Abstract 6028: Distal Coronary Artery Disease Has Less Calcification, Macrophage Infiltrates and Necrotic Core Area Compared to Proximal Disease, and Fewer Unstable Plaques in Sudden Coronary Death
Coronary artery plaque composition in distal vessels differs from that of proximal vessels, but quantitative data are not available. We selected 36 hearts at autopsy with severe coronary disease. There were 18 sudden coronary death (SCD, 69 ± 12 years) and 18 incidental coronary disease (58 ± 15 years). Hearts were perfusion fixed and computerized morphometry was performed on all 3 mm segments > 50% area luminal stenosis. Proximal lesions were those with lumen diameter > 3 mm and distal lesions < 2.5 mm diameter. Total numbers of fibroatheromas (FA), thin-cap fibroatheromas (TCFA), and healed plaque ruptures (HPR) were quantitated in proximal and distal segments. There were a total of 1317 sections (37 ± 5 per heart) studied histomorphometrically. In SCD, there were 143 proximal FAs (mean 8.1 per heart, 33% of plaques) and 54 distal FAs (mean 3.0 per heart, 26% of plaques, p=0.2 vs. proximal); 42 proximal TCFAs (mean 2.3 /heart, 10% of plaques) and 3 distal TCFA (mean 0.2 /heart, 1% of plaques, p<.001 vs. proximal); and 113 proximal HPR (mean 6.6 /heart, 26% of plaques) and 13 distal HPR (mean 0.7 /heart, 6% of plaques, p<.0001 vs. proximal). Mean necrotic core area was 11% in proximal lesions vs. 5% distally, (p<.0001); mean calcified area was 10% proximally vs. 8% distally (p<.008), and mean macrophage content was 2.1% proximally vs, 0.9% distally (p<.0001). In incidental disease, there were 78 proximal FAs (25% of lesions), 6 distal FAs (9% of lesions)(p=.0.2 vs. proximal); 12 proximal TCFAs (4% of plaques) and 1 distal TCFA (1% of plaques)(p=.7 vs. proximal); 39 proximal HPR (12% of plaques) 8 distal HPRs (11% of plaques)(p=0.8). Mean necrotic core area was 7% proximally and 2% distally (p<.0001), mean calcified area 16.4 proximally and 5.3 distally (p<.0001); and mean macrophage area 1.5 proximally and 1.1 distally (p<.001). In both symptomatic and asymptomatic coronary disease, there is more inflammation, calcification and necrotic core proximally. In sudden coronary death, the increase in unstable plaques compared to incidental disease is primarily in proximal sites. The lesser degree of calcification, inflammation and necrotic core formation in distal vessels may effect optimal stent design, as well as immediate and long-term results of coronary artery stenting.