Patients undergoing PCI of the left internal mammary artery (LIMA) may have lower rates of recurrent myocardial infarction (MI) and repeat revascularization after one year, compared with those undergoing PCI of other arteries, according to a study published May 30 in the Journal of Invasive Cardiology.

Using data from ACC's CathPCI Registry, Khung-Keong Yeo, MBBS, FACC, et al., linked more than 1 million patient records to claims data from the Centers for Medicare and Medicaid Services to compare outcomes of PCI of the LIMA graft vs. different bypass grafts to the left anterior descending (LAD) coronary artery. Patients were placed into one of three groups based on graft type: LIMA, saphenous vein graft (SVG) or other. Primary outcomes were procedural success and one-year mortality; secondary outcomes were one-year rates of rehospitalization for MI, stroke and unplanned repeat revascularization.

A total of 10,051 patients received PCI on bypass grafts to the LAD. Of these, 3,011 (30%) were LIMA grafts, 6,797 (67.6%) were SVGs and 243 (2.4%) were other grafts. Procedural success was similar across the three groups (91.1% for LIMA, 92.9% for SVG and 93.4% for other). After one year, mortality was 14.8% for LIMA, 16.6% for SVG and 11.8% for other grafts. After adjustment, there were no statistically significant differences in one-year mortality across the three groups.

In terms of secondary outcomes, the rates of one-year MI rehospitalizations were 6.6% for LIMA, 9.9% for SVG and 8.1% for other grafts. Repeat revascularization occurred in 9.5% of LIMA patients, 14.4% of SVG patients and 10.4% of other patients. There were no significant differences in one-year stroke rates across the three groups. After adjustment, LIMA procedures vs. SVG procedures had lower rates of MI (hazard ratio [HR], 0.68; 95% confidence interval [CI], 0.60-0.40) and repeat revascularization (HR, 0.68; 95% CI, 0.59-0.79).

According to the researchers, the study demonstrates an association between LIMA procedures and lower rates of MI and repeat revascularization after one year, despite similar procedural success rates. The reasons for the lower MI and repeat revascularization rates are "likely multifactorial," they note, concluding that additional research is needed to validate the findings.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention

Keywords: Mammary Arteries, Coronary Vessels, Percutaneous Coronary Intervention, Saphenous Vein, Confidence Intervals, Medicaid, Medicare, Myocardial Infarction, Registries, National Cardiovascular Data Registries, CathPCI Registry, Stroke

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