Comparison of C-Reactive Protein Levels with the Stress Test for Non-Invasive Risk Stratification of Patients Recovering from Unstable Angina

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Abstract

Objective To compare the prognostic value of the stress test with C-reactive protein levels for non invasive risk stratification in patients with unstable angina, dis-charged without in-hospital events or revascularization procedures. Methods One hundred and four consecutive patients with unstable angina free of in-hospital events or revascularization were included. Measurement of C-reactive protein and a stress test (70.2% treadmill test,29.8% stress echo) were performed at hospital dis-charge. Results A value of 1.5 mg/dl was established as the cutoff point between normal and elevated C-reactive protein levels according to our previous study. After a90-day follow-up, the incidence of death, myocardial infarction or refractory angina was higher inpatients with a positive stress test (56.8% vs. 14.9%,p<0.001) or C-reactive protein levels above 1.5 mg/dl (84.8% vs. 4.2%, p<0.001). Patients who had both an elevated C-reactive protein and a positive stress test had a 90-day incidence of death, myocardial infarction or refractory angina higher than that observed with either an isolated C-reactive protein elevation or a positive stress test, whereas patients in whom both tests were negative were at very low risk (95.0%, 69.2%, 11.8% and 1.9% respectively; p< 0.001). In a Cox regression model C-reactive protein was the strongest independent marker of an adverse 90-day outcome (HR 9.1, IC 95% 3.3-12.5; p<0.001). Conclusions At hospital discharge the combination of markers of inflammation ("subclinical plaque instability") and restriction to coronary flow ("impaired coronary reserve") improves the identification of patients at higher risk of future events.