CMR in Patients With Frequent Premature Ventricular Complexes
- In a cohort of 255 patients with frequent premature ventricular complexes (PVCs) and no known structural heart disease, CMR identified myocardial abnormalities in 35 patients (13.7%). The most common site of late gadolinium enhancement was the basal inferolateral segment.
- On multivariable analysis, predictors of adverse clinical outcomes included PVCs originating from the non-outflow tract left ventricle, baseline left bundle branch block, nonsustained VT, and presence of myocardial abnormality on CMR.
What is the diagnostic and prognostic utility of cardiac magnetic resonance (CMR) in patients with frequent premature ventricular complexes (PVCs) of unknown etiology?
This single-center, prospective cohort study included adults with frequent PVCs (≥5% in 24 hours on ambulatory electrocardiography). Exclusion criteria were pre-existing structural heart disease (such as hypertrophic cardiomyopathy or history of myocardial infarction) and severe left ventricular (LV) systolic dysfunction, with ejection fraction (EF) <30% on echocardiography. All patients underwent baseline CMR including late gadolinium enhancement (LGE) imaging. The primary composite outcome included all-cause mortality, nonfatal ventricular fibrillation (VF) or sustained ventricular tachycardia (VT) requiring intervention, and reduction in EF ≥10% compared to baseline.
A total of 255 patients (mean age 54.8 years, 46.7% male, 22.7% asymptomatic) were included. Mean baseline EF was 56.4%, and 13.7% of patients had baseline EF <50%. Median initial PVC burden was 16%, and 85.9% of patients had monomorphic PVCs. The most common PVC locations were the right ventricular outflow tract (49.0%) and the left ventricular outflow tract/aortomitral continuity (22.7%).
Myocardial abnormalities on CMR were present in 35 patients (13.7%), including 28 patients (11.0%) with LV LGE. Of the 23 patients who had LV LGE and monomorphic PVCs, 14 had PVC origins corresponding to areas of LGE. The most common site of LGE was the basal inferolateral segment (20 patients). LV LGE had an ischemic distribution in five patients. On multivariable analysis, myocardial abnormalities on CMR were associated with age ≥60 years, multifocal PVCs, and non-outflow tract LV PVC origin.
After a median follow-up of 36 months, 15 patients (5.9%) experienced the primary composite outcome (three deaths, three with sustained VT, and nine with reduction in EF ≥10%). The incidence of the composite outcome was significantly higher among patients with myocardial abnormalities on CMR compared to those without (20.0% vs. 3.6%, p < 0.001). On multivariable analysis, predictors of the composite outcome included PVCs originating from the non-outflow tract LV (hazard ratio [HR], 4.68), baseline left bundle branch block (HR, 14.35), nonsustained VT (HR, 3.71), and presence of myocardial abnormality on CMR (HR, 4.35).
In this cohort of patients with frequent PVCs and no known structural heart disease, CMR identified myocardial abnormalities in approximately one in seven patients. CMR abnormalities were associated with adverse clinical outcomes.
This study re-emphasizes the fact that CMR can be helpful in identifying structural heart disease, including subclinical ischemic heart disease, that is not evident on echocardiography. A limitation of the study is potential selection bias, as it was conducted at a tertiary referral center. Further research will be needed to determine how more advanced CMR techniques, such as T1 mapping, might be useful in this population.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Echocardiography/Ultrasound, Magnetic Resonance Imaging
Keywords: Arrhythmias, Cardiac, Bundle-Branch Block, Cardiomyopathy, Hypertrophic, Contrast Media, Diagnostic Imaging, Echocardiography, Electrocardiography, Ambulatory, Gadolinium, Heart Failure, Magnetic Resonance Imaging, Myocardial Infarction, Myocardial Ischemia, Stroke Volume, Tachycardia, Ventricular, Ventricular Fibrillation, Ventricular Premature Complexes
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