Patterns of myocardial perfusion in the acute and chronic stage after myocardial infarction: a cardiac magnetic resonance study

Abstract

Objectives: The aim of the present study was to monitor the microvascular perfusion damage in the acute and chronic stage after myocardial infarction (MI) using first-pass dynamic magnetic resonance imaging (MRI). Furthermore we compared improvement of myocardial microcirculation and function in infarcted and non-infarcted left midventricular segments over a 4 months period.

Materials and methods: Cardiac magnetic resonance imaging (CMR) was performed in 46 consecutive patients within 8 days after successful reperfused first acute ST-elevation MI and 4 months thereafter. First-pass images were obtained by using Turbo-FLASH sequence during a bolus injection of Gd-based contrast agent. Signal-intensity-to-time (SIT) curves of 276 left ventricular myocardial segments were generated. Furthermore, infarct volumes as well as parameters of regional left ventricular function of corresponding segments were calculated.

Results: SIT curves highly significantly correlate with MI size (r=-0.57, r=-0.43 respectively; all p<0.0001) as well as with segmental wall thickening (SWT) of corresponding segments at baseline and follow-up scans (r=0.20, r=0.15 respectively; all p<0.02). SWT differ highly significantly between segments with and those without LE at baseline (p<0.003) and follow-up examinations (p<0.008), presenting either clear improvements at follow-up (all p<0.0001). In contrast, infarcted segments showing microvascular obstruction evidenced neither significant recovery of SIT nor of SWT (p=NS).

Conclusion: Our data indicate a close relationship between MI size and myocardial perfusion as well as function. Beyond epicardial artery patency, the assessment of quantitative parameters of myocardial perfusion and contractile function with the help of CMR appears to be a useful tool for estimating myocardial recovery after acute MI.