Troponin I as a marker of right ventricular dysfunction and severity of pulmonary embolism

Cardiac troponin I (cTnI) is a specific marker which allows detection of minor myocardial cell damage. In patients with severe pulmonary embolism (PE), the rise in pulmonary artery pressure can lead to progressive right ventricular dysfunction (RVD), and clinical studies have demonstrated the presence of ischemia and even right ventricular infarction. Our aims were to determine the prevalence and diagnostic utility of cTnI in identifying patients with RVD and to ascertain whether it correlates with severity of PE.

We studied 77 patients with PE diagnosed by pulmonary angiography, ventilation-perfusion lung scan, spiral computed tomography scan or a combination of abnormal echocardiogram with clinical presentation suggestive of PE or with positive subsidiary exams (d-dimers, venous Doppler of the lower limbs, ECG, blood gas analysis). We further classified the PE according to the European Society of Cardiology severity levels, the PE being: 1) massive, if there was shock and/or hypotension; 2) submassive, if we found right ventricular hypokinesis on the echocardiogram; and 3) non-massive, in the remaining cases. We considered the highest cTnI serum value from the admission to 24 hours and a normal value of < 0.10 ng/ml.

Among the 60 patients with cTnI measurements, 42 had elevated values. Among those with RVD, 26 (81.3%) had increased cTnI levels and only 14 (35%) with elevated cTnI values did not have RVD, indicating that positive cTnI tests were significantly associated with RVD (p = 0.038). Patients with positive cTnI tests had earlier onset of symptoms (24.0 vs. 144.0 hours, p=0.02), higher prevalence of emboli in proximal vessels (pulmonary trunk and right or left main pulmonary arteries) (OR = 12, CI= 1.6-88.7), and received more thrombolytic therapy (OR = 5.4, CI = 1.1-26.8) than those with normal cTnI tests. cTnI levels were higher among patients with submassive PE (median: 0.77 ng/ml) and lower in those with non-massive PE (0.08 mg/ml, p < 0.05).

Around 70% of patients with PE have elevated cTnI values and this test is significantly associated with RVD. cTnI measurements provide additional information in the evaluation of patients with PE by identifying more severe cases and those at increased risk of hemodynamic deterioration, who can benefit from more aggressive therapeutic strategies.