BACKGROUND There is a paucity of information regarding the impact of the coronary collaterals on prognosis in type 2 diabetic (T2DM) patients. We developed a novel index, which considers not only the degree of collateral circulation but also the stimulus of collateral development, and investigated its prognostic value in T2DM patients with coronary artery disease (CAD).

METHODS AND RESULTS One hundred and ninety four consecutive T2DM patients were analyzed and followed for an average of 30 months. We measured the diameter stenosis (DS; %), corrected TIMI frame count (CTFC) and Rentrop score at 3 major epicardial coronary arteries. The collateral development (CD) score was calculated by: (Sigma Rentrop score +1)/Sigma [DS (%) x CTFC] x1,000. During the follow-up, acute cardiovascular events occurred in 49 patients. By multivariate analysis, the CD score was an independent predictor of adverse events not only in the total population (p<0.001), but in all 3 subgroups (p=0.020 for coronary artery bypass grafting, p=0.030 for percutaneous transluminal coronary angioplasty (PTCA) and p=0.003 for the medical group). Furthermore, patients in the tertile with the highest CD score showed improved survival by Kaplan-Meier analysis in the total population, the PTCA and the medical group.

CONCLUSIONS The CD score, a novel index of collateral development, may be a useful predictor of clinical outcome in T2DM patients with CAD.