ECG quantification of myocardial scar and risk stratification in MADIT-II

Area of Science:

• Cardiology
• Electrophysiology
• Medical Diagnostics

Background:

• Low left ventricular ejection fraction (LVEF) is a risk factor for sudden cardiac death (SCD) and heart failure (HF) mortality.
• Implantable cardioverter-defibrillators (ICDs) reduce SCD but not HF death.
• Improved patient selection for ICDs requires distinguishing risk for SCD versus non-SCD (HF death).

Purpose of the Study:

• To evaluate if electrocardiogram (ECG) quantification of myocardial infarction (MI) using Selvester QRS scoring can differentiate risk for SCD versus non-SCD.
• To assess the prognostic value of QRS scoring in predicting mortality and ventricular arrhythmias.

Main Methods:

• Selvester QRS scoring was performed on 995 MADIT-II trial participants' ECGs to quantify MI size.
• Participants were categorized into small, medium, or large MI groups based on QRS score.
• Mortality, SCD, and non-SCD rates were analyzed in the conventional medical therapy (CMT) arm, and mortality and ventricular tachycardia/fibrillation (VT/VF) rates in the ICD arm, stratified by QRS score group.

Main Results:

• In the CMT arm, mortality, SCD, and non-SCD rates were similar across QRS score groups.
• In the ICD arm, mortality and VT/VF rates were also similar across QRS score groups.
• ICD implantation reduced mortality compared to CMT across all QRS score groups, with the greatest benefit observed in patients with large myocardial scars.

Conclusions:

• QRS score did not provide additional prognostic value for predicting SCD or non-SCD in the MADIT-II population with severe cardiac dysfunction.
• Previous studies showed QRS score predictive of VT/VF in a broader HF population, but findings may differ in populations with more severe LVEF reduction.
• Selvester QRS scoring may not be a reliable tool for risk stratification in MADIT-II eligible patients for ICD therapy.