Early evaluation of coronary microcirculation by echocardiography with contrast medium in patients with acute myocardial infarction treated with primary percutaneous transluminal coronary angioplasty.

Aim: In about 30% of patients with ST elevated myocardial infarction (STEMI), in which a TIMI 3 flow is obtained in the infarct related artery (IRA) after primary percutaneous transluminal coronary angioplasty (PTCA), it's not possible to obtain a good perfusion of coronary microcirculation (no reflow). Aim of the study is to estimate the prognostic value of microcirculation study by echocardiography with contrast medium (MCE) within 48 h from procedure and to point out if there're clinical or procedural factors correlated with no reflow.
Methods: From February 2002 to June 2003 we have analyzed the integrity of microcirculation by MCE in patients with STEMI treated with PTCA. We have included in this study 62 patients with anterior myocardial infarction (MI) (first event), within 12 h from symptoms onset, with great echocardiographic window and TIMI 3 flow in the IRA after PTCA, excluding shock. We have obtained the evaluation of myocardial perfusion by MCE within 48 h from the treatment. We have used Sonovue as contrast medium, infused through peripheral vein. In each patient we have measured: perfusion index (PI) (sum of single segments scores divided by total number of myocardial segments) and regional perfusion index (RPI) (number of normal perfused segments between the diskinetic ones divided by diskinetic segments). RPI varies from 0 to 1: when >0.5 it has been considered index of good perfusion. Ejection fraction (EF) and wall motion score index (WMSI) have been calculated within 48 h and at 6 weeks follow up. ST resolution (STR) has been evaluated at 90 min from procedure and it was considered significant when >70%.
Results: Patients have been divided into 2 groups by myocardial perfusion: group R (33 patients with RPI>0.5) and group NR (29 patients with RPI =/<0.5). The 2 groups were similar for age (group R: mean age 61 years old; group NR: mean age 64 years old, P=n.s.), glycoprotein inhibitors use (group R 90%, group NR 97%, P=n.s.), diabetes (group R 12%, group NR 17%, P=n.s.), hypertension (group R 22%, group NR 23%, P=n.s.), incomplete revascularization (group R 12%, group NR 10%, P=n.s.). Group NR has shown a major women percentage (33%) than group R (9%) P=0.026. In group R we have appreciated a trend to a major percentage of TIMI 2-3 flow preprocedure (66% vs 36%, P=n.s.), a shorter ischemic time (209 min vs 258 min, P=n.s.) and a major STR at 90 min (72% vs 53%, P=n.s.), not statistically significant. Echocardiographic analysis and MCE show a better myocardial perfusion in group R (RPI 0.7 vs 0.14 and PI 0.96 vs 0.86, P<0.0001); better left ventricular kinetics at 6 weeks follow up (EF 54.2% vs 50.8%, P=n.s. and WMSI 1.07 vs 1.2, P=0.014) but not in the acute phase (EF 46.8 vs 42.9 and WMSI 1.3 vs 1.34, P=n.s.) 30 days mortality is similar in the 2 groups (both 3%).
Conclusions: Myocardial perfusion evaluation correlates with left ventricular contractility measured at 6 weeks from acute MI, but doesn't correlate with contractility in the acute phase or 30 days mortality.