Documentation of Transient Microvascular Dysfunction Caused by Percutaneous Transluminal Coronary Rotational Atherectomy With Myocardial Contrast Echocardiography

Background. Chest pain, ST segment elevation and slow flow are recognized as the complications of percutaneous transluminal coronary rotational atherectomy (PTCRA). But the relation between these complications and microvascular dysfunction remains unknown. We assessed the impact of PTCRA on coronary microvascular function with myocardial contrast echocardiography (MCE). Methods. Consecutive 36 patients with stable effort angina underwent PTCRA using the continuous infusion of verapamil into the target vessel. MCE was performed with the intracoronary injection of sonicated microbubbles before, during or shortly after, and after PTCRA procedure. We measured baseline-subtracted peak intensity (256 gray scales) in the risk zone and in the normal zone, and calculated the ratio of the former to the latter (PI ratio). We divided the patients into two groups based on the presence or absence of ST elevation during PTCRA, group-A (n=20) = present and group-B (n=16) = absent. Results. Before PTCRA, there was no difference in PI ratio between two groups (A vs. B; 0.85±0.32 vs. 0.77±0.23). During or shortly after PTCRA, PI ratio in group-A was significantly lower than that in group-B (0.29±0.26 vs. 0.90±0.19, p<0.05), but only 5 patients of group-A showed angiographical slow flow. In group-A, ST elevation resolved to baseline 15±9 min later, and PI ratio increased to baseline level at this moment (0.83±0.28). Conclusions. MCE study reveals that PTCRA produces microvascular dysfunction much more frequently than expected from angiographical findings. This microvascular dysfunction was not fully protected by verapamil, but it is transient and myocardial flow quickly recovers to the baseline level.