Prediction of Appropriate Shocks Using 24-Hour Holter Variables and T-Wave Alternans After First Implantable Cardioverter-Defibrillator Implantation in Patients With Ischemic or Nonischemic Cardiomyopathy.

In patients treated with implantable cardioverter defibrillator (ICD), prediction of both overall survival and occurrence of shocks is important if improved patient selection is desired. We prospectively studied the predictive value of biomarkers and indexes of cardiac and renal function and spectral microvolt T-wave alternans testing and 24-hour Holter variables in a population who underwent first ICD implantation. Consecutive patients in sinus rhythm with ischemic or dilated cardiomyopathy scheduled for primary or secondary prophylactic ICD implantation were enrolled. Exercise microvolt T-wave alternans and 24-hour Holter for number of ventricular premature contractions (VPCs), deceleration capacity, heart rate variability, and heart rate turbulence were done. Death of any cause and first appropriate ICD shock were defined as end points. Over 33 ± 15 months of follow-up, 36 of 253 patients (14%) received appropriate shocks and 39 of 253 patients (15%) died. Only 3 of 253 patients (1%) died after receiving at least 1 appropriate shock. In univariate analyses, New York Heart Association class, ejection fraction, N-terminal pro brain-type natriuretic peptide (NT-proBNP), renal function, ICD indication, deceleration capacity, heart rate variability, and heart rate turbulence were predictive of all-cause mortality and VPC number and deceleration capacity predicted first appropriate shock. NT-proBNP (≥1,600 pg/ml) was identified as the only independent predictor of all-cause mortality (hazard ratio 3.0, confidence interval 1.3 to 7.3, p = 0.014). In contrast, VPC number predicted appropriate shocks (hazard ratio 2.3, confidence interval 1.0 to 5.5, p = 0.047) as the only independent risk marker. In conclusion, NT-proBNP is a strong independent predictor of mortality in a typical prospective cohort of newly implanted patients with ICD, among many electrocardiographic and clinical variables studied. Number of VPCs was identified as a predictor of appropriate shocks (clinicaltrials.gov: NCT02010515).

Longevity of implantable cardioverter-defibrillators in a single-center population.

BACKGROUND OR PURPOSE: Real-life comparative data of implantable cardioverter-defibrillator (ICD) longevity are needed to identify the best possible device longevity for optimal patient comfort and to minimize risk for multiple replacements. METHODS: We retrospectively studied ICD longevity in a large single-center population. At our institution, 1272 consecutive patients were implanted with 1665 ICD or cardiac resynchronization therapy with defibrillator (CRT-D) devices between 1998 and 2010. Device data and follow-up were retrieved from the continuous ICD clinic documentation, and generator replacements were verified from the hospital charts. Kaplan-Meier event probabilities for the time to generator replacement were calculated according to device type, pacing percentage (sum of atrial, right and left ventricular pacing, if applicable) and right ventricular pacing threshold, incidence of ICD shocks, and manufacturer. Multivariate Cox proportional hazards regression was performed in addition. RESULTS: A total of 470 devices were replaced for elective replacement indicator. These occurred after 5.4 years (95% confidence interval, 5.1 to 5.6 years) in 175 of 625 implanted Boston Scientific or Guidant devices, after 5.7 years (5.5 to 5.9 years) in 266 of 883 Medtronic devices, and 5.2 years (5.0 to 5.4 years) in 29 of 157 Biotronik devices, respectively. Differences between manufacturers remained significant upon multivariate analysis (Medtronic vs. Boston Scientific: P = 0.01; both vs. Biotronik: P < 0.01) as did differences of device type (single- and dual-chamber ICD vs. CRT-D, P < 0.01) and pacing percentage (P < 0.01). Pacing output and ICD shocks did not influence battery longevity. CONCLUSION: ICD longevity differed significantly between manufacturers, independent of device type or pacing parameters.