Association of cardiorespiratory fitness with characteristics of coronary plaque: Assessment using integrated backscatter intravascular ultrasound and optical coherence tomography

Background: Cardiorespiratory fitness (CRF) can predict future cardiovascular disease. Rupture of vulnerable plaque which often has a large lipid core with a thin fibrous cap causes acute coronary syndrome including sudden cardiac death. We tested our hypothesis that preserved CRF is associated with low lipid composition and thick fibrous cap thickness of coronary lesions. Methods: We prospectively performed both integrated backscatter intravascular ultrasound (IB-IVUS) and optical coherence tomography (OCT) for 77 non-culprit coronary lesions in 77 consecutive angina pectoris patients who underwent percutaneous coronary intervention (PCI). Percentage of achieved of predicted peak oxygen consumption (%PPeak Vo₂) calculated based on measured peak Vo₂ using a cardiopulmonary exercise test performed post PCI was adapted as an indicator of patient CRF. Results: Patients were divided into two groups [those with preserved CRF (%PPeak Vo₂ > 82%) (Group I) or others (Group II)]. Coronary plaques of Group I patients had significantly smaller lipid volume, greater fibrous volume, and thicker fibrous cap thickness than those of Group II (32 ± 14% vs. 45 ± 13%, p < 0.001; 57 ± 11% vs. 49 ± 11%, p < 0.001; and 177.7 ± 20.9 μm vs. 143.7 ± 36.9 μm, p < 0.001). In multivariate linear regression analysis, %PPeak Vo₂ showed a significantly negative correlation with lipid volume and a positive correlation with fibrous volume and fibrous cap thickness (β = - 0.418, p = 0.001; β = 0.361, p = 0.006; and β = 0.339, p = 0.008). Conclusions: High %PPeak Vo₂ was associated with low lipid volume, high fibrous volume and thick fibrous cap thickness in coronary lesions. These results may well suggest an attenuated risk of cardiovascular events in patients with preserved CRF.