Background: It is unknown whether patients with non-ST-elevation myocardial infarction derive a similar benefit from an early invasive therapy at different levels of renal function.
Methods and results: A total of 23 262 consecutive non-ST-elevation myocardial infarction patients <or=80 years old were included in a nationwide coronary care unit register between 2003 and 2006. Glomerular filtration rate (eGFR) was estimated with the Modification of Diet in Renal Disease Study formula. Patients were divided into medically or invasively treated groups if revascularized within 14 days of admission. A propensity score for the likelihood of invasive therapy was calculated. A Cox regression model with adjustment for propensity score and discharge medication was used to assess the association between early revascularization and 1-year mortality across renal function stages. There was a gradient, with significantly fewer patients treated invasively with declining renal function: eGFR >or=90 mL . min(-1) . 1.73 m(-2), 62%; eGFR 60 to 89 mL . min(-1) . 1.73 m(-2), 55%; eGFR 30 to 59 mL . min(-1) . 1.73 m(-2), 36%; eGFR 15 to 29 mL . min(-1) . 1.73 m(-2), 14%; and eGFR <15 mL . min(-1) . 1.73 m(-2)/dialysis, 15% (P<0.001). After adjustment, the overall 1-year mortality was 36% lower (hazard ratio 0.64, 95% confidence interval 0.56 to 0.73, P<0.001) with an invasive strategy. The magnitude of survival difference was similar in normal-to-moderate renal function groups. The lower mortality observed with invasive therapy declined with lower renal function, with no difference in mortality in patients with kidney failure (eGFR <15 mL . min(-1) . 1.73 m(-2)) or in those receiving dialysis (hazard ratio 1.61, 95% confidence interval 0.84 to 3.09, P=0.15).
Conclusions: Early invasive therapy is associated with greater 1-year survival in patients with non-ST-elevation myocardial infarction and mild-to-moderate renal insufficiency, but the benefit declines with lower renal function, and is less certain in those with renal failure or on dialysis.