Association of glycemic control with mortality in patients with diabetes mellitus undergoing percutaneous coronary intervention.

BACKGROUND Diabetes mellitus adversely affects outcomes in patients undergoing percutaneous coronary intervention. The association of baseline hemoglobin A1c (HbA1c) at the time of percutaneous coronary intervention with long-term mortality is unknown. METHODS AND RESULTS Consecutive patients with diabetes mellitus undergoing percutaneous coronary intervention between 1998 and 2008 were identified from our institutional database. Characteristics and outcomes of patients were compared based on HbA1c categories (≤7%, 7.1%-8.0%, 8.1%-9.0%, 9.1%-10.0%, and >10.0%). Among 3008 patients, 1321 had HbA1c ≤7%, 782 with HbA1c 7.1% to 8.0%, 401 with HbA1c 8.1% to 9.0%, 229 with HbA1c 9.1% to 10.0%, and 275 with HbA1c >10%. Compared with low HbA1c (≤7%), those with highest HbA1c (>10%) were younger (56.5 versus 67.5 years), had higher total cholesterol (188 versus 157 mg/dL), more insulin use (54% versus 26%), and presented more often with ST-segment-elevation myocardial infarction (10.9% versus 5.6%). Those with lower HbA1c (≤7%) more often had other comorbidities (more hypertension [90.4% versus 82.5%] and chronic renal failure [14.4% versus 7.6%]). On multivariable Cox proportional hazards modeling, survival analysis demonstrated a trend toward higher mortality with higher HbA1c. Compared with the reference group of patients with HbA1c ≤7%, patients with HbA1c >10% had a significantly higher mortality on follow-up (hazard ratio [95% confidence interval], 1.52 [1.17-1.99]; P=0.002). This difference was primarily seen among noninsulin users; however, insulin users had no significant differences in mortality among HbA1c categories. CONCLUSIONS Patients with diabetes mellitus who were not on insulin and had poor glycemic control (HbA1c >10%) had significantly higher long-term mortality after percutaneous coronary intervention as compared with those with well-controlled diabetes mellitus, evidenced by HbA1c ≤7%. Insulin users, however, had similar rates of mortality among different HbA1c categories.