Introduction and objectives: Before including troponin I detection in the daily practice of our hospital we performed a prospective study to determine its real usefulness and to establish the best cut-off point.
Methods: We studied 82 consecutive patients admitted with unstable angina to a community hospital. Troponin I was determined (> 10 h after chest pain). Patients were referred to a tertiary hospital for catheterization/revascularization if clinical events developed.
Results: Twenty-five patients (31%) suffered events during admission: recurrent angina in 23 cases (28%); heart failure in 5 (6%); exitus in 3 (4%); myocardial infarction in 1 (1%). The cut-off point for troponin I that best predicted events was 0.1 ng/ml. Patients with troponin I > 0.1 (34 patients, 42%) experienced more events [47 vs. 19%; OR = 3.8 (1.4-10.4); p = 0.01] and had higher rates of recurrent angina (42 vs. 19%), heart failure (12 vs. 2%) and exitus (9 vs 0%). Patients with ECG changes and troponin I > 0.1 showed a significantly higher percentage of events (63%) than those with ECG changes alone (23%) or troponin I > 0.1 alone (15%) or those without ECG changes and troponin I < 0.1 (17%) (p < 0.0001).
Conclusions: Troponin I elevation is useful for predicting in-hospital risk for unstable angina patients admitted to a community hospital. A low cut-off value (0.1 ng/ml) predicts events. The association of ECG changes and high troponin I identifies a population at very high risk; however, the absence of both variables in patients with a diagnosis of unstable angina does not preclude the development of events.