Should cardiac troponins be used as a risk stratification tool for patients with chronic critical limb ischaemia?

Cardiovascular mortality in patients with chronic critical lower limb ischaemia (CCLI) is high and early risk stratification in these patients may aid clinical management improving outcomes. Cardiac troponin I (cTnI) has prognostic significance in patients with unstable angina. The aim of this study was to evaluate the prognostic significance of cardiac troponins in CCLI patients who had no clinical evidence of unstable coronary heart disease.

Patients (n=152) admitted with CCLI to a single vascular unit over a two-year period were included prospectively in this study. Patients with clinical evidence of unstable coronary disease were excluded from the study. Patient demographics, clinical history, co-morbidity and risk factors for peripheral vascular disease were documented. Admission cTnI levels were recorded using a threshold, 0.1 ng/ml. The primary endpoint was mortality.

Fifty-two patients (34.2%) had an elevated cTnI, whilst 100 (65.8%) had cTnI <0.1 ng/ml. Sixty-two patients died during the follow-up period, 38 with an elevated admission cTnI. Death rate in patients with cTnI >0.1 ng/nl was 73% compared with 24% in those with levels below the threshold (p<0.0001). Patients with elevated cTnI were significantly older than those with normal level (median age 76 years vs 71 years, p<0.001). An elevated cTnI was found to independently predict disease-specific mortality on Cox regression analysis (Hazard Ratio 4.2; 95% Confidence Interval 1.3-12.7).

In this series of patients with CCLI the measurement of cTnI on admission was a significant independent predictor of survival. cTnI has potential as a prognostic test to stratify patients with a high cardiovascular risk and may enable further optimisation of these high-risk patients.