Association of slow flow with clinical factors in intravascular ultrasound-guided percutaneous coronary intervention for patients with left main trunk-acute myocardial infarction.

BACKGROUND: Slow flow can be fatal in primary percutaneous coronary interventions for left main trunk (LMT)-acute myocardial infarction (AMI), however, risk factors for slow flow in LMT-AMI have not been well investigated. Intravascular ultrasound (IVUS) may help to stratify the high-risk lesion for slow flow in LMT-AMI.

METHODS: A total of 51 LMT-AMI were included as the study population, and were divided into the slow-flow group (n=22) and the non-slow-flow group (n=29). Slow flow was defined as either transient or persistent Thrombolysis in Myocardial Infarction (TIMI) flow grade ≤2.

RESULTS: The incidence of in-hospital death was higher in the slow-flow group (27.3%) than the non-slow-flow group (10.3%) without reaching statistical significance (p=0.116). Although the reference diameter measured by angiography was not different between the two groups, the vessel diameter measured by IVUS was significantly longer in the slow-flow group (5.22±0.69mm) than in the non-slow-flow group (4.50±0.47mm) (p<0.001). Multivariate logistic regression analyses revealed that the vessel diameter by IVUS (OR 27.487, 95%CI 3.975-190.062, p=0.001) and the vessel area by IVUS (OR 1.458, 95%CI 1.160-1.832, p=0.001) were significantly associated with slow flow.

CONCLUSIONS: In LMT-AMI, the vessel diameter measured by IVUS was closely associated with slow flow, while the reference diameter measured by angiography was not associated with slow flow. IVUS would be important to find high-risk features for slow flow in LMT-AMI.