To investigate the intraindividual extent of cardiac allograft vasculopathy (CAV), 43 heart transplant recipients were studied 0.5 to 108 months after transplantation with intravascular ultrasound (IVUS). In these patients, 216 segments in 71 coronary arteries were analyzed quantitatively: 26 of 43 patients (60%) underwent study of > or = 2 arteries, and 80 of 216 segments (37%) were located distally (5.0 +/- 2.4 segments/patient were analyzed). Intimal index and mean IVUS grade were less pronounced in segments of the left circumflex artery (9 +/- 14 and 2.1 +/- 1.6) than in segments of the left anterior descending artery (21 +/- 19 and 3.3 +/- 2.1), right coronary artery (22 +/- 19 and 3.5 +/- 2.1), and left main coronary artery (16 +/- 4 and 3.3 +/- 1.9) (p < 0.01 and p < 0.001, respectively). In 21 of 43 patients, both the left anterior descending and left circumflex arteries were studied: Higher values in the intimal index were seen in the left anterior descending artery (20 +/- 14 vs 9 +/- 13, p < 0.005). When distal and proximal segments of the same vessel were compared, CAV was found in 44 of 56 arteries and the proximal segments were more affected in 64%. The difference between minimal and maximal IVUS grade in patients with only 1 artery studied (n = 17) was 1.7 +/- 1.8 compared with 3.1 +/- 1.7 in patients with > or = 2 arteries analyzed (n = 26). This in vivo study with IVUS shows a large variability of CAV involvement between different coronary arteries and segments in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)