The impact of the calcium antagonist nifedipine on the angiographic progression of coronary artery disease: results of the INTACT (international nifedipine trial on antiatherosclerotic therapy)

INTACT is a study on the progression of coronary artery disease based on quantitated coronary angiography, applying the CAAS-system to assess the diameters of segments and stenoses and their changes over time. 348 of 425 patients (82%) underwent 2 angiograms after 3 years (175 on placebo, 173 on nifedipine, 80 mg per day). The analysis followed the intention to treat principle, as 66 patients stopped the trial medication for the last 12-18 months. Progression was defined either as an increase in the degree of stenosis by ≥20% or transition to occlusion, or as development of new stenoses (narrowings ≥20%) or new occlusions in coronary segments or sections previously angiographically normal. New lesions were selected both visually and by computer assessment. After 3 years no differences were found between groups with regard to pro- and regression of existing stenoses; however, there were fewer new lesions on nifedipine (144 on placebo versus 103 on nifedipine, -28%, p = 0.034) and also a trend to fewer patients with new lesions on nifedipine (-17%, n.s.). Hence, the calcium-antagonist significantly reduced the appearance of new stenoses and occlusions. There were interesting insights into the progression of CAD in general. Only 11.3% of existing stenoses showed progression and even fewer (4.3%) regression over 3 years, only few stenoses went into occlusion (2% of existing and 7.7% of new stenoses) (p = 0.000). Altogether, 56% of patients showed progression, 30.5% only in new stenoses, 11.8% only in old ones, and 14.1% in both. Hence, the strongest manifestation of progression of CAD was found in the development of new lesions (44.6% of all patients or 79% of all progressing patients showed new lesions). Conclusions: Repeated coronary angiography on a quantitative basis offers an excellent opportunity to study the progression of coronary artery disease, especially also during preventive interventions. A limitation is the angiographic definition of progression, which has to be based on sound statistical criteria as data from direct comparisons with the abnormal anatomy are not available as of yet.