What is the clinical evidence from this study?

Study design: Observational. Population: Prior myocardial infarction and reduced left ventricular ejection fraction (n=995). Intervention: Selvester QRS scoring vs. Low vs Medium vs High QRS score. Primary outcome: Ventricular tachycardia or ventricular fibrillation (VT/VF) (HR 0.98, 95% CI 0.94-1.03, p=0.450).

June 9, 2013

ECG Quantification of Myocardial Scar and Risk Stratification in MADIT‐II

Key Result

In patients with prior myocardial infarction and severe left ventricular dysfunction, Selvester QRS score did not significantly predict the risk of ventricular tachycardia or fibrillation (HR 0.98).

Study Design

Type

Observational (n=995)

Blinding

Single-blind

Multicenter

Yes

Structured PICO

Does ECG quantification of myocardial scar using the Selvester QRS score predict risk for sudden cardiac death versus non-sudden cardiac death in patients with prior MI and LVEF ≤30%?

Population

995 adults from the MADIT-II trial with prior myocardial infarction (≥1 month before entry) and LVEF ≤30%, excluding NYHA class IV, who had ECGs of sufficient quality for QRS scoring.

Intervention

Implantable cardioverter-defibrillator (ICD) and Selvester QRS scoring (categorized as low 0-3, medium 4-7, high ≥8) to quantify myocardial infarction size.

Comparator

Conventional medical therapy (CMT) and comparison across QRS score strata.

Outcome

Episodes of VT or VF preceding an ICD shock or antitachycardia pacing (ATP)hard clinical

ECG quantification of myocardial scar using the Selvester QRS score did not add prognostic value for predicting sudden cardiac death or ventricular arrhythmias in the MADIT-II population with severe ischemic left ventricular dysfunction.

Main Result

Effect estimate: HR 0.98 (95% CI 0.94-1.03)

p-value: p=0.450

Limitations

Classification of mortality subtypes in the conventional medical therapy arm lacked arrhythmia monitoring, limiting certainty of cause of death.
Use of photocopied ECGs limited precision and led to the exclusion of 19% of the population due to poor quality.
Imbalance in right and left bundle branch block prevalence across the different QRS score groups.

Abstract

BACKGROUND: Low left ventricular ejection fraction (LVEF) increases risk for both sudden cardiac death (SCD) and for heart failure (HF) death; however, implantable cardioverter-defibrillators (ICDs) reduce the incidence of SCD, not HF death. Distinguishing individuals at risk for HF death (non-SCD) versus SCD could improve ICD patient selection. OBJECTIVE: This study evaluated whether electrocardiogram (ECG) quantification of myocardial infarction (MI) could discriminate risk for SCD versus non-SCD. METHODS: Selvester QRS scoring was performed on 995 MADIT-II trial subjects' ECGs to quantify MI size. MIs were categorized as small (0-3 QRS points), medium (4-7) or large (≥ 8). Mortality, SCD and non-SCD rates in the conventional medical therapy (CMT) arm and mortality and ventricular tachycardia/fibrillation (VT/VF) rates in the ICD arm were analyzed by QRS score group. Both arms were analyzed to determine ICD efficacy by QRS score group. RESULTS: In the CMT arm, mortality, SCD and non-SCD rates were similar across QRS score groups (P = 0.73, P = 0.92, and P = 0.77). The ICD arm showed similar rates of mortality (P = 0.17) and VT/VF (P = 0.24) across QRS score groups. ICD arm mortality was lower than CMT arm mortality across QRS score groups with greatest benefit in the large scar group. CONCLUSION: Recently, QRS score was shown to be predictive of VT/VF in the SCD-HeFT population consisting of both ischemic and nonischemic HF and having a maximum LVEF of 35% versus 30% for MADIT-II. Our study found that QRS score did not add prognostic value in the MADIT-II population exhibiting relatively more severe cardiac dysfunction.

Ask AI

Helpful

Bookmark

View Full Paper