MG Shlipak, VA San Francisco; PA Heidenreich, VA Palo Alto; H Noguchi, Stanford Medical Center; M McClellan, Stanford Medical Center; WS Browner, VA San Francisco

Objectives: The effects of renal insufficiency on survival after myocardial infarction (MI) have not been well characterized. We hypothesized that patients with renal insufficiency would have increased mortality, in part because they would be less likely to receive appropriate treatment compared to patients with normal renal function.

Methods: The Cooperative Cardiovascular Project collected data via chart abstraction on elderly (>65 years) patients with MI from April 1994 through July 1995. Based on the initial serum creatinine (Cr) level, we categorized patients as having no (Cr<1.5mg/dl; n=82,455), mild (Cr1.5-2.4 mg/dl; n=36,756), and moderate renal insufficiency (Cr 2.5-3.9 mg/dl; n=10,888). We also estimated creatinine clearance using the Cockroft-Gault equation, and divided patients into tertiles of renal function. Multivariate proportional hazard models were used to adjust for differences in patients characteristics and treatment in-hospital.

Results: Patients with renal insufficiency were less likely to receive aspirin, beta-blockers, thrombolytic therapy, angiography,and revascularization. One-year mortality varied from 24% (patients with no renal insufficiency) to 46% (mild renal insufficiency to 66% (moderate renal insufficiency). After adjustment for patient characteristics, comorbidity, and severity of MI , mild renal insufficiency (RR=1.43; 95% CI:1.40-1.47) and moderate renal insufficiency (RR=2.01; 95% CI: 1.94-2.07) were associated with increased mortality compared to no renal insufficiency. Adjusting for treatment differences markedly attenuated the increased mortality associated with mild renal insufficiency (RR=1.15; 95% CI: 1.07-1.24) and moderate renal insufficiency (RR=1.40; 95% CI: 1.27-1.55).

Conclusions: Renal insufficiency is an independent risk factor for mortality after myocardial infarction. Under-utilization of beneficial therapies contributes to the high mortality in these patients.

Impact: Interventions are urgently needed to improve the care of this high-risk subgroup of patients with myocardial infarction.