Risk Stratification After Acute Myocardial Infarction With Cardiac MRI

Risk Stratification for Sudden Cardiac Death After Acute Myocardial Infarction by Measuring Left Ventricular Volume Scar 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

Inclusion Criteria:

• Evidence of AMI either ST segment elevation or Non-ST segment elevation MI by biomarkers of cardiac injury and symptoms. Cut-off for creatine phosphokinase (CPK) >2 times and troponin >3 times the upper limit for the lab. Only Patients who undergo coronary revascularization (PCI, CABG) will be enrolled.
• LVEF < 45%. (Based on 10 points SD in echo measurements for LVEF)
• NYHA functional class I-III
• Patients aged 18 or above, both genders.

Exclusion Criteria:

• Patients with spontaneous or induced sustained ventricular tachycardia after 48-72 hours. (30 beats or more at 120 bpm or greater)
• Absolute contraindications to undergo CMRI (Renal failure with GFR<30% or ICD/PPM)
• Antiarrhythmic medications for ventricular arrhythmias (other than beta-blockers)
• Severe non-ischemic cardiac pathology. (e.g., ARVD, HCM, severe, restrictive cardiomyopathies (amiloydosis/sarcoidosis). We are aware that non-ischemic and ischemic cardiomyopathy may co-exist. However, these cardiomyopathies convey further arrhythmic risk and diffuse LV impairment.
• Unwilling or unable to provide informed consent
• Life expectancy less than 1 year.
• Current drug or alcohol abuse.
• Pregnancy
• Claustrophobia
• Patients who are enrolled in other trials with a treatment arm. (Patients enrolled in diagnostic trials can be included).
• Difficulty to attend the follow-up schedule due to a history of medical noncompliance, living a distance from the study center, or anticipated nonresidence in the area for the length of time required for follow-up.