 8) was not different between the two groups (2.7 ⫾ 1.5 in the elderly group and 2.4 ⫾ 1.5 in the younger group, P ⫽ .20). Elderly patients tended to have slower VTs (Table 2). Ablation was guided based only on substrate mapping during sinus or paced rhythm in 14 (19.4%) elderly patients and 68 (31.9%) younger patients, whereas both substrate and Table 1 groups
Clinical characteristics of the elderly and younger
Mean age (years) Gender (male/female) ICD prior to procedure Time since last MI (months) Ejection fraction (%) Coronary artery bypass graft MI site Anterior Inferior Anterior ⫹ inferior Prior ablation procedure No. of procedures
Elderly group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
78.9 ⫾ 3.5 57/15 66 (91.7%) 142.1 ⫾ 114.3 28.5 ⫾ 10.4 38 (52.8%)
62.1 ⫾ 8.9 190/23 188 (88.3%) 127.2 ⫾ 106.0 28.7 ⫾ 13.0 111 (52.1%)
20 47 3 32
51 (23.9%) 136 (63.8%) 19 (8.9%) 97/116 (45.5%) 1.7 ⫾ 1.1
(27.8%) (65.3%) (4.2%) (44.4%) 1.6 ⫾ 0.7
Values are given as number (%) or mean ⫾ SD. ICD ⫽ implantable cardioverter-defibrillator; MI ⫽ myocardial infarction.
P value ⬍.0001 .03 .62 .43 .94 .95 .39
.87 .22
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Heart Rhythm, Vol 7, No 6, June 2010
Table 2 Procedural characteristics and acute outcome of the elderly and younger groups
No. of VTs Mapping method Substrate VT Substrate ⫹ VT VT cycle length (ms) ⬎400 300–400 ⬍300 Transseptal approach Epicardial approach Acute procedural outcome Success Failure No assessment
Elder group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
2.7 ⫾ 1.5
2.4 ⫾ 1.5
14 (19.4%) 20 (27.8%) 34 (47.2%) 45 43 15 18 3
(62.5 %) (59.7 %) (20.8%) (25.0%) (4.2%)
57 (79.2%) 11 (15.3%) 2 (2.8%)
P value .20 .17*
68 (31.9%) 55 (25.8%) 86 (40.4%) 108 133 56 24 24
(50.7%) (62.4%) (26.3%) (11.3%) (11.3%)
.08 .68 .35 .004 .10 .12*
187 (87.8%) 16 (7.5%) 9 (4.2%)
Values are given as number (%) or mean ⫾ SD. VT ⫽ ventricular tachycardia. *Calculated by multi-way Chi-square analysis.
VT mappings were performed in 34 (47.2%) of elderly patients and 86 (40.4%) of younger patients (P ⫽ 0.17). These differences likely reflect the more frequent slower VTs in the elderly group. A transseptal approach was used for LV mapping in 18 (25.0%) patients in the elderly group and 24 (11.3%) patients in the younger group (P ⫽ .004), likely reflecting more peripheral vascular disease in the elderly. After ablation, no VT was inducible in 37 (51.4%) patients in the elderly group and 122 (57.3%) patients in the younger group. Inducible VTs were modified in 20 (27.8%) patients in the elderly group and 65 (30.5%) patients in the younger group. Ablation failed to modify VT in 11 (15.3%) patients in the elderly group and 16 (7.5%) patients in the younger group. Inducible VTs were not assessed after ablation in 2 elderly patients and 9 younger patients. These procedure outcomes were similar for the younger and elderly groups (P ⫽ .12).
Periprocedural mortality and complications Periprocedural mortality (within 10 days after the procedure) occurred in 2 (2.8%) elderly patients and 9 (4.2%) younger patients. Mortality was due to uncontrollable arrhythmias after ablation failed in 2 elderly patients and 4 younger patients. Other sources of morality were severe heart failure, septic shock, fatal pulmonary embolism, pneumonia, and uncontrollable bleeding during surgery for aortic aneurysm unrelated to the ablation procedure. Major nonfatal complications occurred in 4 (5.6%) elderly patients (Table 3): cardiac tamponade treated with percutaneous pericardiocentesis in 2, cerebral infarction in 1, and heart failure in 1. In the younger group, major nonfatal complications occurred in 5 (2.3%) patients; cardiogenic shock due to recurrent VT in association with severe ventricular dysfunction requiring mechanical support occurred in 1 patient. AV block occurred following right bundle or septal ablation in 3 patients. Rates of severe complication were not different between the two groups (P ⫽ .81).
Major complications including periprocedural mortality occurred in 3 (6.7%) females compared with 20 (8.8%) males (P ⫽ 1).
Total mortality Over mean follow-up of 45 ⫾ 33 months, 36 (50.0%) patients in the elderly group died. Two-year mortality was 29.2% in elderly patients and 23.0% in younger patients. In the elderly group, 14 (38.9%) of the patients who died were known to have experienced VT recurrences (despite abolition or modification of inducible VT at the time of ablation in 9 of these patients). In the younger group, 75 (35.2%) patients died, 39 (52.0%) of whom had documented episodes of recurrent VT (despite acute abolition or modification of inducible VT in 32 patients at the time of ablation). Elderly patients tended to reach the endpoint of death earlier than did younger patients, but the difference did not reach statistical significance (P ⫽ .08; Figure 1). Total mortality was 50.9% in male patients and 46.7% in female patients in the elderly group (P ⫽ 0.34) versus 34.2% in males and 30.4% in females in the younger group (P ⫽ .79).
VT recurrence Due to the referral nature of the population, the duration of follow-up for assessing recurrent VT was shorter than that for mortality (mean follow-up 20 ⫾ 24 months for elderly patients and 18 ⫾ 24 months for younger patients). At least one episode of sustained VT requiring termination by ICD or another intervention occurred in 36.1% of elderly patients and 39.9% of younger patients. Arrhythmia-free survival curves according to age are shown in Kaplan-Meier format in Figure 2. There was no significant difference between the two groups (P ⫽ .80). The 1-year VT recurrent rate was 33.3% in male patients and 20.0% in female patients in the elderly group (P ⫽ .16) versus 35.8% in male patients and 30.4% in female patients in the younger group (P ⫽ .45).
Discussion This study demonstrates that although elderly patients tended to have higher long-term mortality, survival at 1 year was reasonable and periprocedural mortality was similar to that of the younger group. The complication rate was Table 3
Complications of the elderly and younger groups
All complications Major complications Periprocedural mortality Cardiogenic shock Cardiac tamponade Cerebral infarction Heart failure Complete AV block Minor complications Groin hematoma Local vascular complication
Elderly group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
7 (9.7%) 6 (8.3%) 2 0 2 1 1 0 1 (1.3%) 0 1
17 (8.0%) 14 (6.6%) 9 1 0 1 0 3 3 (1.4%) 2 1
P value .83 .81
.99
Inada et al
VT Ablation in Elderly Patients with Ischemic Heart Disease
Figure 1 Kaplan-Meier curve of survival after radiofrequency catheter ablation of ventricular tachycardia. The elderly group had shorter survival, although this difference did not reach statistical significance (P ⫽ .08).
greater, although not statistically different, in elderly patients compared with younger patients. Furthermore, the acute and long-term VT recurrence rates after catheter ablation for elderly patients with ischemic VT were similar to the rates for younger patients. Approximately 6% of the US population has coronary artery disease, with the prevalence reaching 20% in subjects older than 75 years.22,23 ICD therapy in older patients has been shown to have mortality risk reduction comparable to that of younger patients.24 However, other investigators have shown that, due to the increase in noncardiac death, the mortality risk of elderly people receiving an ICD is increased threefold compared with younger people.14 As the number of elderly patients with ischemic heart disease continues to increase, more elderly patients with ICDs and VT can be expected. Episodes of VT are markers for mortality in patients who have an ICD (MADIT II,25 SCD-HeFT26), and shocks elicited by VT decrease quality of life.6 Antiarrhythmic drug therapy can reduce VT episodes, but failure and side effects are common.27,28 Catheter ablation is an important option for reducing VT episodes.6 Because the elderly are generally recognized to be at increased risk for cardiac procedures and often have more limited expectation for survival, the use of invasive therapies, such as ablation, should be considered carefully in this patient population. It has been assumed that the elderly are at higher risk for complications from invasive procedures. However, in patients undergoing catheter ablation of arrhythmias, the relationship between risk and outcomes is inconsistent. Zado et al9 found no difference in complication rates between different age groups undergoing ablation, but only a small number of elderly patients with VT were included in the study. Kihel et al10 found similar complication rates between patients older and younger than 75 years with AV nodal reentrant tachycardia. In contrast, other studies that did not include VT patients reported that elderly patients undergoing ablation of left-sided accessory pathways had a
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higher incidence of complications.11,12 Chen et al12 reported that 4 (14%) of 29 elderly patients had complications (3 with retrograde LV approach and 1 with transseptal approach), including cardiac tamponade, acute aortic regurgitation, aortic dissection, and stroke. These findings suggest that elderly patients may be at increased risk when access to the left-sided cardiac chambers is required via a transseptal or retrograde LV approach. Risk may be increased by age-associated structural changes, more frequent arteriosclerosis, and increased stiffness of arterial and cardiac chambers.29 –31 Few reports have described the results and complications of catheter ablation of ischemic VT in elderly patients. Zado et al9 examined the acute outcome of catheter ablation for supraventricular tachycardia and VT in patients of various ages. However, their study included only three elderly patients with VT, and no information was provided regarding the underlying substrate and the long-term outcome. Several studies involving more than 100 patients have reported the long-term outcome of ablation of ischemic VT, but specific delineation of outcomes in the elderly was not reported.7,32 Calkins et al7 reported the ablation outcome of 146 patients with mean age of 65 years. The recurrence rate was 46% during mean follow-up period of 243 days, with mortality of 18%. Similar results were observed by Della Bella et al,32 who reported that 49% of patients with mean age of 67 years had VT recurrence during median follow-up of 36 months. A multicenter trial of 231 patients that included some of the patients in our study group found a recurrence rate of 51%.33 Median age was 68 years, and age was not a predictor of outcome in multivariable analysis.
Study limitations Our study has several limitations and caveats. It is important to consider the potential impact of referral bias on patient selection. Our patients were referred due to difficult to control monomorphic VT despite antiarrhythmic drug therapy. This group generally had advanced disease, as is consistent with the
Figure 2 Kaplan-Meier curve of freedom from ventricular tachycardia. There was no significant difference in arrhythmia-free survival probabilities between the two groups (P ⫽ .80).
744 observed mortality and with other studies of catheter ablation. Physicians may be more likely to refer patients who are relatively healthy and whose procedural risk is perceived to be acceptable. Hence, despite their older age, ventricular function, a marker of disease severity, of the elderly patients was similar to that of the younger patients. There was a trend toward having slower and hemodynamically tolerable VT in the elderly group, and substrate-guided ablation was less frequently the sole mapping approach. These findings are consistent with a referral bias. We do not know how many patients were not referred due to severe comorbidities and the anticipation of poor survival regardless of arrhythmia control. Similar biases likely are operative in other studies that reported similar acute procedural outcomes for older and younger patients undergoing ablation for supraventricular tachycardia and atrial fibrillation.10 –13 A second limitation is that our study results apply only to the population with coronary artery disease. A third limitation is that, due to the referral nature of our population, follow-up for VT recurrences was shorter than the available mortality follow-up through the Social Security Death Index, and a recent ICD interrogation was available for only 70% of patients. A fourth limitation is that the statistical power to detect differences between elderly and younger patients was limited by the relatively small number of elderly patients.
Conclusion The risks and outcomes in selected elderly patients with recurrent VT who are referred for catheter ablation are similar to that in younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival.
References 1. Bigger JT Jr. Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery. coronary artery bypass graft (CABG) patch trial investigators. N Engl J Med 1997;337:1569 –1575. 2. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sudden death in patients with coronary artery disease. multicenter unsustained tachycardia trial investigators. N Engl J Med 1999;341:1882–1890. 3. Schron EB, Exner DV, Yao Q, et al. Quality of life in the antiarrhythmics versus implantable defibrillators trial: impact of therapy and influence of adverse symptoms and defibrillator shocks. Circulation 2002;105:589 –594. 4. Moss AJ, Greenberg H, Case RB, et al. Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator. Circulation 2004;110:3760 –3765. 5. Reddy VY, Reynolds MR, Neuzil P, et al. Prophylactic catheter ablation for the prevention of defibrillator therapy. N Engl J Med 2007;357:2657–2665. 6. Aliot EM, Stevenson WG, Almendral-Garrote JM, et al. EHRA/HRS expert consensus on catheter ablation of ventricular arrhythmias: developed in a partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC), and the Heart Rhythm Society (HRS); in collaboration with the American College of Cardiology (ACC) and the American Heart Association (AHA). Europace 2009;11:771– 817. 7. Calkins H, Epstein A, Packer D, et al. Catheter ablation of ventricular tachycardia in patients with structural heart disease using cooled radiofrequency energy: results of a prospective multicenter study. cooled RF multi center investigators group. J Am Coll Cardiol 2000;35:1905–1914. 8. Segal OR, Chow AW, Markides V, Schilling RJ, Peters NS, Davies DW. Long-term results after ablation of infarct-related ventricular tachycardia. Heart Rhythm 2005;2:474 – 482. 9. Zado ES, Callans DJ, Gottlieb CD, et al. Efficacy and safety of catheter ablation in octogenarians. J Am Coll Cardiol 2000;35:458 – 462.
Heart Rhythm, Vol 7, No 6, June 2010 10. Kihel J, Da Costa A, Kihel A, et al. Long-term efficacy and safety of radiofrequency ablation in elderly patients with atrioventricular nodal re-entrant tachycardia. Europace 2006;8:416 – 420. 11. Epstein LM, Chiesa N, Wong MN, et al. Radiofrequency catheter ablation in the treatment of supraventricular tachycardia in the elderly. J Am Coll Cardiol 1994;23:1356 –1362. 12. Chen SA, Chiang CE, Yang CJ, et al. Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: clinical features, electrophysiologic characteristics and results of radiofrequency ablation. J Am Coll Cardiol 1994;23:702–708. 13. Zado E, Callans DJ, Riley M, et al. Long-term clinical efficacy and risk of catheter ablation for atrial fibrillation in the elderly. J Cardiovasc Electrophysiol 2008;19:621– 626. 14. Panotopoulos PT, Axtell K, Anderson AJ, et al. Efficacy of the implantable cardioverter-defibrillator in the elderly. J Am Coll Cardiol 1997;29:556 –560. 15. Stevenson WG, Friedman PL, Kocovic D, Sager PT, Saxon LA, Pavri B. Radiofrequency catheter ablation of ventricular tachycardia after myocardial infarction. Circulation 1998;98:308 –314. 16. Soejima K, Suzuki M, Maisel WH, et al. Catheter ablation in patients with multiple and unstable ventricular tachycardias after myocardial infarction: short ablation lines guided by reentry circuit isthmuses and sinus rhythm mapping. Circulation 2001;104:664 – 669. 17. Brunckhorst CB, Delacretaz E, Soejima K, Maisel WH, Friedman PL, Stevenson WG. Identification of the ventricular tachycardia isthmus after infarction by pace mapping. Circulation 2004;110:652– 659. 18. Sosa E, Scanavacca M, d’Avila A, Oliveira F, Ramires JA. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction. J Am Coll Cardiol 2000;35:1442–1449. 19. Zei PC, Stevenson WG. Epicardial catheter mapping and ablation of ventricular tachycardia. Heart Rhythm 2006;3:360 –363. 20. Soejima K, Delacretaz E, Suzuki M, et al. Saline-cooled versus standard radiofrequency catheter ablation for infarct-related ventricular tachycardias. Circulation 2001;103:1858 –1862. 21. Calkins H, Yong P, Miller JM, et al. Catheter ablation of accessory pathways, atrioventricular nodal reentrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. The Atakr multicenter investigators group. Circulation 1999;99:262–270. 22. Lloyd-Jones D, Adams R, Carnethon M, et al. Heart disease and stroke statistics—2009 update: a report from the American Heart Association statistics committee and stroke statistics subcommittee. Circulation 2009;119:e21– e181. 23. Rich MW. Epidemiology, clinical features, and prognosis of acute myocardial infarction in the elderly. Am J Geriatr Cardiol 2006;15:7,11. 24. Chan PS, Nallamothu BK, Spertus JA, et al. Impact of age and medical comorbidity on the effectiveness of implantable cardioverter-defibrillators for primary prevention. Circ Cardiovasc Qual Outcomes 2009;2:16 –24. 25. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002;346:877– 883. 26. Poole, JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patients with heart failure. N Engl J Med 2008;359:1009 –1017. 27. Cardiac arrest in Seattle: conventional versus amiodarone drug evaluation (the CASCADE study). Am J Cardiol 1991;67:578 –584. 28. Connolly SJ, Dorian P, Roberts RS, et al. Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial. JAMA 2006;295:165–171. 29. Kitzman DW, Scholz DG, Hagen PT, Ilstrup DM, Edwards WD. Age-related changes in normal human hearts during the first 10 decades of life. part II (maturity): a quantitative anatomic study of 765 specimens from subjects 20 to 99 years old. Mayo Clin Proc 1988;63:137–146. 30. Lakatta EG, Levy D. Arterial and cardiac aging: major shareholders in cardiovascular disease enterprises: part II: the aging heart in health: links to heart disease. Circulation 2003;107:346 –354. 31. Lakatta EG, Levy D. Arterial and cardiac aging: major shareholders in cardiovascular disease enterprises: part I: aging arteries: a “set up” for vascular disease. Circulation 2003;107:139 –146. 32. Della Bella P, Riva S, Fassini G, et al. Incidence and significance of pleomorphism in patients with postmyocardial infarction ventricular tachycardia. acute and long-term outcome of radiofrequency catheter ablation. Eur Heart J 2004; 25:1127–1138. 33. Stevenson WG, Wilber DJ, Natale A, Jackman WM, et al. Irrigated radiofrequency catheter ablation guided by electroanatomic mapping for recurrent ventricular tachycardia after myocardial infarction: the multicenter Thermocool ventricular tachycardia ablation trial. Circulation 2008;118:2773–2782.
Introduction Sustained ventricular tachycardia (VT) is an important cause of morbidity and mortality in patients with ischemic heart disease. Although implantable cardioverter-defibrillators (ICDs) reduce the risk of sudden death,1,2 shocks are Dr. Roberts-Thomson is the recipient of a Postgraduate Research Scholarship from the National Health and Medical Research Council of Australia (NHMRC grant ID 489417) and the Astra-Zeneca Fellowship in Medical Research from the Royal Australian College of Physicians. Dr. Seiler has received a research grant from St. Jude Medical (Switzerland). Dr. Steven has received a research grant from Biosense Webster. Dr. Tedrow has received research grants from Biosense Webster and Boston Scientific, and speaking honoraria from Boston Scientific, Medtronic, and St. Jude Medical. Dr. Koplan is a consultant for Boston Scientific and St. Jude Medical and has received speaking honoraria from Boston Scientific, Medtronic, and St. Jude Medical. Address reprint requests and correspondence: Dr. Keiichi Inada, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, 75 Francis Street, Boston, Massachusetts 02115. E-mail address: [email protected]. (Received December 23, 2009; accepted February 10, 2010.)
patients and 2.3% of younger patients (P ⫽ .48). Periprocedural mortality was similar between both groups (2/72 in elderly and 9/213 in younger group, P ⫽ .74). During mean follow-up of 42 ⫾ 33 months, 50.0% of the elderly group and 35.2% of the younger group died (P ⫽ .08). No VT was observed in 63.9% of the elderly patients and 60.1% of the younger patients, respectively (mean follow-up 18 ⫾ 24 months, P ⫽ .80). CONCLUSION Outcomes of catheter ablation are similar for selected elderly and younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival. KEYWORDS Catheter ablation; Elderly; Coronary artery disease; Mortality; Radiofrequency catheter ablation; Safety; Ventricular tachycardia ABBREVIATIONS ICD ⫽ implantable cardioverter-defibrillator; LV ⫽ left ventricle; VT ⫽ ventricular tachycardia (Heart Rhythm 2010;7:740 –744) © 2010 Heart Rhythm Society. All rights reserved.
associated with reduced quality of life,3 and episodes of VT are associated with reduced survival.4 VT ablation is an effective therapy for reducing recurrent arrhythmias.5,6 However, due to the complex underlying substrate, poor left ventricular function, and associated comorbidities, the success rates of ablation are lower for VT than for other arrhythmias, and a higher rate of complications is anticipated.7,8 The efficacy and risk of invasive procedures are generally less favorable in elderly compared with younger patients. Complication rates for supraventricular arrhythmias and atrial fibrillation have been reported to be similar in older and younger patients, although the risk of ablation of an accessory pathway may be increased in the elderly.9 –13 Furthermore, mortality due to ischemic heart disease is greater in the elderly regardless of arrhythmia.14 These considerations favor avoidance of invasive procedures in the elderly, but the mortality, safety, and efficacy of catheter ablation of VT in elderly patients with coronary artery disease have not been well defined.
1547-5271/$ -see front matter © 2010 Heart Rhythm Society. All rights reserved.
doi:10.1016/j.hrthm.2010.02.019
Inada et al
VT Ablation in Elderly Patients with Ischemic Heart Disease
Methods Study subjects Data from a total of 289 consecutive patients with coronary artery disease and a prior myocardial infarction referred for VT ablation between January 1999 and September 2008 were reviewed. Patients who underwent only ethanol or cryothermal ablation (n ⫽ 4) were excluded. The study consisted of 285 consecutive VT patients who were divided into two groups according to age ⱖ75 years (elderly group) and ⬍75 years (younger group).
Electrophysiologic study Each patient gave written informed consent. Studies and data review were performed according to protocols approved by the Human Research Committee of Brigham and Women’s Hospital. Ventricular mapping and ablation were performed with saline irrigated or nonirrigated tip catheters as previously described.15–17 The mapping catheter was advanced into the left ventricle (LV) by either a retrograde aortic or a transseptal approach. Intravenous heparin boluses were administered to maintain the activated clotting time ⬎250 seconds. Conscious sedation was achieved with fentanyl and midazolam. Electroanatomic mapping was performed with the CARTO system (Biosense Webster, Diamond Bar, CA, USA). Bipolar electrograms were bandpass filtered from 30 to 500 Hz and digitally recorded along with a 12-lead surface ECG CardioLab EP system (General Electric Healthcare, Buckinghamshire, UK). VT was induced with up to three extrastimuli from the right ventricular apex. Ablation was guided by substrate mapping with or without entrainment mapping depending on VT stability.16 A total of 22 patients with failed endocardial ablation underwent percutaneous epicardial mapping and ablation as described by Sosa et al.18,19 Irrigated radiofrequency ablation was performed generally starting at 30 W and titrated to a maximum of 50 W. For nonirrigated ablation, energy was titrated to achieve a temperature of 60°C or a maximum power of 50 W.20 Applications were repeated in an area until pacing at 10 mA at 2-ms stimulus strength failed to capture. VT inducibility was assessed using programmed stimulation with up to three extrastimuli after 600-ms and 400-ms basic drive and burst pacing from the right ventricle. Sustained VT was defined as VT having a duration ⱖ30 seconds. Acute success was defined as the inability to induce any sustained VT or modification of inducible VTs with abolition of one or more clinical or presumptive clinical VTs.6 Procedural failure was defined as persistently inducible clinical or presumptive clinical VT. VT inducibility was not assessed after ablation if we believed that VT could adversely affect hemodynamic stability. After the procedure, patients were treated with heparin for the initial 24 to 48 hours, followed by either aspirin or warfarin.
Follow-up After ablation, all patients were observed with continuous ECG monitoring until hospital discharge. After discharge, all patients had follow-up either at an outpatient clinic or with their referring cardiologist. Recurrent VT was evaluated based
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on ECG recordings, 24-hour ambulatory monitoring, and/or ICD interrogation. In addition, the Social Security Death Index database queried between June 2 and June 6, 2009, was used to evaluate mortality. Periprocedural mortality was defined as death within 10 days of the procedure. Major complications were defined as those that resulted in permanent adverse effect, required surgical intervention, or required or delayed hospitalization.21 For patients with multiple procedures, the last procedure was included in the analysis, and follow-up was assessed from that procedure.
Statistical analysis Values are expressed as mean ⫾ SD. Comparison between groups was performed using Student’s t-test (unpaired). Proportions were compared using Chi-square analysis. Differences with P ⬍.05 were considered significant. Survival curves were created and compared using the Kaplan-Meier method.
Results Patient characteristics Clinical characteristics, except for age and gender, were similar between the elderly and younger groups (Table 1). The elderly group had more females than did the younger group (20.8% vs 10.8%, P ⫽ .03). All patients had failed antiarrhythmic therapy. Amiodarone was used in 59 (82%) of the elderly patients and 154 (72%) of the younger patients. Sotalol was used in 6 (8%) of the elderly patients and 32 (15%) of the younger patients.
Acute ablation outcome Procedural characteristics and outcome are listed in Table 2. The number of inducible sustained monomorphic VTs (range 1– 8) was not different between the two groups (2.7 ⫾ 1.5 in the elderly group and 2.4 ⫾ 1.5 in the younger group, P ⫽ .20). Elderly patients tended to have slower VTs (Table 2). Ablation was guided based only on substrate mapping during sinus or paced rhythm in 14 (19.4%) elderly patients and 68 (31.9%) younger patients, whereas both substrate and Table 1 groups
Clinical characteristics of the elderly and younger
Mean age (years) Gender (male/female) ICD prior to procedure Time since last MI (months) Ejection fraction (%) Coronary artery bypass graft MI site Anterior Inferior Anterior ⫹ inferior Prior ablation procedure No. of procedures
Elderly group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
78.9 ⫾ 3.5 57/15 66 (91.7%) 142.1 ⫾ 114.3 28.5 ⫾ 10.4 38 (52.8%)
62.1 ⫾ 8.9 190/23 188 (88.3%) 127.2 ⫾ 106.0 28.7 ⫾ 13.0 111 (52.1%)
20 47 3 32
51 (23.9%) 136 (63.8%) 19 (8.9%) 97/116 (45.5%) 1.7 ⫾ 1.1
(27.8%) (65.3%) (4.2%) (44.4%) 1.6 ⫾ 0.7
Values are given as number (%) or mean ⫾ SD. ICD ⫽ implantable cardioverter-defibrillator; MI ⫽ myocardial infarction.
P value ⬍.0001 .03 .62 .43 .94 .95 .39
.87 .22
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Table 2 Procedural characteristics and acute outcome of the elderly and younger groups
No. of VTs Mapping method Substrate VT Substrate ⫹ VT VT cycle length (ms) ⬎400 300–400 ⬍300 Transseptal approach Epicardial approach Acute procedural outcome Success Failure No assessment
Elder group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
2.7 ⫾ 1.5
2.4 ⫾ 1.5
14 (19.4%) 20 (27.8%) 34 (47.2%) 45 43 15 18 3
(62.5 %) (59.7 %) (20.8%) (25.0%) (4.2%)
57 (79.2%) 11 (15.3%) 2 (2.8%)
P value .20 .17*
68 (31.9%) 55 (25.8%) 86 (40.4%) 108 133 56 24 24
(50.7%) (62.4%) (26.3%) (11.3%) (11.3%)
.08 .68 .35 .004 .10 .12*
187 (87.8%) 16 (7.5%) 9 (4.2%)
Values are given as number (%) or mean ⫾ SD. VT ⫽ ventricular tachycardia. *Calculated by multi-way Chi-square analysis.
VT mappings were performed in 34 (47.2%) of elderly patients and 86 (40.4%) of younger patients (P ⫽ 0.17). These differences likely reflect the more frequent slower VTs in the elderly group. A transseptal approach was used for LV mapping in 18 (25.0%) patients in the elderly group and 24 (11.3%) patients in the younger group (P ⫽ .004), likely reflecting more peripheral vascular disease in the elderly. After ablation, no VT was inducible in 37 (51.4%) patients in the elderly group and 122 (57.3%) patients in the younger group. Inducible VTs were modified in 20 (27.8%) patients in the elderly group and 65 (30.5%) patients in the younger group. Ablation failed to modify VT in 11 (15.3%) patients in the elderly group and 16 (7.5%) patients in the younger group. Inducible VTs were not assessed after ablation in 2 elderly patients and 9 younger patients. These procedure outcomes were similar for the younger and elderly groups (P ⫽ .12).
Periprocedural mortality and complications Periprocedural mortality (within 10 days after the procedure) occurred in 2 (2.8%) elderly patients and 9 (4.2%) younger patients. Mortality was due to uncontrollable arrhythmias after ablation failed in 2 elderly patients and 4 younger patients. Other sources of morality were severe heart failure, septic shock, fatal pulmonary embolism, pneumonia, and uncontrollable bleeding during surgery for aortic aneurysm unrelated to the ablation procedure. Major nonfatal complications occurred in 4 (5.6%) elderly patients (Table 3): cardiac tamponade treated with percutaneous pericardiocentesis in 2, cerebral infarction in 1, and heart failure in 1. In the younger group, major nonfatal complications occurred in 5 (2.3%) patients; cardiogenic shock due to recurrent VT in association with severe ventricular dysfunction requiring mechanical support occurred in 1 patient. AV block occurred following right bundle or septal ablation in 3 patients. Rates of severe complication were not different between the two groups (P ⫽ .81).
Major complications including periprocedural mortality occurred in 3 (6.7%) females compared with 20 (8.8%) males (P ⫽ 1).
Total mortality Over mean follow-up of 45 ⫾ 33 months, 36 (50.0%) patients in the elderly group died. Two-year mortality was 29.2% in elderly patients and 23.0% in younger patients. In the elderly group, 14 (38.9%) of the patients who died were known to have experienced VT recurrences (despite abolition or modification of inducible VT at the time of ablation in 9 of these patients). In the younger group, 75 (35.2%) patients died, 39 (52.0%) of whom had documented episodes of recurrent VT (despite acute abolition or modification of inducible VT in 32 patients at the time of ablation). Elderly patients tended to reach the endpoint of death earlier than did younger patients, but the difference did not reach statistical significance (P ⫽ .08; Figure 1). Total mortality was 50.9% in male patients and 46.7% in female patients in the elderly group (P ⫽ 0.34) versus 34.2% in males and 30.4% in females in the younger group (P ⫽ .79).
VT recurrence Due to the referral nature of the population, the duration of follow-up for assessing recurrent VT was shorter than that for mortality (mean follow-up 20 ⫾ 24 months for elderly patients and 18 ⫾ 24 months for younger patients). At least one episode of sustained VT requiring termination by ICD or another intervention occurred in 36.1% of elderly patients and 39.9% of younger patients. Arrhythmia-free survival curves according to age are shown in Kaplan-Meier format in Figure 2. There was no significant difference between the two groups (P ⫽ .80). The 1-year VT recurrent rate was 33.3% in male patients and 20.0% in female patients in the elderly group (P ⫽ .16) versus 35.8% in male patients and 30.4% in female patients in the younger group (P ⫽ .45).
Discussion This study demonstrates that although elderly patients tended to have higher long-term mortality, survival at 1 year was reasonable and periprocedural mortality was similar to that of the younger group. The complication rate was Table 3
Complications of the elderly and younger groups
All complications Major complications Periprocedural mortality Cardiogenic shock Cardiac tamponade Cerebral infarction Heart failure Complete AV block Minor complications Groin hematoma Local vascular complication
Elderly group ⱖ75 years (n ⫽ 72)
Younger group ⬍75 years (n ⫽ 213)
7 (9.7%) 6 (8.3%) 2 0 2 1 1 0 1 (1.3%) 0 1
17 (8.0%) 14 (6.6%) 9 1 0 1 0 3 3 (1.4%) 2 1
P value .83 .81
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Inada et al
VT Ablation in Elderly Patients with Ischemic Heart Disease
Figure 1 Kaplan-Meier curve of survival after radiofrequency catheter ablation of ventricular tachycardia. The elderly group had shorter survival, although this difference did not reach statistical significance (P ⫽ .08).
greater, although not statistically different, in elderly patients compared with younger patients. Furthermore, the acute and long-term VT recurrence rates after catheter ablation for elderly patients with ischemic VT were similar to the rates for younger patients. Approximately 6% of the US population has coronary artery disease, with the prevalence reaching 20% in subjects older than 75 years.22,23 ICD therapy in older patients has been shown to have mortality risk reduction comparable to that of younger patients.24 However, other investigators have shown that, due to the increase in noncardiac death, the mortality risk of elderly people receiving an ICD is increased threefold compared with younger people.14 As the number of elderly patients with ischemic heart disease continues to increase, more elderly patients with ICDs and VT can be expected. Episodes of VT are markers for mortality in patients who have an ICD (MADIT II,25 SCD-HeFT26), and shocks elicited by VT decrease quality of life.6 Antiarrhythmic drug therapy can reduce VT episodes, but failure and side effects are common.27,28 Catheter ablation is an important option for reducing VT episodes.6 Because the elderly are generally recognized to be at increased risk for cardiac procedures and often have more limited expectation for survival, the use of invasive therapies, such as ablation, should be considered carefully in this patient population. It has been assumed that the elderly are at higher risk for complications from invasive procedures. However, in patients undergoing catheter ablation of arrhythmias, the relationship between risk and outcomes is inconsistent. Zado et al9 found no difference in complication rates between different age groups undergoing ablation, but only a small number of elderly patients with VT were included in the study. Kihel et al10 found similar complication rates between patients older and younger than 75 years with AV nodal reentrant tachycardia. In contrast, other studies that did not include VT patients reported that elderly patients undergoing ablation of left-sided accessory pathways had a
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higher incidence of complications.11,12 Chen et al12 reported that 4 (14%) of 29 elderly patients had complications (3 with retrograde LV approach and 1 with transseptal approach), including cardiac tamponade, acute aortic regurgitation, aortic dissection, and stroke. These findings suggest that elderly patients may be at increased risk when access to the left-sided cardiac chambers is required via a transseptal or retrograde LV approach. Risk may be increased by age-associated structural changes, more frequent arteriosclerosis, and increased stiffness of arterial and cardiac chambers.29 –31 Few reports have described the results and complications of catheter ablation of ischemic VT in elderly patients. Zado et al9 examined the acute outcome of catheter ablation for supraventricular tachycardia and VT in patients of various ages. However, their study included only three elderly patients with VT, and no information was provided regarding the underlying substrate and the long-term outcome. Several studies involving more than 100 patients have reported the long-term outcome of ablation of ischemic VT, but specific delineation of outcomes in the elderly was not reported.7,32 Calkins et al7 reported the ablation outcome of 146 patients with mean age of 65 years. The recurrence rate was 46% during mean follow-up period of 243 days, with mortality of 18%. Similar results were observed by Della Bella et al,32 who reported that 49% of patients with mean age of 67 years had VT recurrence during median follow-up of 36 months. A multicenter trial of 231 patients that included some of the patients in our study group found a recurrence rate of 51%.33 Median age was 68 years, and age was not a predictor of outcome in multivariable analysis.
Study limitations Our study has several limitations and caveats. It is important to consider the potential impact of referral bias on patient selection. Our patients were referred due to difficult to control monomorphic VT despite antiarrhythmic drug therapy. This group generally had advanced disease, as is consistent with the
Figure 2 Kaplan-Meier curve of freedom from ventricular tachycardia. There was no significant difference in arrhythmia-free survival probabilities between the two groups (P ⫽ .80).
744 observed mortality and with other studies of catheter ablation. Physicians may be more likely to refer patients who are relatively healthy and whose procedural risk is perceived to be acceptable. Hence, despite their older age, ventricular function, a marker of disease severity, of the elderly patients was similar to that of the younger patients. There was a trend toward having slower and hemodynamically tolerable VT in the elderly group, and substrate-guided ablation was less frequently the sole mapping approach. These findings are consistent with a referral bias. We do not know how many patients were not referred due to severe comorbidities and the anticipation of poor survival regardless of arrhythmia control. Similar biases likely are operative in other studies that reported similar acute procedural outcomes for older and younger patients undergoing ablation for supraventricular tachycardia and atrial fibrillation.10 –13 A second limitation is that our study results apply only to the population with coronary artery disease. A third limitation is that, due to the referral nature of our population, follow-up for VT recurrences was shorter than the available mortality follow-up through the Social Security Death Index, and a recent ICD interrogation was available for only 70% of patients. A fourth limitation is that the statistical power to detect differences between elderly and younger patients was limited by the relatively small number of elderly patients.
Conclusion The risks and outcomes in selected elderly patients with recurrent VT who are referred for catheter ablation are similar to that in younger patients. Advanced age should not preclude ablation when recurrent VT is adversely affecting quality of life in elderly patients who otherwise have a reasonable expectation for survival.
References 1. Bigger JT Jr. Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after coronary-artery bypass graft surgery. coronary artery bypass graft (CABG) patch trial investigators. N Engl J Med 1997;337:1569 –1575. 2. Buxton AE, Lee KL, Fisher JD, Josephson ME, Prystowsky EN, Hafley G. A randomized study of the prevention of sudden death in patients with coronary artery disease. multicenter unsustained tachycardia trial investigators. N Engl J Med 1999;341:1882–1890. 3. Schron EB, Exner DV, Yao Q, et al. Quality of life in the antiarrhythmics versus implantable defibrillators trial: impact of therapy and influence of adverse symptoms and defibrillator shocks. Circulation 2002;105:589 –594. 4. Moss AJ, Greenberg H, Case RB, et al. Long-term clinical course of patients after termination of ventricular tachyarrhythmia by an implanted defibrillator. Circulation 2004;110:3760 –3765. 5. Reddy VY, Reynolds MR, Neuzil P, et al. Prophylactic catheter ablation for the prevention of defibrillator therapy. N Engl J Med 2007;357:2657–2665. 6. Aliot EM, Stevenson WG, Almendral-Garrote JM, et al. EHRA/HRS expert consensus on catheter ablation of ventricular arrhythmias: developed in a partnership with the European Heart Rhythm Association (EHRA), a registered branch of the European Society of Cardiology (ESC), and the Heart Rhythm Society (HRS); in collaboration with the American College of Cardiology (ACC) and the American Heart Association (AHA). Europace 2009;11:771– 817. 7. Calkins H, Epstein A, Packer D, et al. Catheter ablation of ventricular tachycardia in patients with structural heart disease using cooled radiofrequency energy: results of a prospective multicenter study. cooled RF multi center investigators group. J Am Coll Cardiol 2000;35:1905–1914. 8. Segal OR, Chow AW, Markides V, Schilling RJ, Peters NS, Davies DW. Long-term results after ablation of infarct-related ventricular tachycardia. Heart Rhythm 2005;2:474 – 482. 9. Zado ES, Callans DJ, Gottlieb CD, et al. Efficacy and safety of catheter ablation in octogenarians. J Am Coll Cardiol 2000;35:458 – 462.
Heart Rhythm, Vol 7, No 6, June 2010 10. Kihel J, Da Costa A, Kihel A, et al. Long-term efficacy and safety of radiofrequency ablation in elderly patients with atrioventricular nodal re-entrant tachycardia. Europace 2006;8:416 – 420. 11. Epstein LM, Chiesa N, Wong MN, et al. Radiofrequency catheter ablation in the treatment of supraventricular tachycardia in the elderly. J Am Coll Cardiol 1994;23:1356 –1362. 12. Chen SA, Chiang CE, Yang CJ, et al. Accessory pathway and atrioventricular node reentrant tachycardia in elderly patients: clinical features, electrophysiologic characteristics and results of radiofrequency ablation. J Am Coll Cardiol 1994;23:702–708. 13. Zado E, Callans DJ, Riley M, et al. Long-term clinical efficacy and risk of catheter ablation for atrial fibrillation in the elderly. J Cardiovasc Electrophysiol 2008;19:621– 626. 14. Panotopoulos PT, Axtell K, Anderson AJ, et al. Efficacy of the implantable cardioverter-defibrillator in the elderly. J Am Coll Cardiol 1997;29:556 –560. 15. Stevenson WG, Friedman PL, Kocovic D, Sager PT, Saxon LA, Pavri B. Radiofrequency catheter ablation of ventricular tachycardia after myocardial infarction. Circulation 1998;98:308 –314. 16. Soejima K, Suzuki M, Maisel WH, et al. Catheter ablation in patients with multiple and unstable ventricular tachycardias after myocardial infarction: short ablation lines guided by reentry circuit isthmuses and sinus rhythm mapping. Circulation 2001;104:664 – 669. 17. Brunckhorst CB, Delacretaz E, Soejima K, Maisel WH, Friedman PL, Stevenson WG. Identification of the ventricular tachycardia isthmus after infarction by pace mapping. Circulation 2004;110:652– 659. 18. Sosa E, Scanavacca M, d’Avila A, Oliveira F, Ramires JA. Nonsurgical transthoracic epicardial catheter ablation to treat recurrent ventricular tachycardia occurring late after myocardial infarction. J Am Coll Cardiol 2000;35:1442–1449. 19. Zei PC, Stevenson WG. Epicardial catheter mapping and ablation of ventricular tachycardia. Heart Rhythm 2006;3:360 –363. 20. Soejima K, Delacretaz E, Suzuki M, et al. Saline-cooled versus standard radiofrequency catheter ablation for infarct-related ventricular tachycardias. Circulation 2001;103:1858 –1862. 21. Calkins H, Yong P, Miller JM, et al. Catheter ablation of accessory pathways, atrioventricular nodal reentrant tachycardia, and the atrioventricular junction: final results of a prospective, multicenter clinical trial. The Atakr multicenter investigators group. Circulation 1999;99:262–270. 22. Lloyd-Jones D, Adams R, Carnethon M, et al. Heart disease and stroke statistics—2009 update: a report from the American Heart Association statistics committee and stroke statistics subcommittee. Circulation 2009;119:e21– e181. 23. Rich MW. Epidemiology, clinical features, and prognosis of acute myocardial infarction in the elderly. Am J Geriatr Cardiol 2006;15:7,11. 24. Chan PS, Nallamothu BK, Spertus JA, et al. Impact of age and medical comorbidity on the effectiveness of implantable cardioverter-defibrillators for primary prevention. Circ Cardiovasc Qual Outcomes 2009;2:16 –24. 25. Moss AJ, Zareba W, Hall WJ, et al. Prophylactic implantation of a defibrillator in patients with myocardial infarction and reduced ejection fraction. N Engl J Med 2002;346:877– 883. 26. Poole, JE, Johnson GW, Hellkamp AS, et al. Prognostic importance of defibrillator shocks in patients with heart failure. N Engl J Med 2008;359:1009 –1017. 27. Cardiac arrest in Seattle: conventional versus amiodarone drug evaluation (the CASCADE study). Am J Cardiol 1991;67:578 –584. 28. Connolly SJ, Dorian P, Roberts RS, et al. Comparison of beta-blockers, amiodarone plus beta-blockers, or sotalol for prevention of shocks from implantable cardioverter defibrillators: the OPTIC study: a randomized trial. JAMA 2006;295:165–171. 29. Kitzman DW, Scholz DG, Hagen PT, Ilstrup DM, Edwards WD. Age-related changes in normal human hearts during the first 10 decades of life. part II (maturity): a quantitative anatomic study of 765 specimens from subjects 20 to 99 years old. Mayo Clin Proc 1988;63:137–146. 30. Lakatta EG, Levy D. Arterial and cardiac aging: major shareholders in cardiovascular disease enterprises: part II: the aging heart in health: links to heart disease. Circulation 2003;107:346 –354. 31. Lakatta EG, Levy D. Arterial and cardiac aging: major shareholders in cardiovascular disease enterprises: part I: aging arteries: a “set up” for vascular disease. Circulation 2003;107:139 –146. 32. Della Bella P, Riva S, Fassini G, et al. Incidence and significance of pleomorphism in patients with postmyocardial infarction ventricular tachycardia. acute and long-term outcome of radiofrequency catheter ablation. Eur Heart J 2004; 25:1127–1138. 33. Stevenson WG, Wilber DJ, Natale A, Jackman WM, et al. Irrigated radiofrequency catheter ablation guided by electroanatomic mapping for recurrent ventricular tachycardia after myocardial infarction: the multicenter Thermocool ventricular tachycardia ablation trial. Circulation 2008;118:2773–2782.