Elevated cTnT post-ICD discharge signals death risk

3 July 2009

MedWire News: Cardic troponin T (cTnT) elevation after implanted defibrillator discharge predicts survival, US researchers have revealed.

Discharge of an implantable cardioverter defibrillator (ICD) was a risk factor for death even if it occurred after device testing, and remained so independently of common prognostic variables.

The team at Yale University School of Medicine in Bridgeport, Connecticut, tracked the clinical course of all patients who had received an ICD at their institution since January 2000.

Any who reported spontaneous ICD discharges were asked to come in for evaluation within 12 to 24 hours to examine the ICD and assay cTnT levels. From the start of 2003, the team also assessed cTnT levels after ICD testing.

By 2009, 174 patients had received ICD discharge, with this being spontaneous in 66 and induced in 108. Their mean age was 68 years, and mean left ventricular ejection fraction (LVEF) was 29%.

Patients received between one and 19 discharges, with total delivered energy ranging from 6 to 288 J.

Blood for testing was obtained a mean of 17 hours after spontaneous discharge or device testing. cTnT levels were 0.05 ng/ml or above in 24% of patients, and these individuals also had higher mean serum creatinine than others but no other significant clinical differences.

During a median follow-up period of 41.8 months, 56 patients died. cTnT levels were at least 0.05 ng/ml in 48% of those who died but just 12% of those who survived (p<0.001).

The significant relationship between raised cTnT and survival remained after adjusting for total ICD energy delivered during an arrhythmia episode, age, gender, presence of coronary artery disease, LVEF, and serum creatinine.

Reporting in the journal Heart, the researchers say: “Though the mechanism remains uncertain, such cTnT release may indicate underlying myocardial metabolic ‘fragility’ in patients with heart disease.”

MedWire is an independent clinical news service provided by Current Medicine Group, a part of Springer Science+Business Media. © Current Medicine Group Ltd; 2009

Heart 2009; 95: 1153-1158