Temporal and geographical trends in indications for implantation of cardiac defibrillators in Europe 1993-1998. Medtronic ICD System Investigators

Despite the demonstrated efficacy of implantable cardioverter defibrillators (ICDs) in reducing sudden and total mortality in selected populations, their implantation rates vary greatly between countries. The aim of our study was to analyze temporal and geographical trends in ICD implantations in countries with similar health related expenditure in Western Europe. A total of 2,257 patients from ten European evaluation studies of Medtronic defibrillators and defibrillation electrodes, conducted between 1993 and 1998, representing 12 countries, was included in this analysis. Rates of implantation and clinical characteristics were compared between countries and years of implantation. Rates of implantation differed greatly between Western European countries and did not correlate with indices of health related expenditure (i.e., number of patients per physician and number of patients per hospital bed). However, there was a strong and statistically significant negative correlation between the use of amiodarone and the rates of implantation (r = -0.66, P = 0.02). Temporal trends showed a significant increase in the age of the patients receiving an ICD between 1993 and 1998 (57 +/- 14 vs 61 +/- 12 years, mean +/- SD, P < 0.001). There was also a temporal trend towards an increased incidence of coronary artery disease and a significant decrease in the incidence of cardiomyopathy. There was a temporal increase in implantations in patients with a history of ventricular tachycardia. Despite a general scientific agreement that ICDs are a first line treatment for patients at high risk of sudden cardiac death, their acceptance remains low in several developed countries. This low acceptance may not be entirely related to budget constraint but may also be related to their perceived efficacy by physicians and health authorities.     

Predictors of Appropriate Implantable Cardioverter Defibrillator (ICD) Therapy in Primary Prevention Patients with Ischemic and Nonischemic Cardiomyopathy

Background: We sought to assess predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients receiving primary prevention ICDs. Methods: Four hundred twenty‐one consecutive patients (ischemic and nonischemic) undergoing primary prevention ICD implantation were studied. Patients were grouped based on the presence/absence of appropriate ICD therapy. Summary data and stored electrograms from ICDs were reviewed to determine appropriateness of therapy. Predictors of therapy were assessed by both univariate and multivariate Cox regression analysis. Results: Of 421 primary prevention patients undergoing ICD implantation, 79 (19%) had received appropriate ICD therapies. By univariate comparison, nonsustained ventricular tachycardia (NSVT), male sex, left ventricle diastolic diameter (LVDD), and hypertension were all significant predictors for ICD therapy over a mean follow‐up time of 751 ± 493 days (P ≤ 0.05). The use ofβ‐blockers was found to be a negative predictor. In the ischemic cardiomyopathy (ICM) population, 55 (17%) patients received ICD therapy and this was predicted by NSVT, hypertension, LVDD, and left atrial diameter.β‐blockers were protective. In the nonischemic dilated cardiomyopathy (NIDCM) population, 24 (23%) received appropriate therapies, which were predicted by NSVT, male sex, dual chamber device, lack of biventricular device, and lack ofβ‐blockers. By multivariate analysis, NSVT, hypertension, and lack ofβ‐blockers were significant for ICM, while NSVT and absence ofβ‐blockers were predictive for NIDCM. Ejection fraction, New York Heart Association class, and QRS width were not significantly different between therapy and no‐therapy groups in any population. Conclusions: ICD‐delivered therapy occurred in 19% of primary prevention patients with both ischemic and dilated cardiomyopathy and was predicted by NSVT and a lack ofβ‐blocker use. (PACE 2010; 33:320–329)     

Implantation Trends and Patient Profiles for Pacemakers and Implantable Cardioverter Defibrillators in the United States: 1993–2006

Background: Prior studies of cardiac rhythm management devices (pacemakers [PM] and implantable cardioverter defibrillators [ICD]) utilization in the United States have been limited to the Medicare population. We evaluated the national trends for the implantation of PMs and ICDs including the burden of device replacement. Methods: The Nationwide Inpatient Sample was queried to identify PM and ICD patients between 1993 and 2006 using ICD‐9‐CM codes, including demographics, health profile, and economic data. The Charlson Comorbidity Index (CCI) and replacement burden were calculated, and changes over time studied. Results: From 1993 to 2006, 2.4 million patients received a primary PM and 0.8 million received an ICD, while there were 369,000 PM replacements and 74,000 ICD replacements. Women comprised 49% of PM and 24% of ICD patients. The mean ICD replacement burden was 8.4% (range 5–22%) and decreased significantly over time (P < 0.0001) while the replacement burden for PMs was constant (mean = 13.4%, range 11–16%). ICD patients had more comorbidities than PM patients (CCI: 0.8 vs 1.1, P < 0.0001). Conclusions: The replacement burden for PMs has remained constant, while the replacement burden for ICDs has decreased. This is likely due to the stability of the patient population receiving PMs and technology maturity. Alternatively, the indications for ICD implantation have broadened, resulting in an increased number of primary ICD implantations. The age and comorbidities are increasing in those patients receiving ICDs while the PM population is stable. These data suggest that monitoring of replacement burden is warranted, given the changing populations, their disparate clinical outcomes, and economic implications to the health care system. (PACE 2010; 33:705–711)     

Gender Differences in Anxiety and Concerns about the Cardioverter Defibrillator

Background: Little is known about gender differences in the response to implantable cardioverter defibrillator (ICD) therapy. We compared female and male ICD patients on anxiety, depression, health-related quality of life (HRQL), ICD concerns, and ICD acceptance.
Methods: A cohort of consecutive, surviving patients (n = 535; mean age = 61.5 ± 14.4, 81.9% male) implanted with an ICD between 1989 and 2006 completed the Hospital Anxiety and Depression Scale, the Short-Form Health Survey (SF-36), the ICD concerns questionnaire, and the Florida Patient Acceptance Survey.
Results: High levels of anxiety (52% vs 34%, P < 0.001) and ICD concerns (34% vs 16%, P = 0.001) were more prevalent in women than men, whereas no significant differences were found on depression and device acceptance (Ps > 0.05). Women were more anxious (odds ratio [OR]: 2.60 [95% confidence interval (CI): 1.46–4.64], P < 0.01) and had more ICD concerns (OR: 1.81 [95% CI: 1.09–3.00], P < 0.05) than men, adjusting for demographic and clinical characteristics. Those ICD patients experiencing shocks were also more anxious (OR: 2.02 [95% CI: 1.20–3.42], P < 0.01) and had higher levels of ICD concerns (OR: 2.70 [95% CI: 1.76–4.16], P < 0.01). In multivariable analysis of variance, significant gender differences were found for only three of the eight subscales of the SF-36 (the physical social functioning and the mental health subscale), with women reporting poorer HRQL on all three subscales.
Conclusions: Women were more prone to experience anxiety and ICD concerns compared to men regardless of whether they had experienced shocks. In clinical practice, female ICD patients should be closely monitored, and if warranted offered psychosocial intervention, as increased anxiety has been shown to precipitate arrhythmic events in defibrillator patients.     

The Psychological Impact of Implantable Cardioverter-Defibrillator Recalls and the Durable Positive Effects of Counseling

Background: It is known that patients with lifesaving devices such as implantable cardioverter-defibrillators (ICDs) may be alarmed and worried by recalls or alerts related to their ICDs.
Objectives: This study aimed to determine whether counseling has any short- or long-term benefits, and to look for characteristics that identify those most worried and those most in need of counseling.
Methods: Among 100 patients with recall or alert ICDs, 14 were pacer dependent; 50 had ICDs for 1° prevention and 22 were women. Patients completed a survey indicating how worried they were on learning of the recall or alert (0–10 scale). After counseling and advice in accordance with manufacturer guidelines, patients were asked to indicate their level of worry, and were again asked after 6 months.
Results: For all patients, the "worry level" at the initial interview was 5.0 ± 3.7, falling to 2.2 ± 3.0 after counseling (P < 0.001) and 1.4 ± 2.3 after 6 months (P < 0.001 vs both earlier levels). There were no significant differences between those implanted for 1° versus 2° prevention or for pacer dependency. Women were initially more worried than men, but not for the long term. The 49 patients whose ICDs could be managed by reprogramming or software fix had significant reduction in worry after counseling and at 6 months compared to others. The 18 patients recommended for operative intervention remained more concerned after counseling (3.5 ± 3.3 vs 1.9 ± 2.9, P = 0.043).
Conclusions: Patients' concerns resulting from ICD recalls or alerts can be reduced by appropriate counseling. Those patients whose ICDs could be reprogrammed to safer parameters had the most reduction in worry levels.     

Survival and Appropriate Device Interventions in Recipients of Cardioverter Defibrillators Implanted for the Primary Versus Secondary Prevention of Sudden Cardiac Death

Background: Implantable cardioverter-defibrillators (ICD) implanted after an episode of ventricular tachyarrhythmia (VTA) or in patients at high risk of VTA lower the long-term mortality. Comparisons of the clinical outcomes of the two indications are scarce.
Methods: The study enrolled 360 consecutive ICD recipients. The device was implanted for secondary prevention in 150 patients, whose mean age was 60 ± 14 years, and mean left ventricular ejection fraction (LVEF) was 40 ± 16%, and for primary prevention in 210 patients, whose mean age was 61 ± 11 years, and mean LVEF was 31 ± 13%. All-cause mortality and time to first appropriate ICD therapy were measured.
Results: The two study groups were similar with respect to age and prevalence of coronary artery disease. Mean LVEF was higher in the secondary prevention group (P = 0.001). Cox regression analysis revealed a significantly shorter time to first appropriate ICD therapy in the secondary prevention group (HR = 0.51, 95% CI = 0.30 – 0.87, P = 0.01). Over a mean follow-up of 37 ± 19 months, the all-cause mortality in the overall population was 12.7%, and was similar in both subgroups (HR = 0.99, 95% CI = 0.55–1.77, P = 0.97).
Conclusions: The long-term mortality in this unselected population of ICD recipients was low. Patients treated for secondary prevention received earlier appropriate ICD therapy than patients treated for primary prevention. Long-term mortality was similar in both groups. The higher VT incidence of VTA was effectively treated by the ICD and was not associated with a higher mortality.     

Impact of the Main Implantable Cardioverter-Defibrillator Trials for Primary and Secondary Prevention in Italy: A Survey of the National Activity During the Years 2001–2004

Background: Several trials demonstrated the lifesaving role of implantable cardioverter-defibrillator (ICD) in high-risk groups of patients. Aim of this review was to report the clinical characteristics of patients enrolled in the ICD Registry of the Italian Association of Arrhythmology (AIAC) in the years 2001–2004.
Methods: The Registry collects prospectively 85% of national ICD implantation activity on the basis of European ICD form (EURID).
Results: The number of implanted ICDs in Italy was 2,418 in the year 2001, 3,992 in the year 2002, 5,595 in the year 2003, and 7,190 in the year 2004. The number of ICDs per million of inhabitants was 42.1 in the year 2001 (+11.8% respect to 2000), 70.0 in the year 2002 (+65.1% respect to 2001), 98.3 in the year 2003 (+40.4% respect to 2002), and 125.0 in the year 2004 (+27.2% respect to 2003). The median age was 67 years in the years 2001–2002, 68 years in the years 2003–2004. The main indications during the study were syncope (24.2–14.9%) and cardiac arrest (28.5–17.3%), followed by palpitations and dizzy spells (15.5–17.2%, and 9.4–6.9% of patients, respectively). The use of prophylactic ICD had a fourfold increase in the examined period (5.8% in 2001, 22.9% in 2004). Ventricular tachycardia was the main arrhythmic indication in 44.4–54.6% of cases, ventricular fibrillation in 11.8–18.0%, both in 3.5–6.5%. In the years 2002, 2003, and 2004 single chamber ICDs were implanted in 45.5%, 38.8%, and 33.7% of patients, dual chamber ICDs in 35.1%, 32.3%, and 30.5%, biventricular ICDs in 19.4%, 28.9%, and 34.7%, respectively.
Conclusion: The ICD implantation rate in Italy increased significantly in the period 2001–2004, similarly to the trend in other western countries. The Registry showed an important increase of prophylactic and dual or triple chamber ICDs use.     

Detectable troponin levels predict poor prognosis in patients with left ventricular dysfunction undergoing internal defibrillator implantation

INTRODUCTION: Troponin levels have been demonstrated to predict mortality in patients with cardiomyopathy. Implantable cardiac defibrillator (ICD) devices have been demonstrated to improve survival. It is not clear if ICDs would mitigate the negative outcome predicted by elevated troponin levels. METHODS: We collected baseline blood samples for troponin T (TnT) and creatinine kinase-MB fraction in consecutive patients immediately before successful pectoral transvenous ICD implant. Patients were followed for total mortality. For analysis, patients were grouped by TnT detectability (>or=0.01 ng/mL). RESULTS: Fifty-two men, aged 68 +/- 10 years, were studied. Mean ejection fraction was 29 +/- 12% and 65% had ischemic cardiomyopathy. Follow-up duration was 17 +/- 8 months. None of the patients had abnormal creatinine kinase-MB fraction levels (1.7 +/- 1.1 ng/mL). There were 37 patients with no detectable TnT (Group I) and 15 with detectable TnT (Group II). There was no difference between the two groups in terms of age (68 vs 69, P = NS), ejection fraction (30 vs 29%, P = NS), or proportion of patients with ischemic cardiomyopathy (68 vs 60%, P = NS). During follow-up 16 (31%) patients died. Patients in group I had mortality of 16% (6/37) compared to 67% mortality (10/15, P < 0.001) in group II. On multivariate analysis, detectable TnT remained an independent predictor of mortality (HR 4.5, CI 1.4-14.25, P = 0.01). CONCLUSION: In a cohort of patients with cardiomyopathy undergoing ICD implantation for standard clinical indications, presence of detectable TnT was associated with high mortality despite ICD implantation. TnT obtained before ICD implantation may be useful for risk stratification.     

Primary Prevention Implantation of Cardioverter Defibrillator without Defibrillation Threshold Testing: 2-Year Follow-up

Background: Even though the intraoperative threshold testing of the implantable cardioverter defibrillator ( ICD ) may cause hemodynamic impairment or be unfeasible, it is still considered required standard practice at the time of implantation. We compared the outcome of ICD recipients who underwent defibrillation threshold testing (DFT) with that of patients in whom no testing was performed.
Methods: A total of 291 subjects with ischemic dilated cardiomyopathy received transvenous ICDs between January 2000 and December 2004 in five Italian cardiology centers. In two centers, DFT was routinely performed in 137 patients (81% men; mean age 69 ± 9 years; mean ejection fraction 26 ± 4%) (DFT group), while three centers never performed DFT in 154 patients (90% men; mean age 69 ± 9 years; mean ejection fraction 27 ± 5%) (no-DFT group).
Results: We compared total mortality, total cardiovascular mortality, sudden cardiac death (SCD), and spontaneous episodes of ventricular arrhythmia (sustained ventricular tachycardia, VT, and ventricular fibrillation, VF) between these groups 2 years after implantation (median 23 months, 25th–75th percentile, 12–44 months). On comparing the DFT and no-DFT groups, we found an overall mortality rate of 20% versus 16%, cardiovascular mortality of 13% versus 10%, SCD of 3% versus 0.6%, VT incidence of 8% versus 10%, and VF incidence of 6% versus 4% (no significant difference in any comparison).
Conclusions: No significant differences in the incidence of clinical outcomes considered emerged between no-DFT and DFT groups. These results should be confirmed in larger prospective studies.     

Survey of cardiac pacing and implanted defibrillator practice patterns in the United States in 1997

A survey of implanters of permanent cardiac pacemakers and ICDs in the United States during 1997 was conducted to identify present and changing patterns in indications for pacing, implantation techniques, pacing-mode selection, follow-up, and opinions regarding pacing and ICD related issues. This report is an update from 1993 of surveys performed every 4 years for the International Cardiac Pacing and Electrophysiology Society (ICPES). Questionnaires were sent to implanting physicians who were members of the North American Society of Pacing and Electrophysiology (NASPE), and who might, therefore, be expected to be more conversant than others with the state of the art. Four major manufacturers also provided estimates of the numbers of pacemakers and ICDs implanted in the United States from 1994 through 1997. In 1997, approximately 182,000 new rhythm management devices, including 153,000 primary pacing systems and 29,000 ICDs, were implanted, an increase of 24% for pacemakers and 90% for ICDs since 1994. In 1997, pacemaker implantations were performed by about 8,600 physicians working in 3,300 hospitals and 1,000 independent "surgi-centers." From 1994 to 1997, sales in the United States of dual chamber pacemakers rose from 58% to 69% of the total, and adaptive rate systems from 74% to 90%. ICD sales increased by about 29% per year from 18,700 to 35,000 units. This study disclosed significant differences among implanter subcategories and between present and earlier practices, and it provided useful insights into trends in pacemaker and defibrillator practice. Future surveys would be facilitated if a standardized implant registry like that used in Europe were established in the United States.     

Implantable Cardioverter‐Defibrillator Recipient Attitudes towards Device Deactivation: How Much do Patients Want to Know?

Background: Patients receiving implantable cardioverter‐defibrillators (ICDs) often have severely impaired left ventricular function and a poor prognosis. Having an ICD in situ effectively denies them the possibility of a quick, arrhythmic death. It is still unclear if and when the end of life and device deactivation should be discussed with patients and how much patients want to know prior to ICD implantation. Methods: Patients with an active ICD for chronic heart failure were interviewed regarding their attitude toward the ICD, their recollection of the consent procedure, and how they felt the end of life should be discussed with ICD patients (n = 54). Patients who had received ICD therapies (n = 25) were reviewed as a subgroup with extended questions regarding attitudes toward device deactivation. Results: Fifty‐four patients were recruited. Most patients were not aware that the ICD could be deactivated. The vast majority of patients (84%) wanted to be involved in the deactivation decision; 40% felt this discussion should be prior to ICD implantation but others felt the discussion should only occur if the patient was terminally ill (16%) or in the last few days of life (5%). Conclusion: Patients with ICDs are routinely counseled about the benefits of ICDs, but options for device deactivation are not well understood by patients. Most patients would like to be involved in deactivation decisions and we feel this should be discussed well in advance. (PACE 2011; 34:1628–1633)     

Safety and effectiveness of primary prevention cardioverter defibrillators in octogenarians

Background: Implantable cardioverter‐defibrillators (ICDs) reduce the rate of sudden cardiac death (SCD) in patients with cardiomyopathy and reduced left ventricular systolic function. It is unclear if this benefit extends to the very elderly patient population. Methods: Patients who underwent initial ICD implantation at age 80 or older between January 1995 and April 2010 for primary SCD prevention were identified. Clinical data were collected from the medical record, including periprocedural complications, device type, and therapies delivered. Results: Three‐hundred eighty patients were identified; 84 patients met eligibility criteria. The mean age was 82.68 years; mean follow‐up was 34 months. Mean left ventricular ejection fraction was 28.1%. Mortality during follow‐up was 17.9%. One‐ and 5‐year survival estimates were 100% and 60%, respectively. Periprocedural complications occurred in 9.4% of patients; serious complications occurred in 4.8% with no periprocedural deaths. Device therapies occurred in 11.9% (n = 10) of patients (9.5% appropriate, n = 8; 2.4% inappropriate, n = 2). Cardiac resynchronization therapy‐defibrillator (CRT‐D) implantation was associated with prolonged median survival and decreased risk of death (hazard ratio 0.212; 95% confidence interval 0.048?.942, P = 0.042) compared to ICD alone. Conclusions: Implantation of primary prevention ICDs in patients 80 years of age or older was associated with a low risk of serious complications and a 5‐year survival estimate of 60%. Inappropriate therapies after implantation were uncommon. CRT‐D implantation was associated with a decreased risk of death compared to ICD alone. These data suggest that, in selected patients in this age group, ICD implantation is safe and effective. (PACE 2011; 34:900–906)     

Analysis of Implantable Defibrillator Longevity Under Clinical Circumstances: Implications for Device Selection

Introduction: Information about implantable cardioverter‐defibrillator (ICD) longevity is mostly calculated from measurements under ideal laboratory conditions. However, little information about longevity under clinical circumstances is available. This survey gives an overview on ICD service times and generator replacements in a cohort of consecutive ICD patients. Methods: Indications for replacement were classified as a normal end‐of‐service (EOS), premature EOS, system malfunction, infection and device advisory, or recall actions. From the premature and normal EOS group, longevity from single‐chamber (SC), dual‐chamber (DC), and cardiac resynchronization therapy defibrillator (CRT‐D), rate‐responsive (RR) settings, high output (HO) stimulation, and indication for ICD therapy was compared. Differences between brands were compared as well. Results: In a total of 854 patients, 203 ICD replacements (165 patients) were recorded. Premature and normal EOS replacements consisted of 32 SC, 98 DC and 24 CRT‐D systems. Longevity was significantly longer in SC systems compared to DC and CRT‐D systems (54 ± 19 vs. 40 ± 17 and 42 ± 15 months; P = 0.008). Longevity between non‐RR (n = 143) and RR (n = 11) settings was not significantly different (43 ± 18 vs. 45 ± 13 months) as it also was not for HO versus non‐HO stimulation (43 ± 19 vs. 46 ± 17 months). Longevity of ICDs was not significantly different between primary and secondary prevention (42 ± 19 vs. 44 ± 18 months). The average longevity on account of a device‐based EOS message was 43 ± 18 months. Average longevity for Biotronik (BIO, n = 72) was 33 ± 10 months, for ELA Medical (ELA, n = 12) 44 ± 17 months, for Guidant (GDT, n = 36) 49 ± 12 months, for Medtronic (MDT, n = 29) 62 ± 22 months, and for St. Jude Medical (SJM, n = 5) 31 ± 9 months (P < 0.001). Conclusion: SC ICD generators had a longer service time compared to DC and CRT‐D systems. No influence of indication for ICD therapy and HO stimulation on generator longevity was observed in this study. MDT ICDs had the longest service time.     

Alert Tones Are Frequently Inaudible among Patients with Implantable Cardioverter-Defibrillators

Background: Current management guidelines for patients with Medtronic Sprint Fidelis ICD leads (Medtronic Inc., Minneapolis, MN, USA) include prominent use of Patient Alert™, a feature in which the ICD generator emits audible beeps at two programmable frequencies. Because hearing loss is highly prevalent beyond the sixth decade of life, the utility of this feature is unclear. Therefore, we conducted a survey of patients' ability to hear the Medtronic Patient Alert™.
Methods: During visits to an outpatient device clinic, patients with Medtronic ICDs were evaluated for their ability to hear ICD tones.
Results: The patient group consisted of 102 patients. Patients older than 70 years comprised 68% of the sample, with 16% between 60 and 70, and 17% younger than 60 years. Of the 102 patients, 59% (56% of males and 70% of females) were able to hear at least one tone. Ability to hear ICD tones decreased with advancing age. Among patients over 60 and 70 years, 52% and 43%, respectively (P < 0.001 vs. patients below 60 and 70 years), could hear at least one tone.
Conclusions: The Patient Alert™ feature is not useful among a large proportion of ICD patients. Patients with Sprint Fidelis leads should be evaluated for their ability to hear audible ICD tones. For patients who cannot hear the Patient Alert™ feature, a wireless remote monitoring and/or daily application of a magnet by a caregiver should be considered. Device manufacturers should include nonauditory alert technologies such as wireless remote monitoring and vibratory stimulation in future devices.     

Patient understanding of disease and the use and outcome of implantable cardioverter defibrillators in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in young individuals. Implantable cardioverter defibrillators (ICD) are the primary therapy for sudden death prevention; however, are associated with both physical and psychological complications. We sought to determine factors associated with ICD understanding and patient satisfaction. This was a cross‐sectional study, using patient/parent answered questionnaires distributed to patients enrolled in the Hypertrophic Cardiomyopathy Association. Patient characteristics and satisfaction data were obtained via questionnaire. Patients were compared based on age at diagnosis and presence of ICD. ICD patients with high satisfaction were compared to those with low satisfaction to determine factors associated with poor satisfaction. A total of 538 responses were obtained (53 ± 16 years); 46% were females. Seventy patients (13%) were diagnosed with HCM < 18 years of age and 356 (66%) had an ICD. Compared to those without an ICD, patients with ICDs were younger at age of diagnosis (P = 0.001) and time of study (P = 0.008). Patients with ICDs were more likely to have presented with syncope and have family history of ICD, SCD, or HCM‐related death. Nineteen patients (5%) felt that issues surrounding their ICD outweighed its benefit. Compared to patients with a favorable satisfaction, the only significant difference was the preimplant ICD discussion (P < 0.001) and history of lead replacement (P = 0.01). In conclusion, the majority of HCM patients with ICDs are satisfied with their ICD management and feel the benefits of ICDs outweigh issues associated with ICDs. Additionally, these data highlight the importance of the preimplant patient‐physician discussion around the need for ICD prior to implantation.     

Distinct clinical features in the recipients of the implantable cardioverter defibrillator in Taiwan: a multicenter registry study

Little information about the ICD is available from the Asian Pacific region. The purpose of this study was to characterize the clinical features in ICD patients in Taiwan and to compare these features with those in patients in the Western populations, mainly the Canadian Implantable Defibrillator Study (CIDS), the Antiarrhythmics versus Implantable Defibrillator (AVID) trial, and the Cardiac Arrest Study Hamburg (CASH) trial. From February 1995 to October 2001, 101 ICDs were implanted in 92 patients (78 [84%] men) in 12 hospitals. Clinical presentations included sudden cardiac death due to VF/VT in 35 (38%) patients, syncopal VT in 25 (27%), drug refractory nonsyncopal VT in 27 (29%), and unexplained syncope with inducible sustained VT/VF in 5 (6%). The mean age was significantly younger than that in CIDS or AVID (59 +/- 16 vs 63 +/- 9 years in CIDS, P = 0.02; vs 65 +/- 11 years in AVID, P < 0.001), but was comparable to that in CASH (59 +/- 16 vs 58 +/- 11 years in CASH, P = 0.75). The mean LVEF was significantly higher than that in CIDS or AVID (48 +/- 19% vs 34 +/- 15% in CIDS, P < 0.001; vs 32 +/- 13% in AVID, P < 0.001), but was comparable to that in CASH (48 +/- 19 vs 46 +/- 19% in CIDS, P = 0.83). The ICD patients in the current study also showed a higher incidence of normal heart (23 vs 4% in CIDS, P < 0.001; vs 3% in AVID, P < 0.001; vs 9% in CASH, P < 0.001) and cardiomyopathy (41% vs 10% in CIDS, P < 0.001; vs 15% in AVID, P < 0.001; vs 11% in CASH, P < 0.001), but a lower incidence of coronary artery disease (29% vs 83% in CIDS, P < 0.001; vs 82% in AVID, P < 0.001; vs 73% in CASH, P < 0.001). During a mean follow-up of 28 +/- 24 months, 13 (14%) patients died. Older age was the only factor associated with poorer survival after ICD implantation. Forty-seven (51%) patients received appropriate ICD discharges during follow-up. History of prior myocardial infarction was the only factor associated with an earlier first appropriate ICD discharge and LVEF < 0.35 the only factor associated with subsequent poorer survival after the first ICD discharge. In conclusion, this study demonstrated many distinct clinical features in our ICD population that were different from those in the Western populations.     

Feasibility of implantable cardioverter defibrillator use in elderly patients: a case series of octogenarians

This article addresses the feasibility and safety of ICD therapy in patients >80 years of age. Recent trials have expanded the indication for ICD implantation to include an increasing number and variety of patients. The feasibility of ICD implantation in elderly patients has not been adequately studied. A prospectively collected single center ICD database was analyzed to assess the safety and feasibility of ICD implantation in elderly patients. Patients were divided based on age into two groups (group 1: 70-79 years of age, n = 183; group 2: >or=80 years of age, n = 29). The two groups were similar in gender distribution, NYHA class, and indication for implantation. The actuarial survival was not significantly different between groups 1 and 2 (P > 0.05; primary endpoint), with a 1-year survival of 91% and 93% in groups 1 and 2, respectively, (P = NS). The complication rates at the time of ICD implantation were similar in groups 1 and 2 (6.6% and 13.1%, respectively, P = 0.16). Age alone may not be sufficient criteria to exclude ICD implantation. The current consensus guidelines for ICD implantation appear to be generalizable to treating octogenarians who are otherwise medically fit.     

ECG Quantification of Myocardial Scar Does Not Differ between Primary and Secondary Prevention ICD Recipients with Ischemic Heart Disease

Background: Myocardial scar is an anatomic substrate for potentially lethal arrhythmias. Recent study showed that higher QRS‐estimated scar size using the Selvester QRS score was associated with increased arrhythmogenesis during electrophysiologic testing. Therefore, QRS scoring might play a potential role in risk stratification before implantable cardioverter defibrillator (ICD) implantation. In this study, we tested the hypothesis that QRS scores among ICD recipients for secondary prevention are higher than QRS scores in primary prevention patients. Methods and Results: From the hospital database, 100 consecutive patients with ischemic heart disease and prior ICD implantation were selected. Twelve‐lead electrocardiograms (ECGs) had been obtained before implantation. ECGs were scored following the 32‐points Selvester QRS scoring system and corrected for underlying conduction defects and/or hypertrophy. Ninety‐three ECGs were suitable for scoring; seven ECGs were rejected because of noise, missing leads, excessive ventricular extrasystoles, or ventricular pacing. No statistically significant difference in QRS score was found between the primary [6.90 (standard deviation [SD] 3.94), n = 63] and secondary prevention group [6.17 (SD 4.50) (P = 0.260), n = 30]. Left ventricular ejection fraction (LVEF) was significantly higher in the secondary prevention group [31% (SD 13.5) vs 24% (SD 11.7) (P = 0.015)]. When patients with LVEF ≥35% were excluded, QRS scores were still comparable, namely 7.02 (SD 4.04) in the primary prevention group (n = 52) and 6.28 (SD 4.24) in the secondary (P = 0.510) (n = 18). Conclusion: We found no significant difference in QRS score between the ischemic primary and secondary prevention groups. Therefore, a role of the Selvester QRS score as a risk stratifier remains unlikely. (PACE 2010; 33:192–197)     

Defibrillation Threshold Testing in Patients with Hypertrophic Cardiomyopathy

Introduction: Implantable cardioverter‐defibrillators (ICDs) decrease sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). One of the vital aspects of ICD implantation is the demonstration that the myocardium can be reliably defibrillated, which is defined by the defibrillation threshold (DFT). We hypothesized that patients with HCM have higher DFTs than patients implanted for other standard indications. Methods: We retrospectively reviewed the medical records of patients implanted with an ICD at the University of Maryland from 1996 to 2008. All patients with HCM who had DFTs determined were included. Data were compared to selected patients implanted for other standard indications over the same time period. All patients had a dual‐coil lead with an active pectoral can system and had full DFT testing using either a step‐down or binary search protocol. Results: The study group consisted of 23 HCM patients. The comparison group consisted of 294 patients. As expected, the HCM patients were younger (49 ± 18 years vs 63 ± 12 years; P < 0.00001) and had higher left ventricular ejection fractions (66% vs 32%; P < 0.000001). The average DFT in the HCM group was 13.9 ± 7.0 Joules (J) versus 9.8 ± 5.1 J in the comparison group (P = 0.0004). In the HCM group, five of the 23 patients (22%) had a DFT ≥ 20 J compared to 19 of 294 comparison patients (6%). There was a significant correlation between DFT and left ventricle wall thickness in the HCM group as measured by echocardiography (r = 0.44; P = 0.03); however, there was no correlation between DFT and QRS width in the HCM group (r = 0.1; P = NS). Conclusions: Our results suggest that patients with HCM have higher DFTs than patients implanted with ICDs for other indications. More importantly, a higher percentage of HCM patients have DFTs ≥ 20 J and the DFT increases with increasing left ventricle wall thickness. These data suggest that DFT testing should always be considered after implanting ICDs in HCM patients. (PACE 2010; 1342–1346)     

Incidence and Characteristics of Appropriate and Inappropriate Therapies in Recipients of ICD Implanted for Primary Prevention of Sudden Cardiac Death

Background: We evaluated the number of appropriate and inappropriate therapies for ventricular tachyarrhythmias and trigger mechanisms in 55 MADIT II (MII)-like (group 1) and 86 SCD-HeFT-like (group 2) patients.
Methods and Results: We analyzed 399 appropriate episodes in 31 patients with implantable cardioverter defibrillators (ICD) implanted according to the MII trial indications, and 502 appropriate episodes in 47 patients matching the SCD-HeFT trial criteria (mean follow-up in both groups = 33 ± 19 months). In group 1, 39 treated episodes were inappropriate (9% of all episodes), while in group 2, 76 episodes were treated inappropriately (15% of all episodes). At least one episode of inappropriate ICD therapy was recorded in 18% of patients in group 1 (n = 10) and in 22% of patients in group 2 (n = 19).
Conclusions: Our study supports the implantation of ICD as primary prevention in patients who are at risk of sudden cardiac death, although the proportion of inappropriate ICD interventions remains high.