Watanabe Y, et al. - This study investigated determinants of slow flow after stent implantation, including factors associated with intravascular ultrasound (IVUS)-guided primary percutaneous coronary intervention (PCI). Consideration for modest stent expansion strategy was recommended for preventing slow flow following stent implantation in IVUS-guided primary PCI.

Methods

• Researchers performed this study in 339 ST-elevation myocardial infarction patients, who underwent stent deployment with IVUS.

Results

• Data reported that during PCI, 56 patients (16.5%) had transient or permanent slow flow.
• Researchers observed that a significant association was evident in multivariate logistic regression analysis, between slow flow and age (OR 1.04, 95% CI 1.01–1.07, P = 0.01), low attenuation plaque on IVUS (OR 3.38, 95% CI 1.70–6.72, P = 0.001), initial Thrombolysis In Myocardial Infarction (TIMI) flow grade 2 (vs. TIMI 0: OR 0.44, 95% CI 0.20–0.99, P = 0.046), and the ratio of stent diameter to vessel diameter (per 0.1 increase: OR 2.63, 95% CI 1.84–3.77, P < 0.001), respectively.
• They also noted that a ratio of stent diameter to vessel diameter of 0.71 had an 80.4% sensitivity and 56.9% specificity to predict slow flow.  
• Findings highlighted no significant difference in ischemic-driven target vessel revascularization between the modest stent expansion (ratio of stent diameter to vessel diameter <0.71) and aggressive stent expansion (ratio of stent diameter to vessel diameter ≥0.71) strategies.
• In addition, results showed that unlike other variables, the ratio of stent diameter to vessel diameter was the only modifiable factor.