Left ventricular remodelling and microvascular circulation after distal coronary protection during primary percutaneous coronary intervention in acute myocardial infraction

It was known that distal coronary protection during primary PCI had no long-term effects on ventricular remodelling is not well established. This prospective randomised study was designed to validate the efficacy of distal coronary protection on ventricular remodelling and microvascular obstruction at 6 months after AMI. AMI patients with onset time of 12 h or less were randomly assigned into the distal coronary protection group (group P) with percutaneous guardwire, or no protection group (group N). Immediately after PCI, antegrade flow and myocardial perfusion were evaluated according to TIMI and TMP grading, respectively. QCA (quantitative coronary angiography) analysis, at the time of immediate post-PCI and 6 months follow-up and clinical outcome during follow-up period. Before the discharge, cardiac MRI imagings were obtained. Microvascular obstruction (MVO) was graded in perfusion imaging. Grade III means severe degree of MVO showing no evidence of microperfusion after 10 min of contrast injection. 88 patients were enrolled and among them, 66 patients including 2 mortality cased finished 6 months follow-up. No difference was found in demographic characteristics and major risk factors. Stent was longer in group P (27.23 mm vs. 24.36 mm, p = 0.03) and similar in diameter (3.17 mm vs. 3.10 mm, p = 0.48). Distal protection did not show any benefit in terms of left ventricular volume, infraction size measured by cardiac MRI, post-PCI and 6 months follow-up. MRI ejection fraction had no difference both at baseline and 6 months follow-up. TMP grade III was 40% in group P, 29% in group N, (p = 0.07) MVO grade 0/I was 27% in group P, 35% in group N immediately after PCI. Distal protection device have tendency to improve microvascular perfusion but it seems not to affect the ventricular remodelling and dysfunction.