Purpose: To assess with cardiac magnetic resonance imaging (CMR) the relationship between treatment delay and improvement of regional left ventricular function after primary percutaneous transluminal coronary angioplasty (p-PTCA) for acute myocardial infarction (AMI).
Materials and methods: We performed cine- and late-enhancement (LE) CMR in 40 patients with first AMI after restoring TIMI 3 flow with p-PTCA and at a follow-up 4 months later. Infarcted segments were determined from LE images. Regional left ventricular function was quantified from cine-CMR images. Segmentation followed the American Heart Association 17-segments model. Patients were divided into groups with delay <3 hours, 3-6 hours, 6-12 hours, and a delay >12 hours.
Results: Segmental wall thickening (SWT) significantly iproved only in segments reperfused within 6 hours (P < 0.001). Follow-up SWT was significantly higher if segments were reperfused early (<3 hours: 74 +/- 4%, 3-6 hours: 57 +/- 4%, 6-12 hours: 48 +/- 7%, <3 to 3-6: P < 0.003, and <3 to 6-12 hours: P < 0.001). The extent of improvement was greater if delay was <3 hours compared to segments with a delay of >3 hours (<3 hours: +21 +/- 3%, 3-6 hours: +8 +/- 4%, 6-12 hours: +6 +/- 3%; <3 hours to 3-6 hours, and 6-12 h, P < 0.02).
Conclusion: We quantitatively demonstrated that time to p-PTCA treatment significantly influences regional functional recovery of infarcted myocardium at a 4-month follow-up.