Background: The highest rate of death is in the first few weeks after myocardial infarction (MI). However, the assessment of indications for primary prevention implantable cardioverter-defibrillator (ICD) implantation should be postponed until at least 40 days after MI.
Aims: Our aim was to identify the subgroup of high-risk patients with reduced left ventricular ejection fraction (LVEF) who would benefit from primary prevention ICD implantation within 40 days of MI.
Methods: Out of 205 606 patients with MI, in this study, we included 18 736 patients treated invasively, with LVEF <40%, who survived until hospital discharge. Patients were divided into two groups according to the survival status at 40 days - patients who died within this period (n = 1331) and patients who survived (n = 17405).
Results: Among all patients who died within 12-months after MI, 37.7% did die during the first 40 days. Patients with cardiac arrest before hospital admission or within the first 48 hours of hospitalization (hazard ratio [HR], 3.35; 95% confidence interval [CI], 2.82-3.98; P <0.0001], cardiogenic shock before admission or during hospitalization (HR, 3.06; 95% CI, 2.62-3.59; P <0.0001), unsuccessful percutaneous coronary interventions (PCI; HR, 2.42; 95% CI, 2.11-2.84; P <0.0001), LVEF <20% (ref. LVEF ≥30%; HR, 2.75; 95% CI, 2.25-3.36; P <0.0001) had approximately threefold and patients with chronic kidney disease almost 1.5-times (HR, 1.25; 95% CI, 1.47-3.59; P = 0.0053) higher 40-day mortality compared to patients without these risk factors. The most striking differences in mortality between these subgroups were observed shortly after discharge.
Conclusions: The highest risk of death in patients with reduced LVEF who survived until hospital discharge occurred within the first 40 days after MI. There is a possibility to select patients with the worst prognosis and treat them more aggressively.
Keywords: implantable cardioverter-defibrillator; myocardial infarction.