Earlier studies have indicated that percutaneous transluminal coronary angioplasty (PTCA) of chronic total occlusions has a low success rate. To determine success rate and assess clinical and angiographic variables associated with success and complications, 57 total occlusions in 56 patients undergoing PTCA were analyzed. The clinical duration of occlusion was 51 +/- 86 days. Success (less than 50% residual stenosis) was achieved at 40 of 57 (70%) dilatation sites. Of these 57 total occlusions, 5 were attempted within 24 hours of acute myocardial infarction, 35 between 1 day and 8 weeks of clinical occlusion, 13 greater than 8 weeks and 4 were of unknown duration. Success rates were 4 of 5, 25 of 35, 9 of 13 and 2 of 4, respectively, in each group (difference not significant, comparison of all time groups). Of the 9 narrowings with a successful PTCA for an occlusion greater than 8 weeks, the mean duration of occlusion was 93 +/- 41 days (range 60 to 180). None of the attempted dilatations of occlusions with a clinical duration of greater than 180 days (n = 3) was successful. None of the clinical or angiographic variables (including tortuosity, length of occlusion gap, distance of the occlusion from the vessel origin, thrombus, lesion calcium, collaterals, prior myocardial infarction, vessel dilated or diffuse disease) impacted on success rate (difference not significant for all). No patient died, had a Q-wave infarction, required emergency coronary artery bypass grafting or underwent repeat PTCA within 7 days of the procedure. Non-Q-wave infarction occurred in 2 of 56 patients (4%).(ABSTRACT TRUNCATED AT 250 WORDS)