Left anterior descending coronary artery flow after primary angioplasty in acute anterior ST-elevation myocardial infarction: how much flow is needed for left ventricular functional recovery?

Abstract

The treatment of choice in acute ST-elevation myocardial infarction (STEMI) is primary percutaneous coronary intervention (PPCI). Although, thrombolysis in myocardial infarction (TIMI) and myocardial blush grade (MBG) measures provide semi-quantitative flow evaluation after PPCI, serial and quantitative volumetric flow evaluation is still lacking.

Aim: Serial assessment of left anterior descending (LAD) coronary artery flow in patients with anterior myocardial infarction (MI), immediately after PPCI, 48 h later and pre-discharge and compare findings in patients with optimal and suboptimal PPCI result and their relation to left ventricular ejection fraction (LVEF).

Methods: Velocities in the LAD were recorded within 6 h after PPCI and one week later in 36 patients presenting with acute anterior STEMI. Sixteen patients had TIMI and MBG less than 3 after PPCI were considered to have suboptimal result. Sampling of LAD coronary artery velocity was obtained from trans-thoracic Doppler. Flow in the LAD coronary artery was estimated using heart rates, Doppler time velocity integrals and LAD color Doppler diameters.

Results: Diastolic LAD coronary artery flow immediately after PPCI in subjects with suboptimal PPCI, 29 ± 21 ml/min was lower than in those with optimal result, 39.8 ± 21 ml/min, p<0.05. Diastolic flow in the LAD coronary artery increased to 50.3 ± 28.5 ml/min two days after PPCI in patients with suboptimal PPCI, p=0.04, and to 49.6 ± 13.8 ml/min in those optimal result, p=0.04. LVEF increased by 9% in patients with optimal PPCI, p=0.004, and did not change in the other group.

Conclusions: (a) After PPCI, flow in the LAD coronary artery was dynamic; (b) in the presence of suboptimal PPCI, early LAD coronary artery flow was reduced; (c) pre-discharge, LAD coronary artery flow increased; and (d) LVEF increased only in optimal PPCI group associated with higher early LAD coronary artery flow.

Keywords: Doppler; ST-elevation myocardial infarction; left anterior descending coronary artery flow; left ventricular ejection fraction; primary angioplasty.