Proposed synergistic effect of calcium channel blockers with lipid-lowering therapy in retarding progression of coronary atherosclerosis.

Abstract

Lipid-lowering therapy now has undoubtedly proven to be an effective therapeutic modality to retard the progression of coronary atherosclerosis. An additional approach for prevention of the progression of atherosclerosis is calcium channel blocker (CCB) treatment. Evidence indicating that CCBs inhibit atherosclerosis is less unequivocal than the clear evidence for lipid-lowering therapy. Many investigations support the view that a number of key processes in atherosclerosis may be influenced by CCBs. From the "negative" and "positive" studies with CCBs performed in animals and humans we must conclude that apparently some, but not all, types or stages of the atherosclerotic process are inhibited by CCBs. To assess whether lipid-lowering therapy and CCB treatment may have an additive or synergistic beneficial effect on human atherosclerosis, which is conceivable because their anti-atherosclerotic properties differ, data from the angiographic lipid-lowering trial REGRESS (pravastatin vs. placebo) were reviewed. In REGRESS, patients in the pravastatin group had significantly less progression if cotreated with CCBs as compared with those with no CCB cotreatment, whereas in the placebo (no pravastatin) group no effect of CCB treatment was observed. With respect to angiographic new lesion formation, in the pravastatin group there were 50% less patients with new angiographic lesions if cotreated with CCBs as compared with no CCB cotreatment, whereas in the placebo (no pravastatin) group, again, no significant effect of CCB treatment was observed. No beneficial effects of CCB treatment on clinical events were observed during the 2-year study follow-up. In view of the correlation between angiographic progression and subsequent clinical events as demonstrated in several large trials, it is not unrealistic to also anticipate in this population, a beneficial effect on clinical events with longer follow-up. Although the REGRESS trial was not designed to evaluate combination therapy, the results suggest that addition of CCBs to HMG-CoA reductase inhibitor therapy (pravastatin) acts synergistically in retarding the progression of established coronary atherosclerosis. These results appear to warrant prospective randomized trials to determine in a more definitive manner the merits of this combination in the prevention of progression of coronary atherosclerosis. Currently a number of studies in these fields are being designed or are already underway.