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Exercise training and implantable cardioverter-defibrillator shocks in patients with heart failure: results from HF-ACTION (Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing).

ABSTRACT: The purpose of this study was to determine whether exercise training is associated with an increased risk of implantable cardioverter-defibrillator (ICD) therapy in patients with heart failure (HF).Few data are available regarding the safety of exercise training in patients with ICDs and HF.HF-ACTION (Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing) randomized 2,331 outpatients with HF and an ejection fraction (EF) ≤35% to exercise training or usual care. Cox proportional hazards modeling was used to examine the relationship between exercise training and ICD shocks.We identified 1,053 patients (45%) with an ICD at baseline who were randomized to exercise training (n = 546) or usual care (n = 507). Median age was 61 years old, and median EF was 24%. Over a median of 2.2 years of follow-up, 20% (n = 108) of the exercise patients had a shock versus 22% (n = 113) of the control patients. A history of sustained ventricular tachycardia/fibrillation (hazard ratio [HR]: 1.93 [95% confidence interval (CI): 1.47 to 2.54]), previous atrial fibrillation/flutter (HR: 1.63 [95% CI: 1.22 to 2.18]), exercise-induced dysrhythmia (HR: 1.67 [95% CI: 1.23 to 2.26]), lower diastolic blood pressure (HR for 5-mm Hg decrease <60: 1.35 [95% CI: 1.12 to 1.61]), and nonwhite race (HR: 1.50 [95% CI: 1.13 to 2.00]) were associated with an increased risk of ICD shocks. Exercise training was not associated with the occurrence of ICD shocks (HR: 0.90 [95% CI: 0.69 to 1.18], p = 0.45). The presence of an ICD was not associated with the primary efficacy composite endpoint of death or hospitalization (HR: 0.99 [95% CI: 0.86 to 1.14], p = 0.90).We found no evidence of increased ICD shocks in patients with HF and reduced left ventricular function who underwent exercise training. Exercise therapy should not be prohibited in ICD recipients with HF. (Exercise Training Program to Improve Clinical Outcomes in Individuals With Congestive Heart Failure; NCT00047437)

SUBMITTER: Piccini JP

PROVIDER: S-EPMC3735226 | biostudies-other | 2013 Apr

REPOSITORIES: biostudies-other

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Project description:BackgroundThere are conflicting data on the impact of implantable cardioverter-defibrillator (ICD) shocks on subsequent mortality.ObjectivesThe aim of this study was to determine whether the arrhythmic substrate leading to ICD therapy or the therapy itself increases mortality.MethodsThe study cohort included 5,516 ICD recipients who were enrolled in 5 landmark ICD trials (MADIT-II, MADIT-RISK, MADIT-CRT, MADIT-RIT, RAID). The authors evaluated the association of device therapy with subsequent mortality in 4 separate time-dependent models: model I, type of ICD therapy; model II, type of arrhythmia for which ICD therapy was delivered; model III, combined assessment of all arrhythmia and therapy types during follow-up; and model IV, incremental risk associated with repeated ICD shocks.ResultsWhen analyzed by the type of ICD therapy (model I), a first appropriate ICD shock was associated with increased risk of subsequent mortality with or without concomitant occurrence of inappropriate shock during follow-up (hazard ratio [HR]: 2.78 and 2.31; p < 0.001 and p = 0.12), whereas inappropriate shock alone was not associated with mortality risk (HR: 1.23; p = 0.42). Similarly, ICD therapy for ventricular tachycardia (VT) ≥200 beats/min or ventricular fibrillation (VF) (model II) was associated with increased risk of death with or without concomitant therapy for VT <200 beats/min (HRs: 2.25 and 2.62; both p < 0.001), whereas appropriate therapy for VT <200 beats/min or inappropriate therapy (regardless of etiology) did not reach statistical significance (all p > 0.10). Combined assessment of all therapy and arrhythmia types during follow-up (model III) showed that appropriate ICD shocks for VF, shocks for fast VT (≥200 beats/min) without prior antitachycardia pacing (ATP), as well as shocks for fast VT delivered after failed ATP, were associated with the highest risk of subsequent death (HR: all >2.8; p < 0.001). Finally, 2 or more ICD appropriate shocks were not associated with incremental risk to the first appropriate ICD shock (model IV).ConclusionThe combined data from 5 landmark ICD trials suggest that the underlying arrhythmic substrate rather than the ICD therapy is the more important determinant of mortality in ICD recipients.

Project description:BackgroundAppropriate shock therapy is associated with subsequent all-cause death in heart failure (HF) patients who receive an implantable cardioverter defibrillator (ICD) for the primary prevention of sudden cardiac death. To evaluate the impact of signal-averaged electrocardiography (SAECG) findings on appropriate shocks in prophylactic ICD patients with nonischemic systolic HF.MethodsWe studied 86 patients with nonischemic HF and a left ventricular ejection fraction ≤ 35% who underwent new ICD implantation for the primary prevention of sudden cardiac death. We excluded patients who had a previously implanted permanent pacemaker and patients who received cardiac resynchronization therapy with an ICD. SAECG was performed before implantation. Abnormal SAECG findings were defined if 2 of the following 3 conditions were identified: filtered QRS duration (fQRS) ≥ 114 ms, root-mean-square voltage during the last 40 ms of the fQRS (RMS 40) < 20 μV, and duration of the low-amplitude potentials < 40 μV (LAS 40) > 38 ms; additionally, patients with a QRS complex ≥ 120 ms who met both the RMS 40 and LAS 40 criteria were also considered to have abnormal SAECG findings. The primary outcome was the first occurrence of appropriate shock after implantation of the ICD. The secondary outcomes were the first occurrence of inappropriate shock and all-cause mortality.ResultsForty-two patients met the criteria for abnormal SAECG findings (49%). During a median follow-up period of 61 months, 17 patients (20%) died, 24 (28%) received appropriate shock therapy, and 19 (22%) received inappropriate shock therapy. There was a significantly higher incidence of appropriate shocks in patients with abnormal SAECG findings than in those with normal SAECG findings (log-rank test, p = 0.025). Multivariate analysis revealed that abnormal SAECG findings were independently associated with the occurrence of appropriate shock (hazard ratio 2.67, 95% confidential interval 1.14-6.26). However, abnormal SAECG findings were not related to inappropriate shock. There was no difference in the incidence of all-cause death between patients with abnormal and normal SAECG findings.ConclusionsOur results suggest that abnormal SAECG findings are associated with a high probability of appropriate shocks in prophylactic ICD patients with nonischemic systolic HF.

Project description:ObjectivesThis study sought to test specialized processing of laser Doppler signals for discriminating ventricular fibrillation (VF) from common causes of inappropriate therapies.BackgroundInappropriate implantable cardioverter-defibrillator (ICD) therapies remain a clinically important problem associated with morbidity and mortality. Tissue perfusion biomarkers, implemented to assist automated diagnosis of VF, sometimes mistake artifacts and random noise for perfusion, which could lead to shocks being inappropriately withheld.MethodsThe study tested a novel processing algorithm that combines electrogram data and laser Doppler perfusion monitoring as a method for assessing circulatory status. Fifty patients undergoing VF induction during ICD implantation were recruited. Noninvasive laser Doppler and continuous electrograms were recorded during both sinus rhythm and VF. Two additional scenarios that might have led to inappropriate shocks were simulated for each patient: ventricular lead fracture and T-wave oversensing. The laser Doppler was analyzed using 3 methods for reducing noise: 1) running mean; 2) oscillatory height; and 3) a novel quantification of electromechanical coupling which gates laser Doppler relative to electrograms. In addition, the algorithm was tested during exercise-induced sinus tachycardia.ResultsOnly the electromechanical coupling algorithm found a clear perfusion cut off between sinus rhythm and VF (sensitivity and specificity of 100%). Sensitivity and specificity remained at 100% during simulated lead fracture and electrogram oversensing. (Area under the curve running mean: 0.91; oscillatory height: 0.86; electromechanical coupling: 1.00). Sinus tachycardia did not cause false positive results.ConclusionsQuantifying the coupling between electrical and perfusion signals increases reliability of discrimination between VF and artifacts that ICDs may interpret as VF. Incorporating such methods into future ICDs may safely permit reductions of inappropriate shocks.

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Exercise training and implantable cardioverter-defibrillator shocks in patients with heart failure: results from HF-ACTION (Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing).

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