Pre-existing cardiac disease, troponin I elevation and mortality in patients with severe sepsis and septic shock

A prospective, observational study was undertaken to determine the frequency of troponin I elevation and the incidence of pre-existing cardiac disease in patients with severe sepsis and septic shock, and to determine their relationship to mortality. The setting was the surgical intensive care unit of a tertiary care medical centre. Sixty-six consecutive patients admitted with severe sepsis or septic shock requiring pulmonary artery catheterisation for haemodynamic monitoring were studied. Measurement of troponin I was done at the time of pulmonary artery catheterisation and every six to eight hours if there was ongoing tachycardia, hypotension or arrhythmias requiring treatment. Preexisting cardiac disease was determined from the patient and/or family members as well as from the medical record. Significant cardiac history was defined as prior myocardial infarction; abnormal treadmill report, nuclear medicine study or coronary angiogram; history of congestive heart failure or arrhythmia requiring treatment. Forty-two patients (64%) had elevated troponin I at study entrance and 23 patients (35%) had pre-existing cardiac disease. History of cardiac disease was associated with reduced cardiac index and oxygen delivery, and a nearly three-fold increase in mortality (44% vs. 16%, P = 0.03), irrespective of elevated troponin I levels. Troponin I elevation alone was not associated with increased mortality. We conclude that pre-existing cardiac disease and elevated troponin I are commonly found in surgical patients with severe sepsis and septic shock. In our study, pre-existing cardiac disease, and not troponin I elevation, was associated with increased mortality.