Risk factors for appropriate cardioverter-defibrillator shocks, inappropriate cardioverter-defibrillator shocks, and time to mortality in 549 patients with heart failure

Effect of Digitalis on ICD or CRT-D Recipients: A Systematic Review and Meta-Analysis

BACKGROUND

Digitalis has been widely utilized for heart failure therapy and several studies have demonstrated an association of digitalis and adverse outcome events in patients receiving implantable cardioverter defibrillators (ICDs) or cardiac resynchronization therapy defibrillators (CRT-Ds). Hence, we conducted this meta-analysis to assess the effect of digitalis on ICD or CRT-D recipients.

METHODS

We systematically retrieved relevant studies using the Cochrane Library, PubMed, and Embase database. A random effect model was used to pool the effect estimates (hazard ratios (HRs) and 95% confidence intervals (CIs)) when the studies were of high heterogeneity, otherwise a fixed effect model was used.

RESULTS

Twenty-one articles containing 44,761 ICD or CRT-D recipients were included. Digitalis was associated with an increased rate of appropriate shocks (HR = 1.65, 95% CI: 1.46-1.86, p < 0.001) and a shortened time to first appropriate shock (HR = 1.76, 95% CI: 1.17-2.65, p = 0.007) in ICD or CRT-D recipients. Furthermore, the all-cause mortality increased in ICD recipients with digitalis therapy (HR = 1.70, 95% CI: 1.34-2.16, p < 0.01), but the all-cause mortality was unchanged in CRT-D recipients (HR = 1.55, 95% CI: 0.92-2.60, p = 0.10) or patients who received ICD or CRT-D therapy (HR = 1.09, 95% CI: 0.80-1.48, p = 0.20). The sensitivity analyses confirmed the robustness of the results.

CONCLUSION

ICD recipients with digitalis therapy may tend to have higher mortality rates, but digitalis may not be associated with the mortality rate of CRT-D recipients. Further studies are required to confirm the effects of digitalis on ICD or CRT-D recipients.

Influence of diabetes on mortality and ICD therapies in ICD recipients: a systematic review and meta-analysis of 162,780 patients

Background

The influence of diabetes on the mortality and risk of implantable cardioverter defibrillator (ICD) therapies is still controversial, and a comprehensive assessment is lacking. We performed this systematic review and meta-analysis to address this controversy.

Methods

We systematically searched the PubMed, Embase, Web of Science and Cochrane Library databases to collect relevant literature. Fixed and random effects models were used to estimate the hazard ratio (HR) with 95% CIs.

Results

Thirty-six articles reporting on 162,780 ICD recipients were included in this analysis. Compared with nondiabetic ICD recipients, diabetic ICD recipients had higher all-cause mortality (HR = 1.45, 95% CI 1.36–1.55). The subgroup analysis showed that secondary prevention patients with diabetes may suffer a higher risk of all-cause mortality (HR = 1.89, 95% CI 1.56–2.28) (for subgroup analysis, P = 0.03). Cardiac mortality was also higher in ICD recipients with diabetes (HR = 1.68, 95% CI 1.35–2.08). However, diabetes had no significant effect on the risks of ICD therapies, including appropriate or inappropriate therapy, appropriate or inappropriate shock and appropriate anti-tachycardia pacing (ATP). Diabetes was associated with a decreased risk of inappropriate ATP (HR = 0.56, 95% CI 0.39–0.79).

Conclusion

Diabetes is associated with an increased risk of mortality in ICD recipients, especially in the secondary prevention patients, but does not significantly influence the risks of ICD therapies, indicating that the increased mortality of ICD recipients with diabetes may not be caused by arrhythmias. The survival benefits of ICD treatment in diabetes patients are limited.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-022-01580-y.

Selvester score predicts implantable cardioverter defibrillator shocks in patients with non-ischemic cardiomyopathy

BACKGROUND

The implantable cardiac defibrillator is the cornerstone of prevention of sudden cardiac death in non-ischemic cardiomyopathy. The Selvester score, which is frequently investigated in ischemic cardiomyopathy, has not been investigated in the field of non-ischemic cardiomyopathy.

AIM

The aim of this study was to evaluate the Selvester score for determining appropriate implantable cardiac defibrillator shocks in non-ischemic cardiomyopathy patients.

MATERIALS AND METHODS

In all, 131 non-ischemic cardiomyopathy patients were included in the study. A simplified Selvester score was calculated from ECG data. Patients were divided into two groups according to whether they received ICD shock.

RESULTS

Of the patients, 28.2% received appropriate implantable cardiac defibrillator shock. The Selvester score was significantly higher in patients receiving appropriate shock when compared to patients with no implantable cardiac defibrillator shocks (8.8 ± 4.6 vs 7.2 ± 3.3, P = .040). The median QRS duration was significantly longer in patients receiving appropriate shock than in patients with no shocks (130.14 ± 35.08 ms vs 120.12 ± 20.57 ms, P = .045). We determined that the cutoff value for the Selvester score to predict ICD shocks was 6.5 with a sensitivity of 72.0% and a specificity of 83% (AUC = 0.717; %95 GA: 0.627-0.807, P < .001).

CONCLUSION

Selvester score was higher in patients receiving appropriate shock than in patients who did not receive any implantable cardiac defibrillator shock. From this study, the Selvester score is associated with the risk of ventricular tachycardia/ventricular fibrillation in non-ischemic cardiomyopathy so that careful attention is necessary to manage the patients with high Selvester score.

Validity Evidence of the Brazilian Version of the Florida Shock Anxiety Scale for Patients with Implantable Cardioverter Defibrillators

BACKGROUND

In spite of proven effectiveness of implantable cardioverter defibrillators (ICDs), shock therapy delivered by the device may result in increased levels of anxiety and depression, leading to deleterious effects on quality of life.

OBJECTIVE

To carry out the translation, cross-cultural adaptation and validation of the Florida Shock Anxiety Scale (FSAS) scale into Brazilian Portuguese.

METHODS

In this psychometric study, construct validity was performed by exploratory (EFA) and confirmatory (CFA) factor analyses, and by item response theory (IRT). The adjustment indexes of the CFA were: Robust Mean-Scaled Chi Square/df NNFI, CFI (Comparative Fit Index), GFI (Goodness Fit Index), AGFI (Adjusted Goodness Fit Index), RMSEA (Root Mean Square Error of Approximation) and RMSR (Root Mean Square of Residuals). Reliability was evaluated through Cronbach's Alpha, McDonald's Omega and Greatest Lower Bound (GLB). The analyses were carried out with the programs SPSS 23 and Factor 10.8.01. A 5 percent significance level was used.

RESULTS

The final Portuguese version of the FSAS was administered to 151 ICD patients, with a mean age of 55.7 ± 14.1 years, and predominantly male. The parallel analysis indicated that the FSAS is unidimensional, with an explained variance of 64.4%. The correlations ranged from 0.31 to 0.77, factor loadings from 0.67 to 0.86, and communalities from 0.46 to 0.74. The adjustment indexes of the CFA were above the quality threshold. Satisfactory reliability evidence was provided by the FSAS.

CONCLUSIONS

The FSAS-Br showed consistent validity and reliability evidence. Therefore, it can be used in ICD patients in Brazil. (Arq Bras Cardiol. 2020; 114(5):764-772).

Atrial Fibrillation Is Associated With Higher Overall Mortality in Patients With Implantable Cardioverter-Defibrillator: A Systematic Review and Meta-Analysis

Background Implantable cardioverter-defibrillator ( ICD ) improves survival when used for primary or secondary prevention of sudden cardiac death. Whether the benefits of ICD in patients with atrial fibrillation ( AF) are similar to those with normal sinus rhythm ( NSR ) is not well established. The aim of this study is to investigate whether ICD patients with AF are at higher risk of mortality and appropriate shock therapy compared with patients with NSR . Methods and Results Literature was searched and 25 observational studies with 63 283 patients were included in this meta-analysis. We compared the outcomes of (1) all-cause mortality and appropriate shock therapy among AF and NSR patients who received ICD for either primary or secondary prevention and (2) all-cause mortality among AF patients with ICD versus guideline directed medical therapy. All-cause mortality (odds ratio, 2.11; 95% confidence interval, 1.73-2.56; P<0.001) and incidence of appropriate shock therapy (odds ratio, 1.77; 95% confidence interval, 1.47-2.13; P<0.001) were significantly higher in ICD patients with AF as compared to NSR . There was no statistically significant mortality benefit from ICD compared with medical therapy in AF patients (odds ratio, 0.69; 95% confidence interval, 0.42-1.11; P=0.12) based on a separate meta-analysis of 3 studies with 387 patients. Conclusions Overall mortality and appropriate shock therapy are higher in ICD patients with AF as compared with NSR . The impact of ICD on all-cause mortality in AF patients when compared to goal-directed medical therapy is unclear, and randomized controlled trials are needed comparing AF patients with ICD and those who have indications for ICD, but are only on medical therapy.

Drug Therapy of Dyslipidemia in the Elderly

Abnormal lipoprotein metabolism is an important and modifiable risk factor for atherosclerotic cardiovascular disease (ASCVD), which has been shown in numerous studies to lead to adverse cardiovascular outcomes. As cardiovascular disease (CVD) remains the major cause of morbidity and mortality globally, management of dyslipidemia is a key component of primary and secondary risk-reduction strategies. Because ASCVD risk increases with age, as the population ages, many more people-particularly the elderly-will meet guideline criteria for drug treatment. Statins (HMG-CoA reductase inhibitors) have an unequivocal benefit in reducing ASCVD risk across age groups for secondary prevention. However, the benefit of these drugs for primary prevention in those > 75 years of age remains controversial. We strongly believe that statins should be offered for primary prevention to all older individuals after a shared decision-making process that takes polypharmacy, frailty, and potential adverse effects into consideration. When considering statin therapy in the very old, competing risks of death, and therefore the likelihood that patients will live long enough to benefit from drug therapy, should inform this process. Combination therapies with ezetimibe or proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors should be considered to facilitate the use of tolerable doses of statins. Future investigations of dyslipidemia therapies must appropriately include this at-risk population to identify optimal drugs and drug combinations that have a high benefit:risk ratio for the prevention of ASCVD in the elderly.

Influence of Multimorbidity on Burden and Appropriateness of Implantable Cardioverter-Defibrillator Therapies

OBJECTIVE

To determine whether burden of multiple chronic conditions (MCCs) influences the risk of receiving inappropriate vs appropriate device therapies.

DESIGN

Retrospective cohort study.

SETTING

Seven US healthcare delivery systems.

PARTICIPANTS

Adults with left ventricular systolic dysfunction receiving an implantable cardioverter-defibrillator (ICD) for primary prevention.

MEASUREMENTS

Data on 24 comorbid conditions were captured from electronic health records and categorized into quartiles of comorbidity burden (0-3, 4-5, 6-7 and 8-16). Incidence of ICD therapies (shock and antitachycardia pacing [ATP] therapies), including appropriateness, was collected for 3 years after implantation. Outcomes included time to first ICD therapy, total ICD therapy burden, and risk of inappropriate vs appropriate ICD therapy.

RESULTS

Among 2235 patients (mean age = 69 ± 11 years, 75% men), the median number of comorbidities was 6 (interquartile range = 4-8), with 98% having at least two comorbidities. During a mean 2.2 years of follow-up, 18.3% of patients experienced at least one appropriate therapy and 9.9% experienced at least one inappropriate therapy. Higher comorbidity burden was associated with an increased risk of first inappropriate therapy (adjusted hazard ratio [HR] = 1.94 [95% confidence interval {CI} = 1.14-3.31] for 4-5 comorbidities; HR = 2.25 [95% CI = 1.25-4.05] for 6-7 comorbidities; and HR = 2.91 [95% CI = 1.54-5.50] for 8-16 comorbidities). Participants with 8-16 comorbidities had a higher total burden of ICD therapy (adjusted relative risk [RR] = 2.12 [95% CI = 1.43-3.16]), a higher burden of inappropriate therapy (RR = 3.39 [95% CI = 1.67-6.86]), and a higher risk of receiving inappropriate vs appropriate therapy (RR = 1.74 [95% CI = 1.07-2.82]). Comorbidity burden was not significantly associated with receipt of appropriate ICD therapies. Patterns were similar when separately examining shock or ATP therapies.

CONCLUSIONS

In primary prevention ICD recipients, MCC burden was independently associated with an increased risk of inappropriate but not appropriate device therapies. Comorbidity burden should be considered when engaging patients in shared decision making about ICD implantation.

Beta-blocker therapy reduces mortality in patients with coronary artery disease treated with percutaneous revascularization: a meta-analysis of adjusted results

AIMS

The long-term impact of beta blockers on prognosis in patients treated with contemporary therapies for coronary artery disease remains to be defined.

METHODS AND RESULTS

All observational studies evaluating the impact of beta blockers in patients treated with coronary revascularization and contemporary therapies and adjusted with multivariate analysis were included. All-cause death was the primary endpoint, while Major Adverse Cardiac Events (MACE) (composite endpoint of all-cause death or myocardial infarction, MI) and MI were secondary endpoints. A total of 26 studies were included, with 863 335 patients. After 3 (1-4.3) years, long-term risk of all-cause death was lower in patients on beta blockers [odds ratio, OR 0.69 (0.66-0.72)], both for Acute Coronary Syndrome (ACS) [OR 0.60 (0.56-0.65)], and stable angina patients [OR 0.84 (0.78-0.91)], independently from ejection fraction [OR 0.64 (0.42-0.98) for reduced ejection fraction and OR 0.79 (0.69-0.91) for preserved ejection fraction]. The risk of long-term MACE was lower but NS for ACS patients treated with beta blockers [OR 0.83 (0.69-1.00)], as in stable angina. Similarly, risk of MI did not differ between patients treated with beta blockers or without beta blockers [OR 0.99 (0.89-1.09), all 95% confidence intervals]. Using meta-regression analysis, the benefit of beta blockers was increased for those with longer follow-up. The number needed to treat was 52 to avoid one event of all-cause death for ACS patients and 111 for stable patients.

CONCLUSION

Even in percutaneous coronary intervention era, beta blockers reduce mortality in patients with coronary artery disease, confirming their protective effect, which was consistent for both ACS and stable patients indifferently of preserved or reduced ejection fraction.

Impact of statin therapy on all-cause mortality and ICD interventions in heart failure patients - a systematic review

OBJECTIVES

Implantable cardioverter defibrillators (ICDs) have a unique role for the primary and secondary prevention of sudden cardiac death (SCD). The aim of our systematic review is to present the existing data about the impact of statins on all-cause mortality and ICD interventions in heart failure (HF) patients who had an ICD implanted either for primary or for secondary prevention of SCD.

METHODS AND RESULTS

We searched PubMed database and the reference list of the relevant studies for retrieving studies evaluating the effect of statins on all-cause mortality and ICD interventions in HF patients. We finally included 17 relevant studies in our systematic review. Of them, nine studies included data about the impact of statins on all-cause mortality, eight studies about the impact of statins on appropriate ICD interventions and three studies about the impact of statins on inappropriate ICD interventions in HF patients. These data showed that statins seem to have a beneficial role in the reduction of all-cause mortality and ICD interventions in HF patients.

CONCLUSIONS

Statins seem to have a beneficial role in the reduction of all-cause mortality and ICD interventions in HF patients. However, further research about pleiotropic effects of statins is needed as well randomized control trials to elucidate the exact role of statin therapy in ICD outcomes.

Cardiovascular effects of electronic cigarettes

Cardiovascular safety is an important consideration in the debate on the benefits versus the risks of electronic cigarette (EC) use. EC emissions that might have adverse effects on cardiovascular health include nicotine, oxidants, aldehydes, particulates, and flavourants. To date, most of the cardiovascular effects of ECs demonstrated in humans are consistent with the known effects of nicotine. Pharmacological and toxicological studies support the biological plausibility that nicotine contributes to acute cardiovascular events and accelerated atherogenesis. However, epidemiological studies assessing Swedish smokeless tobacco, which exposes users to nicotine without combustion products, generally have not found an increased risk of myocardial infarction or stroke among users, but suggest that nicotine might contribute to acute cardiovascular events, especially in those with underlying coronary heart disease. The effects of aldehydes, particulates, and flavourants derived from ECs on cardiovascular health have not been determined. Although ECs might pose some cardiovascular risk to users, particularly those with existing cardiovascular disease, the risk is thought to be less than that of cigarette smoking based on qualitative and quantitative comparisons of EC aerosol versus cigarette smoke constituents. The adoption of ECs rather than cigarette smoking might, therefore, result in an overall benefit for public health.

Treatment of Hypercholesterolemia in 2015

Randomized, double-blind, placebo-controlled secondary prevention and primary prevention studies and observational studies have documented that statins reduce cardiovascular events in high-risk patients with hypercholesterolemia. The 2013 American College of Cardiology/American Heart Association guidelines on treatment of hypercholesterolemia support the use of statins in 4 major groups that will be discussed. The Expert Panel of these guidelines could find no data supporting the routine use of nonstatin drugs combined with statins to further reduce cardiovascular events. Since these guidelines were published, a double-blind randomized trial of 18,144 patients with an acute coronary syndrome demonstrated at a 7-year follow-up that the incidence of cardiovascular events was 34.7% in patients randomized to simvastatin plus placebo versus 32.7% in patients randomized to simvastatin plus ezetimibe (hazard ratio = 0.936; P = 0.016). Proprotein convertase subtilisin/kexin type 9 inhibitors further lower serum low-density lipoprotein cholesterol by 50%-70% in patients treated with statins and 4 phase 3 trials including more than 70,000 patients are investigating whether these monoclonal antibodies to proprotein convertase subtilisin/kexin type 9 will lower cardiovascular events.

Differences Between Access to Follow-Up Care and Inappropriate Shocks Based on Insurance Status of Implantable Cardioverter Defibrillator Recipients

Differences in implantable cardioverter defibrillator (ICD) utilization based on insurance status have been described, but little is known about postimplant follow-up patterns associated with insurance status and outcomes. We collected demographic, clinical, and device data from 119 consecutive patients presenting with ICD shocks. Insurance status was classified as uninsured/Medicaid (uninsured) or private/Health Maintenance Organization /Medicare (insured). Shock frequencies were analyzed before and after a uniform follow-up pattern was implemented regardless of insurance profile. Uninsured patients were more likely to present with an inappropriate shock (63% vs 40%, p = 0.01), and they were more likely to present with atrial fibrillation (AF) as the shock trigger (37% vs 19%, p = 0.04). Uninsured patients had a longer interval between previous physician contact and index ICD shock (147 ± 167 vs 83 ± 124 days, p = 0.04). Patients were followed for a mean of 521 ± 458 days after being enrolled in a uniform follow-up protocol, and there were no differences in the rate of recurrent shocks based on insurance status. In conclusion, among patients presenting with an ICD shock, underinsured/uninsured patients had significantly longer intervals since previous physician contact and were more likely to present with inappropriate shocks and AF, compared to those with private/Medicare coverage. After the index shock, both groups were followed uniformly, and the differences in rates of inappropriate shocks were mitigated. This observation confirms the importance of regular postimplant follow-up as part of the overall ICD management standard.

Lipid-lowering therapy in older persons

Numerous randomized, double-blind, placebo-controlled studies and observational studies have shown that statins reduce mortality and major cardiovascular events in older high-risk persons with hypercholesterolemia. The Heart Protection Study showed that statins reduced mortality and major cardiovascular events in high-risk persons regardless of the initial level of serum lipids, age, or gender. The updated National Cholesterol Education Program III guidelines state that in very high-risk persons, a serum low-density lipoprotein (LDL) cholesterol level of < 70 mg/dl (1.8 mmol/l) is a reasonable clinical strategy for moderately high-risk persons (2 or more risk factors and a 10-year risk for coronary artery disease of 10% to 20%), and the serum LDL cholesterol should be reduced to < 100 mg/dl (2.6 mmol/l). When LDL cholesterol-lowering drug therapy is used to treat high-risk persons or moderately high-risk persons, the serum LDL cholesterol should be reduced by at least 30% to 40%. The serum LDL cholesterol should be decreased to less than 160 mg/dl in persons at low risk for cardiovascular disease. Addition of other lipid-lowering drugs to statin therapy has not been demonstrated to further reduce cardiovascular events and mortality.

Inappropriate shock for myopotential over-sensing in a patient with subcutaneous ICD

Inappropriate ICD shocks are common adverse events; they are mainly due to supraventricular arrhythmias and secondly are related to noise, undersensing, oversensing, device malfunctions. We present a case of inappropriate device therapy due to myopotential oversensing in a patient with a subcutaneous ICD (s-ICD). A 58 years old male with an s-ICD during the device interrogation showed a previous episode of suspected sustained ventricular tachycardia at 210 bpm, which was effectively treated with ICD shock. The patient experienced the electrical shock while holding a big gas-cylinder in his arms. The EGM analysis revealed many irregular ventricular signals of low amplitude lasting for 24 s and interrupted by the shock. The device showed no malfunctions. This is the first case report of inappropriate S-ICD shock related to myopotential over-sensing. By recording intracardiac EGM, we demonstrated that the noise was created by the activity of the pectorals muscles.

Sleep-disordered breathing and inappropriate defibrillator shocks in chronic heart failure

PURPOSE

Supraventricular tachyarrhythmias are a major cause of inappropriate defibrillator shocks. Sleep-disordered breathing (SDB) is a known risk factor for atrial fibrillation (AF). We hypothesized that Cheyne-Stokes respiration (CSA) and obstructive sleep apnea (OSA) have an impact on inappropriate defibrillator discharges in patients witch chronic heart failure (CHF) and cardiac resynchronization therapy with defibrillator (CRT-D).

METHODS

In this study, 172 patients with CHF (LVEF ≤ 45 %, NYHA-class ≥ 2) and CRT-D underwent overnight polygraphy; 54 had no SDB (apnea-hypopnea index < 5/h), 59 had OSA, and 59 had CSA. During follow-up (36 months), inappropriate defibrillator shocks were documented.

RESULTS

In all, 17 patients had inappropriate defibrillator shocks (9.9 %; eight oversensing due to lead fractures, five caused by atrial fibrillation, four because of sinus tachycardia). Mean event-free survival time was 33.5 ± 1.2 months in the CSA group, 35.2 ± 0.7 months in the OSA group, and 32.1 ± 1.5 months in the no SDB group, respectively (CSA vs. no SDB p = 0.63; OSA vs. no SDB p = 0.31; CSA vs. OSA p = 0.45). Stepwise Cox proportional hazard regression analysis revealed an independent association for age (per year: hazard ratio 0.90, 95 % confidence interval 0.85-0.96, p < 0.001), but not for any kind of SDB.

CONCLUSIONS

SDB was not associated with inappropriate defibrillator shocks. We assume this is due to the low incidenceand low proportion of inappropriate therapies in response to AF.

Cardiovascular effects of statins, beyond lipid-lowering properties

The 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, better known as 'statins', are amongst the most widely used medications in the world. They have become a pivotal component in the primary and secondary prevention of coronary artery and vascular disease. However, a growing amount of evidence has suggested that statins also possess strong pleiotropic effects irrespective of their lipid-lowering properties, which include enhancement of endothelial function, anti-inflammatory and anti-atherothrombotic properties, and immunomodulation. The following provides a comprehensive and updated review of the clinical evidence regarding the pleiotropic effects of statins in cardiovascular disorders and their potential therapeutic benefits.

Atrial fibrillation in cardiac resynchronization therapy with a defibrillator: a risk factor for mortality, appropriate and inappropriate shocks

INTRODUCTION

Knowledge about predictive factors for mortality and (in)appropriate shocks in cardiac resynchronization therapy with a defibrillator (CRT-D) should be available and updated to predict clinical outcome.

METHODS

We retrospectively analyzed 543 consecutive patients assigned to CRT-D in 2 tertiary medical centers. The aim of this study was to assess risk factors for all-cause mortality, appropriate and inappropriate shocks.

RESULTS

Mean follow-up time was 3.2 (±1.8) years. A total of 110 (20%) patients died, 71 (13%) received ≥1 appropriate shocks, and 33 (6.1%) received ≥1 inappropriate shocks. No patients received a His bundle ablation and biventricular pacing percentage was not analyzed. Multivariable Cox regression analysis showed that a history of atrial fibrillation (AF) (HR 1.74 CI 1.06-2.86), higher creatinine (HR 1.12; CI 1.08-1.16), and a poorer left ventricular ejection fraction (LVEF) (HR 0.97; CI 0.94-1.01) independently predict all-cause mortality. In the entire cohort, history of AF and secondary prevention were independent predictors of appropriate shocks and variables associated with inappropriate shocks were history of AF and QRS ≥150 milliseconds. In primary prevention patients, history of AF also predicted appropriate shocks as did ischemic cardiomyopathy and poorer LVEF. History of AF, QRS ≥150 milliseconds, and lower creatinine were associated with inappropriate shocks in this subgroup. Appropriate shocks increased mortality risk, but inappropriate shocks did not.

CONCLUSION

In symptomatic CHF patients treated with CRT-D, history of AF is an independent risk factor not only for mortality, but also for appropriate and inappropriate shocks. Further efforts in AF management may optimize the care in CRT-D patients.

Influence of diabetes mellitus on inappropriate and appropriate implantable cardioverter-defibrillator therapy and mortality in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) Trial

BACKGROUND

The relationship between diabetes mellitus and risk of inappropriate or appropriate therapy in patients receiving an implantable cardioverter-defibrillator (ICD) and resynchronization therapy has not been investigated thoroughly. The effect of innovative ICD programming on therapy delivery in these patients is unknown.

METHODS AND RESULTS

The Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) randomized patients with a primary prophylactic ICD indication to 3 different types of ICD programming: conventional programming with a ventricular tachycardia zone of 170 to 199 bpm (arm A), high-rate cutoff with a ventricular tachycardia zone ≥200 bpm (arm B), or 60-second-delayed therapy (arm C). The end points of inappropriate therapy, appropriate therapy, and death were assessed among 485 patients with and 998 without diabetes mellitus. Innovative ICD programming reduced the risk of inappropriate therapy regardless of diabetes mellitus, although a trend toward a more pronounced effect of high-rate cutoff programming was seen in patients without diabetes mellitus (P for interaction=0.06). Diabetes mellitus was associated with a decreased risk of inappropriate therapy (hazard ratio, 0.54; 95% confidence interval, 0.36-0.80; P=0.002) and increased risk of appropriate therapy (hazard ratio, 1.58; 95% confidence interval, 1.17-2.14; P=0.003). In diabetic patients, there was significantly increased risk of death in those who had inappropriate therapy (hazard ratio, 4.17; 95% confidence interval, 1.52-11.40; P=0.005) and appropriate therapy (hazard ratio, 2.49; 95% confidence interval, 1.06-5.87; P=0.037) compared with those who did not.

CONCLUSIONS

Innovative high-rate cutoff or delayed ICD programming was associated with a reduction in inappropriate therapy in patients with and without diabetes mellitus. Diabetes mellitus was associated with lower risk of inappropriate therapy but higher risk of appropriate therapy. Appropriate and inappropriate ICD therapy was associated with increased mortality in diabetic patients.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. UNIQUE IDENTIFIER: NCT00947310.

Usefulness of sleep-disordered breathing to predict occurrence of appropriate and inappropriate implantable-cardioverter defibrillator therapy in patients with implantable cardioverter-defibrillator for primary prevention of sudden cardiac death

Advanced heart failure (HF) is associated with severe sleep-disordered breathing (SDB). In addition, most patients with HF are treated with an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death. The incidence of ICD therapy in such a patient cohort with SDB has never been investigated. The present study sought to determine the effect of SDB on the incidence of appropriate and inappropriate ICD therapy in patients with a categorical primary prevention ICD indication. A total of 133 consecutive ICD patients with New York Heart Association class II-III HF and depressed left ventricular function (≤35%) with no history of ventricular arrhythmia underwent a sleep study before ICD implantation and were followed for 24 ± 8 months, prospectively. A relevant SDB was defined as an apnea-hypopnea index of ≥10 events/hour. Of these 133 patients, 82 (62%) had SDB. Overweight (body mass index >29.1 vs 24.7 kg/m(2); p <0.001) was identified as the only independent risk factor for SDB. Appropriate ICD therapy intervention was significantly greater among patients with SDB than among patients without SDB (54% vs 34%, p = 0.03). Inappropriate ICD therapy intervention was documented more often in patients with SDB (n = 24 [29%] vs 7 [14%]; p = 0.04). An apnea-hypopnea index >10 events/hour was an independent predictor of appropriate ICD therapy on multivariate analysis (odds ratio 2.5, 95% confidence interval 1.8 to 4.04; p = 0.01). In conclusion, the present study is the first trial exploring the effect of SDB on the incidence of appropriate and inappropriate ICD therapy in patients with HF with a primary prevention indication. These results indicate that a preimplantation sleep study will identify patients with HF prone to receive appropriate and inappropriate ICD therapy.

Improved survival of patients with coronary artery disease and low ejection fraction with ICD implantation versus conventional therapy in a real world survey

Background

Coronary artery disease (CAD) is associated with an increased risk for sudden cardiac death. Randomized controlled trials have shown that implantable cardioverter defibrillators (ICD) improve life expectancy unless they are implanted within the first days after an acute myocardial infarction and guidelines recommend their use. We aimed to validate that these results also apply to patients of a typical community hospital in Germany.

Methods

This was a retrospective analysis of patients undergoing coronary angiography in the Lippe-Detmold Hospital between 2003 and 2006. They had to have significant CAD and an ejection fraction (EF) ≤ 35% and no acute myocardial infarction within 28 days of implantation and no history of ventricular fibrillation.

Results

213 patients were included; 70 of which received an ICD. Patients with an ICD implantation were younger (64.8 ± 9.9 vs. 67.9 ± 9.8 years; p = 0.034), had single vessel CAD more frequently (22.9 vs. 11.2%; p = 0.025) and a lower EF (26.7 ± 6.3 vs. 29.1 ± 4.6%; p = 0.006). Hospital readmissions were comparable between the ICD and the control group (68.6 vs. 72.0%; p = 0.602). ICD therapy was associated with a considerable survival benefit compared to conventional therapy (HR 0.52; 95%CI 0.29-0.93; p = 0.027) in a Cox-Proportional Hazards Regression analysis.

Conclusions

Appreciating the potential limitations of retrospective studies, we found that ICD use was associated with improved survival in patients with significant CAD and an EF <= 35% typical for a large tertiary hospital.

Ventricular Arrhythmias Among Implantable Cardioverter-Defibrillator Recipients for Primary Prevention

Background—

An implantable cardioverter-defibrillator (ICD) is the therapy of choice for primary prevention in patients with ischemia who are at risk for sudden cardiac death (SCD). One third of patients with significant coronary disease have chronic total coronary occlusion (CTO), which is associated with long-term mortality in patients with previous myocardial infarction. However, the impact of CTO on the occurrence of ventricular arrhythmias and long-term mortality in ICD recipients remains unknown.

Methods and Results—

All consecutive patients with coronary artery disease receiving ICD therapy for the prevention of SCD were included in the study. Among other characteristics, the existence of CTO was assessed. During follow-up, the occurrence of appropriate device delivery because of ventricular arrhythmias as well as mortality were noted. A total of 162 patients (mean age, 62±9 years; 93% men) with an ICD were included and followed for a median of 26 months (interquartile range, 12–42). At least 1 CTO was present in 71 (44%) patients. Appropriate device therapy was detected in 18% of the patients during the follow-up. The presence of CTO was associated with higher ventricular arrhythmia and mortality rates (log-rank test, <0.01). Multivariable analysis revealed that CTO was independently associated with appropriate ICD intervention (hazard ratio, 3.5; P =0.003).

Conclusions—

In patients with ischemic heart disease receiving ICDs for primary prevention of SCD, CTO is an independent predictor for the occurrence of ventricular arrhythmias and has an adverse impact on long-term mortality.

Genome-wide association of implantable cardioverter-defibrillator activation with life-threatening arrhythmias

Objectives

To identify genetic factors that would be predictive of individuals who require an implantable cardioverter-defibrillator (ICD), we conducted a genome-wide association study among individuals with an ICD who experienced a life-threatening arrhythmia (LTA; cases) vs. those who did not over at least a 3-year period (controls).

Background

Most individuals that receive implantable cardioverter-defibrillators never experience a life-threatening arrhythmia. Genetic factors may help identify who is most at risk.

Methods

Patients with an ICD and extended follow-up were recruited from 34 clinical sites with the goal of oversampling those who had experienced LTA, with a cumulative 607 cases and 297 controls included in the analysis. A total of 1,006 Caucasian patients were enrolled during a time period of 13 months. Arrhythmia status of 904 patients could be confirmed and their genomic data were included in the analysis. In this cohort, there were 704 males, 200 females, and the average age was 73.3 years. We genotyped DNA samples using the Illumina Human660 W Genotyping BeadChip and tested for association between genotype at common variants and the phenotype of having an LTA.

Results and Conclusions

We did not find any associations reaching genome-wide significance, with the strongest association at chromosome 13, rs11856574 at P = 5×10⁻⁶. Loci previously implicated in phenotypes such as QT interval (measure of the time between the start of the Q wave and the end of the T wave as measured by electrocardiogram) were not found to be significantly associated with having an LTA. Although powered to detect such associations, we did not find common genetic variants of large effect associated with having a LTA in those of European descent. This indicates that common gene variants cannot be used at this time to guide ICD risk-stratification.

Trial Registration

ClinicalTrials.gov NCT00664807

Prophylactic implantable cardioverter-defibrillator treatment in the elderly: therapy, adverse events, and survival gain

AIMS

In elderly patients, obscurity remains regarding the benefit of implantable cardioverter-defibrillator (ICD) treatment as primary prevention of sudden cardiac death. This study assesses implant rates, therapy, adverse events, and survival gain in the elderly primary prevention ICD patient.

METHODS AND RESULTS

A total of 1395 patients treated with an ICD for primary prevention of sudden cardiac death at the Leiden University Medical Center were included and allocated to three groups according to age. Endpoints consisted of appropriate shocks and survival gain, defined as the time following first appropriate ICD shock to death. Mean follow-up was 2.9 ± 2.1 years. Fifty-one per cent of the patients were <65 years, 35% were 65-74 years, and 14% were ≥75 years. Prior to the year 2000, no ICDs were implanted in patients ≥75 years; 29% of the ICDs were implanted in patients 65-74 years. After 2005, 53% of the ICD recipients were ≥65 years at the time of implant, including 16% aged ≥75 years (P = 0.03). Five-year cumulative incidence of appropriate shocks was 19% for patients <65 years, 23% for patients 65-74 years, and 13% for patients ≥75 years (P = 0.47). At 1-year following appropriate shock, cumulative incidence for death was 35% for patients ≥75 years as compared with 7% for patients <65 years (P < 0.01).

CONCLUSION

In routine clinical practice, the percentage of patients ≥75 years receiving an ICD for primary prevention is increasing. Despite experiencing comparable rates of appropriate ICD shocks, life prolongation by ICD is significantly less in elderly as compared to younger patients.

Graves' disease complicated by ventricular fibrillation in three men who were smokers

BACKGROUND

Thyrotoxicosis is known to be associated with sinus tachycardia and supraventricular tachyarrhythmias, but rarely with ventricular fibrillation (Vf), which has only occurred in some patients with hypokalemic periodic paralysis or ischemic heart disease.

PATIENT FINDINGS

We present three men who were transferred to our hospital with Graves' disease who developed idiopathic Vf. None of them had hypokalemic periodic paralysis or ischemic heart disease but all were smokers. None of other patients with thyrotoxicosis (587 females and 155 males) who were seen at our hospital, in the period during which the three men were seen, had idiopathic Vf. In our three men with thyrotoxicosis and idiopathic Vf, there was no identifiable underlying heart disease. One of the three patients died of hypoxic encephalopathy. The other two men did not have recurrent Vf after their thyroid function normalized.

SUMMARY

These cases and a review of similar cases in the literature imply that improving thyrotoxicosis seems to be effective for treating idiopathic Vf in some patients.

CONCLUSIONS

Our findings suggest that thyroid hormone excess might play a direct role in the development of Vf in susceptible individuals. Our experience with these three patients suggests that smoking men with thyrotoxicosis likely have an increased risk for Vf, even if they do not have other predisposing factors.

Use of implantable cardioverter-defibrillators

The implantable cardioverter-defibrillator (ICD) is the most effective treatment for patients with life-threatening ventricular tachycardia or ventricular fibrillation not due to reversible causes. The American College of Cardiology/American Heart Association class I and IIa indications for an ICD are discussed. Patients with ICDs who need pacing should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing, at a rate of 70/min. Patients with ICDs should be treated with β-blockers, statins and angiotensin-converting enzyme inhibitors or angiotensin receptor blockers.