MI Scar Burden and ICD Implantation in Cardiomyopathy
Objective We sought to assess the impact of myocardial scar burden (MSB) on the association between implantable cardioverter defibrillator (ICD) implantation and mortality in patients with ischaemic cardiomyopathy (ICM) and left ventricular EF ≤40%. In addition, we sought to determine the impact of gender on survival benefit with ICD implantation.
Design Retrospective observational study.
Setting Single US tertiary care centre.
Patients Consecutive patients with significant ICM who underwent delayed hyperenhancement-MRI between 2002 and 2006.
Interventions ICD implantation.
Main outcome measures All-cause mortality and cardiac transplantation.
Results Follow-up of 450 consecutive patients, over a mean of 5.8 years, identified 186 deaths. Cox proportional hazard modelling was used to evaluate associations among MSB, gender and ICD with respect to all-cause death as the primary endpoint. ICDs were implanted in 163 (36%) patients. On multivariable analysis, Scar% (χ 28.21, p<0.001), Gender (χ 12.39, p=0.015) and ICD (χ 9.57, p=0.022) were independent predictors of mortality after adjusting for multiple parameters. An interaction between MSB×ICD (χ 9.47, p=0.009) demonstrated significant differential survival with ICD based on MSB severity. Additionally, Scar%×ICD×Gender (χ 6.18, p=0.048) suggested that men with larger MSB had significant survival benefit with ICD, but men with smaller MSB derived limited benefit with ICD implantation. However, the inverse relationship was found in women.
Conclusions MSB is a powerful independent predictor of mortality in patients with and without ICD implantation. In addition, MSB may predict gender-based significant differences in survival benefit from ICDs in patients with severe ICM.
Implantable cardioverter defibrillators (ICDs) have been shown to reduce mortality in patients with ischaemic cardiomyopathy (ICM) and significant LV systolic dysfunction (LVD). Currently, echocardiographically-assessed LVEF and New York Heart Association class are the only established criteria for ICD implantation for primary prevention. However, LVEF≤35% has been shown to be a non-specific criterion for ventricular tachycardia/ventricular fibrillation (VT/VF) risk, and previous studies have demonstrated that a significant proportion of patients who underwent ICD implantation did not experience life-threatening arrhythmias after up to 5 years of follow-up. Thus, improved risk stratification is needed to identify optimal candidates for ICD implantation.
Delayed hyperenhancement cardiac magnetic resonance (DHE-CMR) quantified myocardial scar burden (MSB) has been shown to correlate with VT/VF and has been shown to be a powerful predictor of mortality in patients with ICM. Hence, we hypothesised that DHE-CMR may enhance risk stratification in patients with severe ICM being considered for ICD implantation. We sought to determine how scar burden (SB) impacts the association between ICD implantation and mortality.
Abstract and Introduction
Abstract
Objective We sought to assess the impact of myocardial scar burden (MSB) on the association between implantable cardioverter defibrillator (ICD) implantation and mortality in patients with ischaemic cardiomyopathy (ICM) and left ventricular EF ≤40%. In addition, we sought to determine the impact of gender on survival benefit with ICD implantation.
Design Retrospective observational study.
Setting Single US tertiary care centre.
Patients Consecutive patients with significant ICM who underwent delayed hyperenhancement-MRI between 2002 and 2006.
Interventions ICD implantation.
Main outcome measures All-cause mortality and cardiac transplantation.
Results Follow-up of 450 consecutive patients, over a mean of 5.8 years, identified 186 deaths. Cox proportional hazard modelling was used to evaluate associations among MSB, gender and ICD with respect to all-cause death as the primary endpoint. ICDs were implanted in 163 (36%) patients. On multivariable analysis, Scar% (χ 28.21, p<0.001), Gender (χ 12.39, p=0.015) and ICD (χ 9.57, p=0.022) were independent predictors of mortality after adjusting for multiple parameters. An interaction between MSB×ICD (χ 9.47, p=0.009) demonstrated significant differential survival with ICD based on MSB severity. Additionally, Scar%×ICD×Gender (χ 6.18, p=0.048) suggested that men with larger MSB had significant survival benefit with ICD, but men with smaller MSB derived limited benefit with ICD implantation. However, the inverse relationship was found in women.
Conclusions MSB is a powerful independent predictor of mortality in patients with and without ICD implantation. In addition, MSB may predict gender-based significant differences in survival benefit from ICDs in patients with severe ICM.
Introduction
Implantable cardioverter defibrillators (ICDs) have been shown to reduce mortality in patients with ischaemic cardiomyopathy (ICM) and significant LV systolic dysfunction (LVD). Currently, echocardiographically-assessed LVEF and New York Heart Association class are the only established criteria for ICD implantation for primary prevention. However, LVEF≤35% has been shown to be a non-specific criterion for ventricular tachycardia/ventricular fibrillation (VT/VF) risk, and previous studies have demonstrated that a significant proportion of patients who underwent ICD implantation did not experience life-threatening arrhythmias after up to 5 years of follow-up. Thus, improved risk stratification is needed to identify optimal candidates for ICD implantation.
Delayed hyperenhancement cardiac magnetic resonance (DHE-CMR) quantified myocardial scar burden (MSB) has been shown to correlate with VT/VF and has been shown to be a powerful predictor of mortality in patients with ICM. Hence, we hypothesised that DHE-CMR may enhance risk stratification in patients with severe ICM being considered for ICD implantation. We sought to determine how scar burden (SB) impacts the association between ICD implantation and mortality.