British Heart Foundation Centre of Excellence, School of Cardiovascular Medicine and Sciences, King's College London, United Kingdom (A.S., H.R., O.M.D., M.L.K., H.M., S.M.E., H.E., A.M.S., A.C., A.J.W., M.M., D.P.).
Guy's and St. Thomas' NHS Foundation Trust, London, United Kingdom (R.R., D.H., A.G., D.P.).
Circ Cardiovasc Interv. 2024 Jan;17(1):e013657. doi: 10.1161/CIRCINTERVENTIONS.123.013657. Epub 2023 Nov 6.
Myocardial bridges (MBs) are prevalent and can be associated with acute and chronic ischemic syndromes. We sought to determine the substrates for ischemia in patients with angina with nonobstructive coronary arteries and a MB in the left anterior descending artery.
Patients with angina with nonobstructive coronary arteries underwent the acquisition of intracoronary pressure and flow during rest, supine bicycle exercise, and adenosine infusion. Coronary wave intensity analysis was performed, with perfusion efficiency defined as accelerating wave energy/total wave energy (%). Epicardial endothelial dysfunction was defined as a reduction in epicardial vessel diameter ≥20% in response to intracoronary acetylcholine infusion. Patients with angina with nonobstructive coronary arteries and a MB were compared with 2 angina with nonobstructive coronary arteries groups with no MB: 1 with coronary microvascular disease (CMD: coronary flow reserve, <2.5) and 1 with normal coronary flow reserve (reference: coronary flow reserve, ≥2.5).
Ninety-two patients were enrolled in the study (30 MB, 33 CMD, and 29 reference). Fractional flow reserve in these 3 groups was 0.86±0.05, 0.92±0.04, and 0.94±0.05; coronary flow reserve was 2.5±0.5, 2.0±0.3, and 3.2±0.6. Perfusion efficiency increased numerically during exercise in the reference group (65±9%-69±13%; =0.063) but decreased in the CMD (68±10%-50±10%; <0.001) and MB (66±9%-55±9%; <0.001) groups. The reduction in perfusion efficiency had distinct causes: in CMD, this was driven by microcirculation-derived energy in early diastole, whereas in MB, this was driven by diminished accelerating wave energy, due to the upstream bridge, in early systole. Epicardial endothelial dysfunction was more common in the MB group (54% versus 29% reference and 38% CMD). Overall, 93% of patients with a MB had an identifiable ischemic substrate.
MBs led to impaired coronary perfusion efficiency during exercise, which was due to diminished accelerating wave energy in early systole compared with the reference group. Additionally, there was a high prevalence of endothelial and microvascular dysfunction. These ischemic mechanisms may represent distinct treatment targets.
心肌桥（MB）很常见，可与急性和慢性缺血综合征相关。我们旨在确定伴有左前降支 MB 的心绞痛且冠状动脉无阻塞患者的缺血底物。
接受静息、仰卧位踏车运动和腺苷输注期间的冠状动脉内压力和血流采集的心绞痛伴非阻塞性冠状动脉患者进行了冠状动脉波强度分析，其中灌流效率定义为加速波能量/总波能量（%）。定义心外膜血管内皮功能障碍为冠状动脉内乙酰胆碱输注引起的心外膜血管直径减少≥20%。将心绞痛伴非阻塞性冠状动脉和 MB 的患者与 2 个无 MB 的心绞痛伴非阻塞性冠状动脉患者组进行比较：1 个有冠状动脉微血管疾病（CMD：冠状动脉血流储备，<2.5），1 个有正常冠状动脉血流储备（参考：冠状动脉血流储备，≥2.5）。
92 例患者入组本研究（30 例 MB、33 例 CMD 和 29 例参考）。这 3 组的血流储备分数分别为 0.86±0.05、0.92±0.04 和 0.94±0.05；冠状动脉血流储备分别为 2.5±0.5、2.0±0.3 和 3.2±0.6。参考组在运动过程中灌流效率数值增加（65±9%-69±13%；=0.063），但 CMD（68±10%-50±10%；<0.001）和 MB（66±9%-55±9%；<0.001）组降低。灌流效率的降低有明确的原因：在 CMD 中，这是由舒张早期微循环衍生的能量引起的，而在 MB 中，这是由于上游桥导致收缩早期加速波能量减少引起的。MB 组的心外膜内皮功能障碍更为常见（54%比参考组的 29%和 CMD 组的 38%）。总体而言，93%的 MB 患者存在可识别的缺血底物。
MB 导致运动期间冠状动脉灌流效率受损，这是由于与参考组相比，收缩早期加速波能量减少所致。此外，还存在较高的内皮和微血管功能障碍发生率。这些缺血机制可能代表不同的治疗靶点。
Zotero 插件
