Randomized trial of percutaneous coronary intervention for subacute infarct-related coronary artery occlusion to achieve long-term patency and improve ventricular function: the Total Occlusion Study of Canada (TOSCA)-2 trial

Abstract

Background: In the present study, we sought to determine whether opening a persistently occluded infarct-related artery (IRA) by percutaneous coronary intervention (PCI) in patients beyond the acute phase of myocardial infarction (MI) improves patency and indices of left ventricular (LV) size and function.

Methods and results: Between May 2000 and July 2005, 381 patients with an occluded native IRA 3 to 28 days after MI (median 10 days) were randomized to PCI with stenting (PCI) or optimal medical therapy alone. Repeat coronary and LV angiography was performed 1 year after randomization (n=332, 87%). Coprimary end points were IRA patency and change in LV ejection fraction. Secondary end points included change in LV end-systolic and end-diastolic volume indices and wall motion. PCI was successful in 92%. At 1 year, 83% of PCI versus 25% of medical therapy-only patients had a patent IRA (P<0.001). LV ejection fraction increased significantly (P<0.001) in both groups, with no between-group difference: PCI 4.2+/-8.9 (n=150) versus medical therapy 3.5+/-8.2 (n=136; P=0.47). Median change (interquartile range) in LV end-systolic volume index was -0.5 (-9.3 to 5.0) versus 1.0 (-5.7 to 7.3) mL/m2 (P=0.10), whereas median change (interquartile range) in LV end-diastolic volume index was 3.2 (-8.2 to 13.3) versus 5.3 (-4.6 to 23.2) mL/m2 (P=0.07) in the PCI (n=86) and medical therapy-only (n=76) groups, respectively.

Conclusions: PCI with stenting of a persistently occluded IRA in the subacute phase after MI effectively maintains long-term patency but has no effect on LV ejection fraction. On the basis of these findings and the lack of clinical benefit in the main Occluded Artery Trial, routine PCI is not recommended for stable patients with a persistently occluded IRA after MI.

Figure 1

IRA segment study eligibility criteria with LVEF ≥50% for (A) a left-dominant system, (B) a right-dominant system, and (C) right coronary artery in a right-dominant system. Eligibility when LVEF was >50% required that the occluded artery supply at least 25% of the LV.

Figure 2

TOSCA-2 study flow

Figure 3

Comparison of (A) baseline and follow-up LVEF (primary LV function end point; between group P=0.47), (B) LVESVI, and (C) LVEDVI in the 2 study groups. Box-and-whiskers plots indicate medians, means, and interquartile ranges. Probability values indicate baseline to 1-year comparisons within each group and between groups as indicated.