The effect of nifedipine GITS on outcomes in patients with previous myocardial infarction: A subgroup analysis of the INSIGHT study

Post-myocardial infarction (MI) patients have a higher risk for subsequent cardiovascular and cerebrovascular events than the average population. This study was to test the effects on outcomes of nifedipine GITS compared to the diuretic combination co-amilozide in hypertensive patients with a history of MI on outcomes (subset of the INSIGHT study). The multinational, randomised, double-blind International Nifedipine GITS Study: Intervention as a Goal in Hypertension Treatment (INSIGHT) study compared the treatment effects of nifedipine GITS 30 mg and co-amilozide (hydrochlorothiazide 25 mg plus amiloride 2.5 mg) in hypertensive patients aged 55-80 years with a blood pressure of 150/95 mmHg (or 160 mmHg systolic). This pre-specified subanalysis was performed in patients with a history of MI. The primary outcome was a composite of cardiovascular death, non-fatal stroke, MI, and heart failure. Of 6,321 randomised patients, 383 (6.1%) had a previous MI. The percentage of primary outcomes in post-MI patients did not differ between the two treatment groups (14.9%). The number of post-MI patients with composite secondary outcomes was 53 (27.2%) in the nifedipine GITS group and 60 (31.9%) in the co-amilozide group. The incidence rates of primary and secondary outcomes were higher in patients with a previous MI than in patients without a history of MI. For the randomised use of nifedipine GITS and co-amilozide in hypertensive patients with a previous MI, the choice seemed unimportant for outcomes and blood pressure lowering. The results of this subgroup analysis are consistent with INSIGHT's overall findings of no significant differences in efficacy, suggesting that post-MI hypertensive patients are no more likely to suffer further events when treated with long-acting nifedipine than on co-amilozide.