Objective: To investigate the association of renal insufficiency and clinical outcomes in patients with acute coronary syndrome(ACS).
Methods: The study was a multi-centre register study including 3,589 ACS patients coming from 39 centers across China who had received percutaneous coronary intervention(PCI) prior to 1st February, 2007. Estimated glomerular filtration rate (eGFR) was calculated for all patients using the 4-variable MDRD equation with the serum creatinine obtained before angiography. The association between renal insufficiency and clinical outcomes and the presence of in-hospital death and bleeding was studied by Fisher's exact test. Multi-variable analysis on the risk factors of in-hospital bleeding was done by logistic regression test.
Results: The mean age of the study population was (61.74+/-11.37) years (ranging from 23 years to 92 years)and 76.5% (2,746/3,589) of the population was male. Only 90 patients (2.51%) were known to have chronic kidney disease at the time of admission and 144 patients(4.01%) had serum creatinine levels above 133 micromol/L. However, after the evaluation of renal status by the MDRD equation, 2,250 patients (63.1%)showed a reduction in eGFR of less than 90 mL/min, of whom, 472 (13.1%) even reached the level of moderate renal insufficiency (eGFR<60 mL/min) and above. Seven patients(0.20%) were proved to have chronic total occlusion lesions(CTO) and eight (0.22%) needed shift to coronary artery bypass grafting (CABG) after angiography. Both the presence of CTO lesions and CABG were proved to be associated with decrease of renal function through Fisher's exact test (P= 0.005 8 and 0.041, respectively). The in-hospital mortality rate was 0.47%(17/3 589) which was associated with the degree of renal insufficiency (P=0.001 3). A total of 75 patients(2.09%) of in-hospital bleeding were recorded with 26 patients(0.72%) diagnosed as major bleeding events. 92% (69/75) of the bleeding events occurred after PCI. Bleeding was found to be associated with the degree of renal insufficiency in every type of antithrombotic therapy (P<0.001). After adjusting with other variables by logistic regression test, renal insufficiency (eGFR per 10 mL/min decrease, OR=1.133, 95% CI 1.011- 1.27, P=0.032)and age (above 65 years, OR=1.907, 95% CI 1.107-3.28, P=0.02) were proved to be the risk factors of in-hospital bleeding.
Conclusion: Renal insufficiency is very common in ACS patients but self-report rate is low among this population. Renal function evaluated by eGFR should be carried out for every patient hospitalized for ACS for risk stratification. Patients with severer renal insufficiency usually have more complicated clinical manifestations and a higher rate of in-hospital bleeding.