Longitudinal heterogeneity of coronary artery distensibility in plaques related to acute coronary syndrome.

BACKGROUND: How coronary distensibility contributes to stable or unstable clinical manifestations remains obscure. We postulated that the heterogeneous plaque distensibility is associated with unstable clinical presentations in patients with acute coronary syndrome (ACS). METHODS AND RESULTS: Seventeen and 19 ACS-related and -unrelated lesions, respectively, were visualized using intravascular ultrasound imaging with simultaneous intracoronary pressure recording. Systolic and diastolic lumen cross-sectional areas were measured at the lesion site and at five evenly spaced sites between the proximal and distal reference sites. The coronary distensibility index and stiffness index ß were calculated for each site and averaged for each coronary segment. Maximal distensibility index, standard deviation and the difference between maximal and minimal distensibility indices within each segment were significantly higher in the ACS-related than -unrelated plaques (5.6 ± 2.3 vs. 3.7 ± 1.8, p < 0.001, 2.1 ± 0.9 vs. 1.1 ± 0.6, p < 0.001 and 5.3 ± 2.3 vs. 2.8 ± 1.5, p < 0.001, respectively). Moreover, the difference in the distensibility index between the lesion site of ACS-related plaques and the immediate proximal site was significantly larger (2.88 ± 2.35 vs. 1.17 ± 1.44, p = 0.022) than that in ACS-unrelated plaques. CONCLUSIONS: Coronary artery distensibility is longitudinally more heterogeneous in ACS-related than-unrelated plaques, especially between the lesion and the immediate proximal site.

Endothelial dysfunction in paroxysmal atrial fibrillation as a prothrombotic state. Comparison with permanent/persistent atrial fibrillation.

AIM: Atrial fibrillation (AF), regardless of subtype, is associated with a prothrombotic state, which is related to endothelial dysfunction (ED).We hypothesized that paroxysmal atrial fibrillation (PAF) patients have endothelial dysfunction, and this may partially explain the high thromboembolic risk and poorer outcome in this category of patients. METHODS: The study population consisted of 100 consecutive outpatients with AF (mean age 65.9±7.9 years; 68 (68%) male) and 21 characteristics and comorbidity matched control subjects (mean age 64.8±7.0 years; 13 (61.9%) male). AF patients were divided into the PAF group (n=50) and permanent/persistent AF (PeAF) group (n=50).Reactive hyperemia pulse amplitude tonometry index (RHI) was measured to evaluate endothelial function. RESULTS: RHI was significantly lower in the PAF (1.67±0.30) and PeAF (1.63±0.28) groups in comparison with control subjects (2.12±0.40, both p< 0.001). There was no significant difference in RHI between the PAF and PeAF groups (p= 0.88). On linear regression analysis, both PeAF and PAF are significant independent predictors of RHI. CONCLUSIONS: In conclusion, ED in PAF patients was comparable to PeAF patients, and the presence of PAF itself is a contributing factor for ED independent of other coexisting comorbidities. This may provide a mechanism explaining why the risk of thromboembolism in PAF is comparable with PeAF patients.