Clinical practice of defibrillator implantation after myocardial infarction: impact of implant time: results from the PreSCD II registry

Abstract

Aims: Current guidelines recommend implantable cardioverter-defibrillator (ICD) therapy for primary prevention of sudden cardiac death in patients with the reduced left ventricular function (LVEF ≤30%) not earlier than 40 days after myocardial infarction (MI). The aim of the prospective Prevention of Sudden Cardiac Death II (PreSCD II) registry was to investigate the clinical practice of ICD therapy in post-MI patients and to assess the impact on survival.

Methods and results: 10,612 consecutive patients (61 ± 12 years, 76% male) were enrolled 4 weeks or later after MI in 19 cardiac rehabilitation centres in Germany from December 2002 to May 2005. All patients with left ventricular ejection fraction (LVEF) ≤40% (n = 952) together with a randomly selected group of patients with preserved left ventricular function (n = 1106) were followed for 36 months. Cox proportional hazard models were used to correlate ICD implantation and survival with baseline characteristics. Of all patients studied, 75.9% were enrolled within 4-8 weeks, 10.7% more than 1 year after MI. Pre-specified Group 1 with an LVEF ≤30% consisted of 269 patients (2.5%), Group 2 with LVEF 31-40% of 727 patients (6.9%), and Group 3 with LVEF >40% of 1148 randomly selected patients from the cohort of 9616 patients with preserved LV function. After 36 months, only 142 patients (6.9%) had received an ICD; 82 (31.7%) of Group 1, 49 (7%) of Group 2, and 11 (1%) in Group 3. The ICD was implanted in 47% of all patients within 1 year after their index MI. Implantable cardioverter-defibrillator patients were predominantly characterized by low ejection fraction, but also by several other independent risk factors. Patients who received an ICD had an adjusted 44% lower mortality (hazard ratio 0.56, 95% confidence intervals 0.32-1.01; P = 0.053) than comparable patients without ICD therapy. All cause mortality of ICD recipients was significantly lower if the ICD was implanted later than 11 months after acute MI (P < 0.001).

Conclusions: The PreSCD II registry demonstrated that the number of patients who develop a low LVEF (≤30%) after acute MI is small. However, only few patients with guideline-based ICD indication received ICD therapy. All cause mortality was significantly reduced only if the ICD was implanted late (>11 months) after MI.

Figure 1

Flow chart of the PreSCD II registry.

Figure 2

Effect of various patient and treatment characteristics on the probability of ICD implantation during 36-month follow-up of 2058 patients (hazard ratios).

Figure 3

Kaplan–Meier estimate of all-cause mortality in the 36-months follow-up, divided by LVEF groups, restricted to recent myocardial infarctions (≤8 weeks at inclusion). The P-value results from a log-rank test.

Figure 4

Effect of various patient and treatment characteristics on mortality during 36-month follow-up of 2058 patients.