Cardioverter-defibrillator reduces mortality risk in eligible ischemic and non-ischemic cardiomyopathy patients: Sub-analysis of the multi-center Improve SCA study

BACKGROUND & OBJECTIVE

Despite the burden of sudden cardiac arrest (SCA) worldwide, implantable cardioverter-defibrillators (ICDs) are underutilized, particularly in Asia, Latin America, Eastern Europe, the Middle East, and Africa. The Improve SCA trial demonstrated that primary prevention (PP) patients in these regions benefit from an ICD or a cardiac resynchronization therapy defibrillator (CRT-D). We aimed to compare the rate of device therapy and mortality among ischemic and non-ischemic cardiomyopathy (ICM and NICM) PP patients who met guideline indications for ICD therapy and had an ICD/CRT-D implanted.

METHODS

Improve SCA was a prospective, non-randomized, non-blinded multicenter trial that enrolled patients from the above-mentioned regions. All-cause mortality and device therapy were examined by cardiomyopathy (ICM vs NICM) and implantation status. Cox proportional hazards methods were used, adjusting for factors affecting mortality risk.

RESULTS

Of 1848 PP NICM patients, 1007 (54.5%) received ICD/CRT-D, while 303 of 581 (52.1%) PP ICM patients received an ICD/CRT-D. The all-cause mortality rate at 3 years for NICM patients with and without an ICD/CRT-D was 13.1% and 18.3%, respectively (HR 0.51, 95% CI 0.38-0.68, p < 0.001). Similarly, all-cause mortality at 3 years in ICM patients was 13.8% in those with a device and 19.9% in those without an ICD/CRT-D (HR 0.54, 95% CI 0.33-.0.88, p = 0.011). The time to first device therapy, time to first shock, and time to first antitachycardia pacing (ATP) therapy were not significantly different between groups (p ≥ 0.263).

CONCLUSIONS

In this large data set of patients with a guideline-based PP ICD indication, defibrillator device implantation conferred a significant mortality benefit in both NICM and ICM patients. The rate of appropriate device therapy was also similar in both groups.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT02099721.

The mortality analysis of primary prevention patients receiving a cardiac resynchronization defibrillator (CRT-D) or implantable cardioverter-defibrillator (ICD) according to guideline indications in the improve SCA study

BACKGROUND

In primary prevention (PP) patients the utilization of implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapy-defibrillators (CRT-D) remains low in many geographies, despite the proven mortality benefit.

PURPOSE

The objective of this analysis was to examine the mortality benefit in PP patients by guideline-indicated device type: ICD and CRT-D.

METHODS

Improve sudden cardiac arrest was a prospective, nonrandomized, nonblinded multicenter trial that enrolled patients from regions where ICD utilization is low. PP patient's CRT-D or ICD eligibility was based upon the 2008 ACC/AHA/HRS and 2006 ESC guidelines. Mortality was assessed according to guideline-indicated device type comparing implanted and nonimplanted patients. Cox proportional hazards methods were used, adjusting for known factors affecting mortality risk.

RESULTS

Among 2618 PP patients followed for a mean of 20.8 ± 10.8 months, 1073 were indicated for a CRT-D, and 1545 were indicated for an ICD. PP CRT-D-indicated patients who received CRT-D therapy had a 58% risk reduction in mortality compared with those without implant (adjusted hazard ratio [HR]: 0.42, 95% confidence interval [CI]: 0.28-0.61, p < .0001). PP patients with an ICD indication had a 43% risk reduction in mortality with an ICD implant compared with no implant (adjusted HR: 0.57, 95% CI: 0.41-0.81, p = .002).

CONCLUSIONS

This analysis confirms the mortality benefit of adherence to guideline-indicated implantable defibrillation therapy for PP patients in geographies where ICD therapy was underutilized. These results affirm that medical practice should follow clinical guidelines when choosing therapy for PP patients who meet the respective defibrillator device implant indication.