Comparison of functional recovery of mildly hypokinetic versus severely dysfunctional left ventricular segments after revascularization in patients with ischemic cardiomyopathy

Left ventricular remodeling after late revascularization correlates with baseline viability

The ideal management of stable patients who present late after acute ST-elevation myocardial infarction (STEMI) is still a matter of conjecture. We hypothesized that the extent of improvement in left ventricular function after successful revascularization in this subset was related to the magnitude of viability in the infarct-related artery territory. However, few studies correlate the improvement of left ventricular function with the magnitude of residual viability in patients who undergo percutaneous coronary intervention in this setting. In 68 patients who presented later than 24 hours after a confirmed first STEMI, we performed resting, nitroglycerin-enhanced, technetium-99m sestamibi single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) before percutaneous coronary intervention, and again 6 months afterwards. Patients whose baseline viable myocardium in the infarct-related artery territory was more than 50%, 20% to 50%, and less than 20% were divided into Groups 1, 2, and 3 (mildly, moderately, and severely reduced viability, respectively). At follow-up, there was significant improvement in end-diastolic volume, end-systolic volume, and left ventricular ejection fraction in Groups 1 and 2, but not in Group 3. We conclude that even late revascularization of the infarct-related artery yields significant improvement in left ventricular remodeling. In patients with more than 20% viable myocardium in the infarct-related artery territory, the extent of improvement in left ventricular function depends upon the amount of viable myocardium present. The SPECT-MPI can be used as a guide for choosing patients for revascularization.

Infarct zone viability influences ventricular remodelling after late recanalisation of an occluded infarct related artery

OBJECTIVE

To investigate the influence of infarct zone viability on remodelling after late recanalisation of an occluded infarct related artery.

METHODS

A subgroup of 26 volunteers from TOAT (the open artery trial) underwent dobutamine stress cardiovascular magnetic resonance at baseline to assess the amount of viable myocardium present with follow up to assess remodelling at one year. TOAT studied patients with left ventricular dysfunction after anterior myocardial infarction (MI) associated with isolated proximal occlusion of the left anterior descending coronary artery with randomisation to percutaneous coronary intervention (PCI) with stent at 3.6 weeks after MI (PCI group) or to medical treatment alone (medical group).

RESULTS

In the PCI group there was a significant relation between the number of viable segments within the infarct zone and improvement in end systolic volume index (-7.7 ml/m2, p = 0.02) and increased ejection fraction (4.1%, p = 0.03). The relation between viability and improvements in end diastolic volume index (-8.8 ml/m2, p = 0.08) and mass index (-6.3 g/m2, p = 0.01) did not reach significance (p = 0.27 and p = 0.8, respectively). In the medical group, there was no significant relation between the number of viable segments in the infarct zone and the subsequent changes in end diastolic (p = 0.84) and end systolic volume indices (p = 0.34), ejection fraction (p = 0.1), and mass index (p = 0.24).

CONCLUSION

The extent of viable myocardium in the infarct zone is related to improvements in left ventricular remodelling in patients who undergo late recanalisation of an occluded infarct related artery.