Background: For allocation of primary ICD-therapy, a possible lower limit of inclusion criteria--defining overly advanced heart failure--is less well investigated. Also, a multi-variable approach to stratification beyond ejection fraction (LVEF) appears warranted. We examined whether adding a selection limit of peak VO(2) <or= 14 ml/kg/min to LVEF <or= 20% improves stratification. Furthermore, we sought to provide current survival data and a size-estimate for prospective trials based on real-life data for this high risk cohort.
Methods: In our prospective clinical registry 1,926 patients with systolic CHF were recruited consecutively since 1994. Of these patients, 292 met the selection criteria described above. The mean age was 57.6 +/- 9.5 years, 83% were male, 37% had ischemic cardiomyopathy and 28% received primary ICD-therapy. All cause mortality was considered as end point.
Results: Median follow-up was 45 (18-86) months. ICD was not a significant predictor of outcome either for the entire population, or grouped according to aetiology of CHF. Still, 3-year mortality was 15% (ICD-patients) Vs. 28% (non-ICD-patients); P = 0.05; under combination medical therapy. Inversely, in ICD-patients medical combination therapy conveyed a significant survival benefit (P < 0.001). Consequently, the number-needed-to-treat was eight under combination therapy and the size estimate amounts to 300 patients for a prospective trial in this cohort.
Conclusion: A cut-off of LVEF <or= 20% and pVO(2) <or= 14 ml/kg/min could identify patients that do not draw a significant survival benefit from adjunct primary ICD-therapy. Our results indicate the need for a specific randomized trial in this cohort. The according mortality data and a size estimate are provided.