Clinical presentation of myocardial infarction contributes to lower use of coronary angiography in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have high mortality following myocardial infarction (MI), but are less likely to undergo coronary angiography than those without CKD. Whether this phenomenon is explained by differences in the presentation of MI or by bias against performing coronary angiography in patients with CKD is unclear. We examined the clinical presentation of 1876 elderly patients who presented with MI and categorized them by estimated glomerular filtration rate: 460 ml/min (no/mild CKD), 30-60ml/min (CKD Stage 3) or < 30 ml/min (CKD Stage/5). Compared with patients with no/mild CKD, patients with CKD Stage 3 or Stage 4/5 had more comorbidity, greater prior nursing home use, and higher frequency of conduction abnormalities or anterior infarction. By contrast, peak creatinine kinase- MB fraction (CK-MB) concentrations were lower and ST- elevation MI was less common in patients with CKD Stage 3 or Stage 4/5. In univariate analyses, patients with CKD Stage 4/5 (odds ratio (OR) = 0.34, 95% confidence interval (Cl): 0.23 - 0.50) or Stage 3 (OR = 0.57, 95% Cl: 0.45 - 0.73) were markedly less likely to undergo angiography than subjects with no/ mild CKD. After multivariable adjustment, the association of CKD Stage 3 with the use of coronary angiography was attenuated (OR = 0.78, 95% CI: 0.60 - 1.03), but CKD Stage 4/ 5 remained strongly associated with lower use (OR 0.52, 95% Cl: 0.34-0.80). Clinical features of MI are different in patients with and without CKD and may partly explain the low use of angiography in patients with CKD Stage 3. However, the clinical features of MI do not account for its underuse in MI patients with CKD Stages 4/5. Whether reduced use of angiography in patients with advanced CKD is justified must be evaluated in formal risk- benefit analyses.