Background: Whether myocardial perfusion grade (MPG) following late recanalization of infarct-related arteries (IRAs) predicts left ventricular (LV) function recovery beyond the acute phase of myocardial infarction (MI) is unknown.
Methods and results: The Total Occlusion Study of Canada-2 enrolled stable patients with a persistently occluded IRA beyond 24 hours and up to 28 days post-MI. We studied the relationship between the initial MPG and changes in LV function and volume as well as the change in MPG from immediate post-percutaneous coronary intervention (PCI) to 1 year in 139 PCI patients with thrombolysis in myocardial infarction grade 3 epicardial flow post-PCI and with paired values grouped into impaired or good MPG groups (MPG 0/1 or MPG 2/3). MPG 0/1 patients were more likely to have received thrombolytic therapy and to have a left anterior descending IRA. They had lower blood pressure and LV ejection fraction (LVEF) and a higher heart rate and systolic sphericity index at baseline. Changes in the MPG 0/1 and MPG 2/3 groups from baseline to 1 year were LVEF, 3.3±9.0% and 4.8±8.9% (P=0.42); LV end-systolic volume index (LVESVI), -1.1±9.2 and -4.7±12.3 mL/m(2) (P=0.25); LV end-diastolic volume index (LVEDVI), 0.08±19.1 and -2.4±22.2 mL/m(2) (P=0.67); and SDs/chord for infarct zone wall motion index (WMI), 0.38±0.70 and 0.84±1.11 (P=0.01). By covariate-adjusted analysis, post-PCI MPG 0/1 predicted lower WMI (P<0.001), lower LVEF (P<0.001), and higher LVESVI (P<0.01) but not LVEDVI at 1 year. Of the MPG 0/1 patients, 60% were MPG 2 or 3 at 1 year.
Conclusions: Preserved MPG is present in a high proportion of patients following late PCI of occluded IRAs post-MI. Poor MPG post-PCI frequently improves MPG over 1 year. MPG graded after IRA recanalization undertaken days to weeks post MI is associated with LV recovery, indicating that MPG determined in the subacute post-MI period remains a marker of viability.
Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00025766.