Histopathology of postpercutaneous transluminal coronary angioplasty remodeling in human coronary arteries

Background: We studied the histomorphometric correlates of long-term successful coronary balloon angioplasty (percutaneous transluminal coronary angioplasty [PTCA]). Restenosis after PTCA may occur secondary to the failure of compensatory arterial enlargement or post-PTCA arterial constriction. The histopathology of this process in human subjects remains poorly defined. Methods: Forty-two coronary segments from 41 patients treated with PTCA 60 ± 58 weeks before death were studied. The histomorphometric findings at the PTCA site were compared with those obtained at a proximal reference site. Results: Histologic long-term success was seen in 18 (43%) of 42 arteries. Histologically successful PTCA arteries (PTCA site lumen of ≥50% of the reference lumen) demonstrated a larger acute lumen, smaller plaque size (normalized to the internal elastic lamina area), and thinner adventitia compared with histologic failures. Relative to the reference sites, histologically successful PTCA showed expansion of the external elastic lamina. In contrast, histologic failures showed a reduced external elastic lamina area, suggesting constrictive remodeling. Neointimal area correlated with the extent of internal elastic lamina disruption, but neither variable was related to histologic PTCA success or failure. Conclusions: These data provide histomorphometric confirmation of the hypothesis that constrictive remodeling, not neointimal formation, determines the long-term outcome of PTCA.