Risk Stratification After Acute Myocardial Infarction With Cardiac MRI

Given the existing controversy regarding the appropriate determination time for placement of
implantable cardioverter-defibrillator (ICD) in patients at risk for sudden cardiac death
(SCD) following acute myocardial infarction (AMI), the modest ability of current criteria to
determine which patients will experience SCD, and the high impact of SCD to society, we
propose to conduct a prospective non-randomized observational study to determine:

- Whether quantification of left ventricular (LV) scar volume by cardiac magnetic
resonance (CMRI) prior to hospital discharge helps to predict which patients will have a
low ejection fraction (35%) at follow up and qualify for ICD implantation.

- Whether quantification of infarct scar volume by CMRI will help to identify which
patients will experience malignant ventricular arrhythmias and/or SCD at follow-up,
independent of the LV ejection fraction (LVEF).

Primary hypothesis:

Percentage of left ventricular scar volume as measured by CMRI post-MI strongly correlates
with LVEF at 40 days and 3 months.

Secondary hypothesis:

1. A volume of >40% of left ventricular scar measured by CMRI post-MI is predictive of LVEF
less than 35% at 40 days and at 3 months

2. Volume scar as measured by Cardiac magnetic resonance imaging after AMI (at day 5) is
predictive of clinical outcomes: SCD, total mortality, heart failure admission and
life-threatening malignant ventricular arrhythmias regardless of ejection fraction at 40
days and at 3 months.

Safety hypothesis:

ICDs will be implanted if patients meet criteria at 40 days post MI as per the current
American College of Cardiology (ACC) /American Heart Association (AHA) /Heart Rhythm Society
(HRS) 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities