Impact on slow-flow/no-reflow of intravascular ultrasound-guided primary percutaneous coronary intervention in ST-elevation myocardial infarction

Abstract

Background: Intravascular imaging (IVI) using intravascular ultrasound (IVUS) or optical coherence tomography is now strongly recommended to guide percutaneous coronary intervention (PCI), as studies have shown reduced rates of stent thrombosis and target lesion failure. Benefits seem to be greater in acute coronary syndrome, especially when optimal PCI criteria are met. Despite these positive results and the fact that IVUS was introduced almost 30 years ago, IVI is far from having become a routine tool in everyday clinical practice in Europe and the United States. In ST-elevation myocardial infarction (STEMI), the acute risk of slow-flow/no-reflow associated with post-stenting optimization and loss of time in emergency situations are cited as reasons, in addition to cost concerns and lack of availability.

Methods: In this case control study, 96 STEMI patients were assigned 1:2 to either IVUS-guided primary PCI (PPCI) (32 patients) or angiography-guided PPCI (64 patients). In the IVUS group, once a thrombolysis in myocardial infarction (TIMI) 3 flow was restored with minimalist immediate mechanical intervention, IVUS was performed before stenting for sizing, followed by direct stenting and angiography-guided optimization if necessary, with IVUS performed again after stenting until the result was considered optimal. In the control group, TIMI 3 flow restoration, predilatation, stenting, and postdilatation were left to the physician's discretion based on angiographic assessment. Primary endpoint was the occurrence of slow-flow/no-reflow as assessed by TIMI flow score. Secondary endpoints were procedure time, contrast volume, X-ray exposure, distal embolization, in-hospital complications, and 1-month complications.

Results: Primary endpoint (slow-flow/no-reflow) occurred in 11/32 (34.4%) patients in the IVUS group and in 22/64 (34.4%) patients in the control group (p=1.00) and was similar in patients with optimal IVUS-guided PCI criteria (5/19 [26.3%]) and in the suboptimal PCI group (4/11 [36.4%]; p=0.687). Regarding the secondary endpoints, there was no difference in X-ray time (median of 760 s in the control group vs. 787 s in the IVUS group; p=0.529), procedure time (median of 32 min vs. 34 min; p=0.278), contrast volume (165 ml vs. 150 ml; p=0.319), and radiation dose (dose area product 5353 cGy.cm² vs. 4745 cGy.cm²; p=0.633). Similar results were obtained for per-procedure complications, especially for distal embolization (5/64 [7.8%] in the control group vs. 2/32 [6.3%] in the IVUS group; p=1.000). Slow-flow/no-reflow increased the risk of ventricular arrhythmia during the procedure (9% vs. 0%; p=0.038), and was associated with higher troponin (6612 ng/L vs. 3972 ng/L; p=0.025) and C-reactive protein (33 ng/L vs. 15.4 ng/L; p=0.032) levels, lower left ventricular ejection fraction (median of 45% vs. 50%; p=0.006), and more complications during the index hospitalization and at 1 month, mainly consisting in heart failure (21% vs. 4.8%, p=0.029 during index hospitalization; 9.7% vs. 0%, p=0.040 at 1 month). Major adverse cardiovascular events at 1 month were also more frequent in patients who experienced slow-flow/no-reflow (9.68% vs. 0%; p=0.040).

Conclusion: In STEMI, IVUS-guided PPCI appears to be safe without increasing slow-flow/no-reflow occurrence in case of direct stenting, and without increasing procedure time, contrast volume, and complications when performed in an experienced center.

Keywords: IVUS-guided percutaneous coronary intervention; ST-elevation myocardial infarction; angiography-guided percutaneous coronary intervention; no-reflow; slow-flow.