Comparison of outcomes after percutaneous coronary revascularization with stents in patients with and without mild chronic renal insufficiency

Abstract

R studies have shown that patients with mild chronic renal insufficiency (CRI) have a high prevalence of cardiovascular disease and cardiac death. Furthermore, patients with CRI undergoing percutaneous coronary intervention have a higher rate of in-hospital and long-term morbidity and mortality. A recent retrospective subgroup analysis of patients with CRI undergoing percutaneous intervention suggests that the use of stents may improve their in-hospital and long-term outcomes. Therefore, the purpose of this study was to analyze the shortand long-term outcomes and the predictors of mortality after percutaneous coronary revascularization with stents in patients with mild CRI compared with patients with normal renal function. • • • Using an interventional database whereby clinical, demographic, procedural and follow-up data are entered by dedicated, independent research personnel unaware of the objectives of the study, we identified a total of 554 consecutive patients with mild CRI and 4,530 consecutive patients with normal renal function who underwent coronary stenting between January 1995 and January 2000. Clinical follow-up was performed by either telephone contact or office visit at 6 and 12 months. The occurrence of major late clinical events were recorded (including death, Q-wave myocardial infarction, and revascularization procedures). All events were source documented and adjudicated. Mild CRI was defined as the presence of previously documented renal insufficiency and/or a baseline serum creatinine above the normal range ( 1.4 mg/dl in women or 1.5 mg/dl in men) but 3.0 mg/dl. Patients on dialysis were excluded from the analysis. Creatinine clearance (CrCl) was calculated applying the Cockcroft-Gault formula using the baseline serum creatinine: CrCl 140 age weight/serum creatinine 72 with female gender adjustment ( CrClfemale CrCl 0.85 ). Hypercholesterolemia was defined as a serum cholesterol 240 mg/dl. Q-wave myocardial infarction was defined by the presence of new pathologic Q waves on the electrocardiogram associated with an elevation of cardiac enzyme at least 2 times the upper normal values. Renal function deterioration was defined as an increase in serum creatinine levels 0.5 mg/dl from baseline. Non–Q-wave myocardial infarction after intervention was defined as a creatine kinase-MB fraction elevation 5 times the upper normal value without new Q waves. Clinical success was defined as successful revascularization in the absence of death, myocardial infarction, or emergency coronary artery bypass graft surgery. Major bleeding was defined as a reduction in hemoglobin 5 g/dl (or 15% in hematocrit), retroperitoneal bleeding, or any intracranial bleeding. Vascular complications were defined as the need for surgical repair, large hematoma, pseudoaneurysm, or fistula. Patients diagnosed with CRI underwent routine intravenous hydration with 1/2 normal saline, 75 to 100 ml/hour, for 12 hours before and for 6 hours after the procedure; an ionic low osmolar contrast agent (ioxaglate meglumine, Hexabrix, Mallinkrodt Medical Inc.) was used. Weight-adjusted heparin dosage was administered during the procedure to maintain an activated clotting time of 250 to 300 seconds. Patients received aspirin 325 mg at least 24 hours before the procedure and continued indefinitely afterward, and they were also treated concomitantly with either ticlopidine 250 mg twice daily for 4 weeks or clopidogrel 75 mg/day for 2 weeks according to routine protocol. Statistical analyses were performed using SAS 6.10 (SAS Institute, Cary, North Carolina). Continuous variables are presented as mean 1 SD and are compared using Student’s t test or regression analysis. Categorical variables are presented as percentages and are compared using the chi-square test or Fisher’s exact test. Kaplan-Meier survival curves were used to compare freedom from death. Multivariate logistic analysis with backward regression was used to model independent predictors of late mortality. Variables included in the multivariate model were age, gender, previous infarction, CRI, diabetes mellitus, saphenous vein graft intervention, left ventricular ejection fraction, and history of coronary bypass surgery. A p value 0.05 was considered significant. Between January 1995 and January 2000, a total of 554 consecutive patients with mild CRI, not on dialFrom the Cardiac Catheterization Laboratory and the Cardiovascular Research Institute, Washington Hospital Center, Washington, DC. Dr. Gruberg’s address is: Cardiovascular Research Institute, Washington Hospital Center, 110 Irving Street, NW, Suite 4B-1, Washington, DC 20010. E-mail: gruberg67@hotmail.com. Manuscript received May 8, 2001; revised manuscript received and accepted September 5, 2001.