Contrast-enhanced MRI stratifies chronic MI patients for prophylactic ICD

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Contrast-enhanced cardiovascular MRI prior to prophylactic implantation of a cardioverter defibrillator identifies patients with increased risk for ventricular arrhythmias, which could prevent adverse events and save money, according to a study presented at the recent meeting of the Society of Cardiovascular Magnetic Resonance in Orlando.

Philipp Boyé, MD, and colleagues from Franz-Volhard Clinic in Berlin, prefaced their study by saying that prophylactic placement of implantable cardioverter defibrillators (ICDs) in patients with chronic myocardial infarction (MI) has been shown to reduce mortality by decreasing life threatening ventricular arrhythmia.

The use of ICDs in this large patient population, however, is still limited by high costs and possible adverse events including inappropriate discharges and progression of heart failure, the authors noted.

Since the ventricular arrhythmia is related to infarct size and morphology, researchers tested the hypothesis that contrast-enhanced cardiovascular MRI (CE CMR) can quantify myocardial fibrosis and therefore be a valuable tool for a more accurate risk stratification of these patients.

Boyé and colleagues prospectively enrolled 52 patients with chronic MI and clinical indication for ICD therapy. They imaged patients on a 1.5T Siemens Avanto scanner to assess left ventricular function, LV end-diastolic volume and LV mass. Researchers assessed infarct morphology with a late gadolinium enhancement sequence.

They performed follow-up ICD readout after three months and then every six months for a mean of nearly three years.

The primary endpoint was the occurrence of an inappropriate discharge, anti-tachycardia pacing or death from cardiac cause. Ten patients experienced events: three inappropriate discharges, six -tachycardia pacing and one death. CE CMR of these patients revealed a higher relative infarct mass, as well as a higher degree of transmurality, defined as the percentage of transmurality in each scar, compared with the group with no events.

Researchers found no correlation between left ventricular function, LV end-diastolic volume, LV mass or total infarct mass between the two groups.

They concluded that only the degree of transmurality and the relative infarct mass were independent predictors of the events in this group of patients and that CE MRI can identify patients at a higher risk of these events.

“This additional information from CE CMR could lead to more precise risk stratification and might reduce adverse events and cost of ICD therapy in this patient population,” said Boyé, adding that larger trials are needed to confirm the finding.