Background: Short-acting calcium channel blockers (Ca-blockers) have been shown in some studies to increase the risk of myocardial infarction (MI) and post-MI complications. Data from large, international, randomised studies such as the INJECT trial may bring new important information on the effects of medication used before MI, on the course of MI and post-MI complications.
Aim: To assess the effects of beta-blocker and Ca-blocker therapy administered prior to MI on the early and late outcome after MI.
Methods: The study group consisted of 6001 patients with acute MI treated according to the INJECT protocol. The patients were divided into four groups according to the type of treatment before the index MI: Group I (n=580) - patients treated with beta-blockers; Group II (n=831) - patients treated with Ca-blockers; Group III (n=277) - patients treated with both beta-blockers and Ca-blockers; and Group IV (n=4313) - no beta-blocker or Ca-blocker treatment. The analysed end-points were 35- and 180-day mortality as well as angina recurrences, occurrence of heart failure, atrial fibrillation/flutter and asystole.
Results: During hospital stay, supraventricular arrhythmias, asystole, recurrent ischaemia and heart failure occurred more frequently in patients from groups II and III than in other groups. Early mortality was significantly higher in group II (p<0.001) and group III (p<0.002) than in group IV. Late mortality was the lowest in group IV, followed by group I. Cox proportional hazards multivariable analysis revealed that hypotension, Killip class IV (p<0.001), previous Ca-blocker (p<0.01) or Ca- and beta-blocker treatment (p<0.01) as well as previous MI (p<0.05) were the independent predictors of death.
Conclusions: Compared with beta-blocker therapy or no treatment, previous use of Ca-blockers increases both early and long-term complication rates in patients with MI.