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BACKGROUND Implantable cardioverter-defibrillators (ICDs) are underutilized in Asia, Latin America, Eastern Europe, the Middle East, and Africa. The Improve SCA Study is the largest prospective study to evaluate the benefit of ICD therapy in underrepresented geographies. This analysis reports the primary objective of the study. OBJECTIVES The objectives of this study was to determine whether patients with primary prevention (PP) indications with specific risk factors (1.5PP: syncope, nonsustained ventricular tachycardia, premature ventricular contractions .10/h, and low ventricular ejection fraction ,25%) are at a similar risk of life-threatening arrhythmias as patients with secondary prevention (SP) indications and to evaluate all-cause mortality rates in 1.5PP patients with and without devices. METHODS A total of 3889 patients were included in the analysis to evaluate ventricular tachycardia or fibrillation therapy and mortality rates. Patients were stratified as SP (n 5 1193) and patients with PP indications. The PP cohort was divided into 1.5PP patients (n 5 1913) and those without any 1.5PP criteria (n 5 783). The decision to undergo ICD implantation was left to the patient and/ or physician. The Cox proportional hazards model was used to compute hazard ratios. RESULTS Patients had predominantly nonischemic cardiomyopathy. The rate of ventricular tachycardia or fibrillation in 1.5PP patients was not equivalent (within 30%) to that in patients with SP indications (hazard ratio 0.47; 95% confidence interval 0.38-0.57) but was higher than that in PP patients without any 1.5PP criteria (hazard ratio 0.67; 95% confidence interval 0.46-0.97) (P 5 .03). There was a 49% relative risk reduction in all-cause mortality in ICD implanted 1.5PP patients. In addition, the number needed to treat to save 1 life over 3 years was 10.0 in the 1.5PP cohort vs 40.0 in PP patients without any 1.5PP criteria. CONCLUSION These data corroborate the mortality benefit of ICD therapy and support extension to a selected PP population from underrepresented geographies.

AimsThis study aims to demonstrate that primary prevention (PP) patients with one or more additional risk factors are at a similar risk of life-threatening ventricular arrhythmias when compared with secondary prevention (SP) patients, and would receive similar benefit from an implantable cardioverter defibrillator (ICD), or cardiac resynchronization therapy-defibrillator (CRT-D) implant. The study evaluates the benefits of therapy for high-risk patients in countries where defibrillation therapy for PP of SCA is underutilized.MethodsEnrolment will consist of 4800 ICD-eligible patients from Asia, Latin America, Eastern Europe, the Middle East, and Africa. Upon enrolment, patients will be categorized as SP or PP. Primary prevention patients will be assessed for additional risk factors: syncope/pre-syncope, non-sustained ventricular tachycardia, frequent premature ventricular contractions, and low left ventricular ejection fraction. Those PP patients with one or more risk factors will be categorized as ‘1.5’ patients. Implant of an ICD/CRT-D will be left to the patient and/or physician's discretion. The primary endpoint will compare the appropriate ICD therapy rate between SP and 1.5 patients. The secondary endpoint compares mortality between 1.5 implanted and non-implanted patients.ConclusionThe Improve SCA study will investigate a subset of PP patients, believed to be at similar risk of life-threatening ventricular arrhythmias as SP patients. Results may help clinicians identify and refer the highest risk PP patients for ICDs, help local societies expand guidelines to include PP of SCA utilizing ICDs, and provide additional geographical-relevant evidence to allow patients to make an informed decision whether to receive an ICD.Trial registrationNCT02099721.

Background: Despite available evidence that implantable cardioverter defibrillators (ICDs) reduce all-cause mortality among patients at risk for sudden cardiac death, utilization of ICDs is low especially in developing countries.Objective: To summarize reasons for ICD or cardiac resynchronization therapy defibrillator implant refusal by patients at risk for sudden cardiac arrest (Improve SCA) in developing countries.Methods: Primary prevention (PP) and secondary prevention (SP) patients from countries where ICD use is low were enrolled. PP patients with additional risk factors (syncope, ejection fraction < 25%, nonsustained ventricular tachycardia [NSVT], or frequent premature ventricular complexes) were further categorized as "1.5 PP patients." Candidates who declined implantation were asked for reasons for refusal. Baseline factors that may have influenced the implant decision were examined using logistic regression.Results: Among 3892 patients, the implant refusal rate was 46.5% among PP patients (n = 2700), and 10.3% among SP patients (n = 1192). The most common refusal reason was inability to pay for the device (53.8%), followed by not believing in the benefits of the ICD (19.4%). Among PP ICD candidates, those with no syncope, no NSVT, no premature ventricular contractions, shorter QRS duration, no atrial arrhythmias, and no left bundle branch block were more likely to refuse implant.Among SP candidates, a history of cardiovascular surgery and no sinus node dysfunction were significant predictors of ICD refusal. Additionally, countries had significant differences in patient refusal rates among PP and SP groups.Conclusion: Implant refusal among PP patients is high in many countries. Increased reimbursement and better awareness of the benefits of an ICD could increase their utilization. K E Y W O R D Simplantable cardioverter defibrillator, primary prevention, secondary prevention, sudden cardiac arrest, underutilizationThis is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Background: In primary prevention (PP) patients the utilization of implantable cardioverter-defibrillators (ICD) and cardiac resynchronization therapydefibrillators (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-Dindicated 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 [