Abstract

Objectives Slow flow phenomenon is a serious complication of percutaneous coronary intervention (PCI) and associated with poor prognosis. We sought to evaluate the characteristics of lesions predisposing to slow/no-reflow phenomenon during primary PCI in patients presenting with acute myocardial infarction.

Methods The study subjects consisted of 57 consecutive patients (mean 58.5±4.5 years old, 45 males) who underwent primary PCI for acute myocardial infarction and intravascular ultrasound-virtual histology (IVUS-VH) examination. Slow flow was defined as ≤ thrombolysis in myocardial infarction grade 2 after PCI.

Results Slow flow was developed in 12 patients (8 males). Patients with slow flow was likely to be older (67.5±3.8 yrs old vs. 56.2±3.9 yrs old, p=0.015), had more cardiogenic shock (16.7% vs. 2.2%, p=0.046), larger fibrofatty volume over the entire lesion length (36.7±25.5mm³ vs. 18.0±18.6mm³, p=0.006), higher remodeling index (1.10±0.17 vs. 0.99±0.16, p=0.043), larger plaque area (16.2±5.4mm² vs. 12.5±4.9mm², p=0.025), fibrous area(8.0±3.3mm² vs. 5.4±3.0mm², p=0.014), and fibrofatty area (2.7±2.2mm² vs. 1.3±1.6mm², p=0.016) at the minimal lumen site than those without slow flow (37 males). Multivariate analysis revealed that the fibrofatty volume over the entire lesion length was the only independent factor (beta=0.359, 95% confidence interval 0.002 to 0.012, p=0.006) for slow flow during primary PCI.

Conclusions This study suggests that slow flow may be dependent on the tissue characterization (fibrofatty volume) of the underlying lesion at the time of the primary PCI for acute myocardial infarction.