In total, 66 reports of studies were identified and extracted, although some were multiple publications of the same clinical trial; only a limited number of the studies were reported in detail and included in the statistical analyses. Seven RCTs (n=4,516) involving patients with MI, and 3 RCTs (n=1,020) involving patients with angina, were included in the analyses. None of the 17 identified RCTs involving patients with hypertension were analysed or reported in detail, due to their limited treatment duration and size.
The relative risks and 95% CIs were presented diagrammatically; the absolute values were not reported.
Acute MI (7 of the 7 studies analysed).
The combined relative risks (three combinations of the 7 studies) for nonfatal reinfarction ranged from 0.79 to 0.80 in favour of verapamil. This corresponded to a 20 to 21% risk reduction for nonfatal reinfarction associated with verapamil. The effect on mortality associated with verapamil ranged from a 5.6% increase to an 18.5% reduction in mortality. The combined odds reduction (using three different combinations of the 7 studies) ranged from 7 to 14% in favour of verapamil. There was no evidence of marked between-study differences in the relative risk (p=0.50). The combined relative risk (5 studies) of a combined adverse outcome (death or reinfarction) in patients taking verapamil, compared with controls, was estimated to be 0.82 (95% CI: 0.70, 0.97).
Angina (3 of the 43 studies analysed).
Forty of the 43 studies identified were short-term crossover studies with a treatment duration of less than 4 weeks; these studies were not included in the analysis (no further details provided). The remaining 3 studies were double-blind parallel group studies (2 placebo and 1 versus metoprolol), which were discussed in detail. The paucity of the data from the 3 trials was such that no results were reported for the formal pooled analysis. Examining the 3 studies individually, no significant associations with verapamil were identified with respect to the incidence of nonf.:
No deaths or nonfatal infarctions were observed in the 17 trials (12 short-term crossover trials; 5 parallel, randomised double-blind studies). However, the studies were described as uninformative by the authors as they were limited in both treatment duration and size (no further details provided).