PROGNOSTIC INFLUENCE OF ELEVATED VALUES OF CARDIAC TROPONIN-I IN PATIENTS WITH UNSTABLE ANGINA

Background Elevations of the MB isoform of creatine kinase (CK) and ca rdiac troponin T seem to confer an adverse prognosis in unstable angin a. We examined whether this prognostic tic influence is also present f or cardiac troponin I (cTnI), a new and even more specific marker of m yocardial injury. Methods and Results We studied 106 patients with the clinical diagnosis of unstable angina showing chest discomfort at res t within 48 hours of admission, ECG evidence of myocardial ischemia, a nd normal values of total CK over the initial 16 hours of observation. The primary end point was death or nonfatal myocardial infarction (MI ) at 30 days; the secondary end point was the incidence of cardiac eve nts at 1 year. Blood was drawn every 8 hours for 3 days. Thirteen pati ents were excluded because of increased CK-MB mass concentrations with in 16 hours of admission (non-Q-wave MI) and 2 because of inadequate b lood sampling. Of the remaining 91 patients, 22 had cTnI elevations on admission (n=7) or after 8 hours (n=15). At 30 days, no deaths (0%) a nd 4 MIs (5.8%) occurred in the 69 patients with normal cTnI compared with 2 deaths (9.1%) and 4 MIs (18.2%) in the 22 patients with elevate d cTnI. The combined incidence of death and nonfatal MI was 5.8% and 2 7.3%, respectively (P=.02). At 1 year, only 68% of patients with eleva ted cTnI were free of cardiac events, compared with 90% of those witho ut elevations (P=.01). Conclusions These data indicate that cTnI is an important prognostic variable in patients with unstable angina. Eleva tions of cTnI predict an adverse short- and long-term prognosis.