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CMR in Idiopathic Premature Ventricular Contractions
Study Questions:
What is the prevalence and prognostic significance of myocardial abnormalities identified by cardiac magnetic resonance (CMR) imaging in patients with apparently idiopathic premature ventricular contractions (PVCs)?
Methods:
There were 518 patients with frequent (>1,000/24 hours) PVCs and negative routine diagnostic workup. Patients underwent a CMR protocol comprehensive of late gadolinium enhancement (LGE) imaging for detection of necrosis/fibrosis. The study endpoint was a composite of sudden cardiac death (SCD), resuscitated cardiac arrest, and nonfatal episodes of ventricular fibrillation or sustained ventricular tachycardia requiring appropriate implantable cardioverter-defibrillator therapy.
Results:
Myocardial abnormalities were found in 85 (16%) patients. Male gender (odds ratio [OR], 4.3), family history of SCD and/or cardiomyopathy (OR, 3.6), multifocal PVCs (OR, 11.1), as well as non–left bundle branch block-inferior axis morphology (OR, 14.1) were all significantly related to the presence of myocardial abnormalities on CMR. After a median follow-up of 67 months, the composite endpoint occurred in 26 (5%) patients. Subjects with myocardial abnormalities on CMR had a higher incidence of the composite outcome (29%) compared to those without (0.2%; p < 0.01).
Conclusions:
CMR can identify concealed myocardial abnormalities in 16% of patients with apparently idiopathic frequent PVCs. Presence of myocardial abnormalities on CMR predict worse clinical outcomes.
Perspective:
PVCs occurring in the setting of a structurally normal heart are generally thought of as benign, while PVCs in patients with structural heart disease may be associated with worse outcomes. The present study shows that a small but non-negligible number of patients with what is deemed idiopathic PVCs after examination with routine imaging may still have discoverable structural abnormalities on CMR and that those abnormalities may be a predictor of worse outcome. This is because CMR can better assess especially right ventricular volumes and function and provide myocardial tissue characterization. The study suggests that routine CMR may be indicated in patients with significant PVC burden (>1,000/24 hours), especially if their morphology is inconsistent with right ventricular outflow tract origin or is multifocal. Optimal risk stratification and management are unknown.
Clinical Topics: Arrhythmias and Clinical EP, Cardiovascular Care Team, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Magnetic Resonance Imaging
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiomyopathies, Death, Sudden, Cardiac, Defibrillators, Implantable, Diagnostic Imaging, Fibrosis, Gadolinium, Heart Failure, Magnetic Resonance Imaging, Risk Assessment, Secondary Prevention, Tachycardia, Ventricular, Ventricular Fibrillation, Ventricular Premature Complexes
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