Cardiac troponin I predicts myocardial dysfunction in aneurysmal subarachnoid hemorrhage

OBJECTIVES We studied the incidence of myocardial injury in aneurysmal suba rachnoid hemorrhage (SAH) using the more sensitive cardiac troponin I (cTnI ) assay, correlated changes in cTnI with creatine kinase, MB fraction (CK-M B), myoglobin, and catecholamine metabolite assays, and examined the predic tive value of changes in cTnI for myocardial dysfunction. BACKGROUND Myocardial injury in aneurysmal SAH as evidenced by elevated CK- MB fraction has been reported. Little published data exist on the value of cTnI measurements in aneurysmal SAH. METHODS Thirty-nine patients were studied for seven days. Clinical cardiova scular assessment, electrocardiographic (ECG), echocardiography, cTnI, CK, CK-MB and CK-MB index, myoglobin and 24-h urinary catecholamine assays were performed in all patients. The ECG abnormalities were defined by the prese nce of ST-T changes, prolonged QT intervals, and arrhythmias. An abnormal e chocardiogram was defined by the presence of wall-motion abnormalities and a reduced ejection fraction. The severity of SAH was graded clinically and radiologically. RESULTS Eight patients demonstrated elevations in cTnI (upper limit of norm al is 0.1 mu g/liter with the immunoenzymatic assay and 0.4 mu g/liter with the sandwich immunoassay), while five had abnormal CK-MB levels (upper lim it of normal is 8 mu g/liter). Patients with more severe grades of SAH were more Likely to develop a cTnI leak (p < 0.05). Patients with cTnI elevatio ns were more likely to demonstrate ECG abnormalities (p < 0.01) and manifes t clinical myocardial dysfunction (p < 0.01) as evidenced by the presence o f a gallop rhythm on auscultation and clinical or radiological evidence of pulmonary edema as compared to those with CK-MB elevations. The sensitivity and specificity of cTnI to predict myocardial dysfunction were 100% and 91 %, respectively, whereas the corresponding figures for CK-MB were 60% and 9 4%, respectively. Elevations in myoglobin levels (upper limit of normal <70 mu g/iiter) and urinary catecholamine metabolites (urinary vanilmandelate/ creatinine ratio upper limit of normal, 2.6) are a nonspecific finding. CONCLUSIONS Measurements of cTnI reveal a higher incidence of myocardial in jury than predicted by CK-MB in aneurysmal SAH, and elevations of cTnI are associated with a higher incidence of myocardial dysfunction. Thus, cTnI is a highly sensitive and specific indicator of myocardial dysfunction in ane urysmal SAH. (J Am Coll Cardiol 2000;36:1328-35) (C) 2000 by the American C ollege of Cardiology.