The Significance of Shocks in Implantable Cardioverter Defibrillator Recipients

Large-scale implantable cardioverter defibrillator (ICD) trials have unequivocally shown a reduction in mortality in appropriately selected patients with heart failure and depressed left ventricular function. However, there is a strong association between shocks and increased mortality in ICD recipients. It is unclear if shocks are merely a marker of a more severe cardiovascular disease or directly contribute to the increase in mortality. The aim of this review is to examine the relationship between ICD shocks and mortality, and explore possible mechanisms. Data examining the effect of shocks in the absence of spontaneous arrhythmias as well as studies of non-shock therapy and strategies to reduce shocks are analysed to try and disentangle the shocks versus substrate debate.

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Abstract 2037: Renal Dysfunction and Appropriate Shock Therapy in Implantable Cardioverter Defibrillator Patients with Nonischemic Heart Failure

Circulation ◽

10.1161/circ.116.suppl_16.ii_441-a ◽

2007 ◽

Vol 116 (suppl_16) ◽

Author(s):

Atsushi Takahashi ◽

Tsuyoshi Shiga ◽

Keisuke Futagawa ◽

Ryusuke Kimura ◽

Koichiro Ejima ◽

...

Keyword(s):

Heart Failure ◽

Renal Insufficiency ◽

Renal Dysfunction ◽

Implantable Cardioverter Defibrillator ◽

Shock Therapy ◽

Left Ventricular ◽

Left Ventricular Ejection ◽

Icd Implantation ◽

Cardioverter Defibrillator ◽

Icd Shock

Background: Implantable Cardioverter Defibrillator (ICD) prevent sudden cardiac death in high risk patients with heart failure. The presence of coexisting conditions has a substantial effect on the rate of arrhythmic events in heart failure patients. Renal dysfunction is associated with mortality in patients with myocardial infarction or heart failure, but the influence of degrees of renal impairment is less well defined. Methods: A total of 221 patients who underwent ICD implantation were included between 1990 and 2006. Gromerular Filteration Rate (GFR) was estimated using the Modification of Diet in Renal Disease (MDRD) and renal insufficiency was defined as MDRD GFR<60mL/min/1.73m 2 . Differences in arrhythmia recurrences according to the MDRD GFR were compared by Kaplan-Meier survival curves. Results: During a mean follow-up time of 3.7±2.8 years, 82 (37%) of 221 patients (mean age; 4.7±1.3 years, 71% male) experienced appropriate ICD shock therapy. There was a trend of higher cumulative rate of appropriate ICD shock therapies in patients with renal insufficiency than other patients (p<0.10). The result of subgroup analysis of 94 patients with low LVEF (LVEF<35%) indicated that the patients with renal insufficiency experienced electrical storms more frequently (p<0.05). After correcting for age, sex, left ventricular ejection fraction (LVEF), indication for ICD implantation, and use of beta-blockers in a Cox regression model, low MDRD GFR was still an independent predictor of the time to first appropriate ICD shock (hazard ratio [HR] 2.30, 95% confidence interval [CI] 1.13–4.69, p<0.05). Below 60mL/min/1.73m 2 , each reduction of the MDRD GFR by 10 units was associated with a HR for appropriate shock of 1.40 (95% CI, 1.00 to 1.95). Conclusion: Renal insufficiency is associated with increased rate of arrhythmic event in nonischemic HF patients. Especially, those patients with low LVEF and renal dysfunction experience more frequent ICD shocks.

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Implantable Cardioverter-Defibrillator Efficacy in Patients With Heart Failure and Left Ventricular Dysfunction (from the MADIT II Population)

The American Journal of Cardiology ◽

10.1016/j.amjcard.2005.02.021 ◽

2005 ◽

Vol 95 (12) ◽

pp. 1487-1491 ◽

Cited By ~ 41

Author(s):

Wojciech Zareba ◽

Katarzyna Piotrowicz ◽

Scott McNitt ◽

Arthur J. Moss

Keyword(s):

Heart Failure ◽

Implantable Cardioverter Defibrillator ◽

Left Ventricular Dysfunction ◽

Ventricular Dysfunction ◽

Left Ventricular ◽

Cardioverter Defibrillator ◽

Patients With Heart Failure ◽

Madit Ii

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Insurance Type Is Associated with Rate of Implantable Cardioverter Defibrillator Implantation and One-Year Mortality of Patients with Heart Failure (A New Jersey Statewide Study)

Journal of Cardiac Failure ◽

10.1016/j.cardfail.2009.06.082 ◽

2009 ◽

Vol 15 (6) ◽

pp. S90

Author(s):

William J. Kostis ◽

Yingzi Deng ◽

Abel E. Moreyra ◽

John B. Kostis

Keyword(s):

Heart Failure ◽

New Jersey ◽

Implantable Cardioverter Defibrillator ◽

Cardioverter Defibrillator ◽

Implantable Cardioverter Defibrillator Implantation ◽

Insurance Type ◽

Patients With Heart Failure ◽

One Year

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The Timing of Implantable Cardioverter-Defibrillator Implantation in Patients with Heart Failure

Current Cardiology Reports ◽

10.1007/s11886-012-0262-1 ◽

2012 ◽

Vol 14 (3) ◽

pp. 299-307 ◽

Cited By ~ 1

Author(s):

Nawaf S. Al-Majed ◽

Justin A. Ezekowitz

Keyword(s):

Heart Failure ◽

Implantable Cardioverter Defibrillator ◽

Cardioverter Defibrillator ◽

Implantable Cardioverter Defibrillator Implantation ◽

Patients With Heart Failure

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Abstract 5700: Worsening Renal Function and Arrhythmic Event in Implantable Cardioverter Defibrillator Patients with Nonischemic Heart Failure

Circulation ◽

10.1161/circ.118.suppl_18.s_988 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Atsushi Takahashi ◽

Tsuyoshi Shiga ◽

Daigo Yagishita ◽

Keisuke Futagawa ◽

Naoki Serizawa ◽

...

Keyword(s):

Heart Failure ◽

Renal Function ◽

Renal Dysfunction ◽

Implantable Cardioverter Defibrillator ◽

Shock Therapy ◽

Electrical Storm ◽

Icd Implantation ◽

Cardioverter Defibrillator ◽

Arrhythmic Event ◽

Icd Shock

Purpose: Implantable Cardioverter Defibrillator (ICD) prevents sudden cardiac death in high risk patients with heart failure (HF). Worsening renal function (WRF) is associated with mortality in patients with myocardial infarction or HF, but its effect on lethal arrhythmia is unknown. We evaluated the influence of WRF on the occurrence of arrhythmic events in patients with nonischemic HF and ICD. Methods: A total of 286 nonischemic HF patients who underwent ICD implantation between 1990 and 2007 were studied. Estimated Glomerular Filtration Rate (eGFR) was calculated using the Modification of Diet in Renal Disease. Renal dysfunction was defined as eGFR <60mL/min/1.73m 2 and WRF was defined as 15mL/min/1.73m 2 per year. Differences in arrhythmia recurrences according to the eGFR and WRF were compared by Kaplan-Meier survival curves. Results: During a mean follow-up time of 2.2+/−1.0 years, 94 (33%) of 286 patients (mean age; 57+/−15 years, 72% male) experienced appropriate ICD shock therapy. There was a significantly higher cumulative rate of appropriate ICD shock therapy (p<0.05) and electrical storm (p<0.05) in patients with renal dysfunction than others. The patients with renal dysfunction at baseline experience WRF more frequently than other patients (53% vs. 23%, respectively, p<0.01). After correcting for age, sex, left ventricular ejection fraction (LVEF), indication for ICD implantation, and use of beta-blockers in a Cox regression model, WRF was still an independent predictor of the time to first appropriate shock (HR 2.21, 95% CI 1.32–3.69, p<0.05) and electrical storm (HR 2.22, 95% CI 1.19 – 4.13, p<0.05). The result of subgroup analysis of 147 patients with low LVEF (LVEF<35%) indicated that the patients with WRF experienced electrical storms more frequently (p<0.05). Conclusion: WRF is associated with increased rate of arrhythmic event in nonischemic HF patients. Especially, those patients with low LVEF and WRF experience more frequent ICD shocks.

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