The diagnostic role of cardiac magnetic resonance in the evaluation of a high volume of ventricular ectopy.

Background: The assessment and management of patients with a high volume of ventricular ectopic beats (VEBs) can be challenging. Cardiac Magnetic Resonance Imaging (CMR) is a robust imaging tool for the assessment of cardiac function, structure and tissue characterization. The value of performing CMR on patients with varying degrees of ventricular ectopy is not well studied. This study aimed to establish the prevalence of cardiac disease on CMR in patients referred with a history of high VEB burden.

Methods: A single-center retrospective observational study was conducted in a metropolitan tertiary hospital in Sydney, Australia. Adult patients who underwent CMR at 3 Tesla for the investigation of VEBs were included (n = 120 patients) from April 2023 – March 2025. Forty-six had available Holter monitor data and patient records.

The main independent variable was VEB burden, retrieved from Holter monitor and patient records. This was assessed as a continuous variable, as well as with a pre-defined cutoff of > 5% VEB. This was further stratified by the presence of ventricular arrhythmia (VA) (defined as runs of ≥ 3 VEBs on Holter monitor or stated ventricular tachycardia/ventricular fibrillation).

The main outcomes assessed were cardiac dimensions, function and the presence of late gadolinium enhancement (LGE) on CMR.

Results: The mean age was 59.6 years old; 59% of patients were male. The mean VEB burden was 7.4% (Range 0.0 - 37.0%), with a median of 3.2% (IQR 0.3% - 9.1%).

The mean left ventricular end diastolic volume was 161.9mL and was 158.1mL for those with ≤ 5% burden of VEBs compared to 167.1mL in those with > 5% burden. Left ventricular ejection fraction was 61% overall and remained unchanged when stratified by VEB burden (Table 1).

The mean VEB burden was 7.6% (95% CI 3.0% - 12.2%, SD 8.9%) and median 5.0% (IQR 1.0% - 12.0%) in patients with LGE; not significantly different when compared to a mean of 7.2% (3.4% - 11.1%, SD 10.0%) and median 3.0% (IQR 0.2% - 9.0%) in patients without LGE (Figure 1, Mann-Whitney U = 227.6, n1 = 29, n2 = 17, p = 0.67 two-tailed).

The proportion of patients with a large VEB burden was 8 in 17 (47%) for patients with LGE, not significantly different to 11 in 29 (38%) for patients without LGE, χ2 (2, N = 46) = 0.37, p = 0.54.

Twenty-eight patients (61%) had runs of ventricular arrhythmia; in this cohort there was no significant increase in prevalence of LGE (Table 2), χ2 (2, N = 46) = 1.07, p = 0.30.

Conclusion: In our series, there was little added value for the assessment of cardiac MRI for the assessment of VEBs. Larger multi-center studies are required to determine if CMR should be used for this indication.

Cardiac Dimensions and Ventricular Function Stratified by Ventricular Ectopy Burden.

Dimension	Overall		VEB ≤ 5%		VEB > 5%
	Mean	SD	Mean	SD	Mean	SD
Outflow Vessels & Atria
Aortic Root Size (mm)	33.02	4.40	31.80	3.57	34.78	4.97
Ascending Aortic Length (mm)	31.0	5.48	30.68	5.58	31.42	5.47
Ascending Aortic Width (mm)	30.48	5.56	30.18	5.81	30.80	5.55
Sinotubular Junction Size (mm)	27.50	3.50	26.92	3.11	28.33	3.94
MPA size (mm)	23.67	3.98	23.73	4.37	23.58	3.50
RPA size (mm)	16.93	5.12	17.00	6.10	16.83	3.41
LPA size (mm)	17.93	4.31	17.83	4.66	18.08	3.94
LA area (cm2)	26.54	6.80	26.49	7.53	26.61	5.91
RA area (cm2)	22.75	5.40	22.08	4.18	23.63	6.69
Left Ventricle
LVEDV (mL)	161.88	41.13	158.12	38.13	167.11	45.56
LVEF (%)	60.6	9.4	60.5	8.4	60.9	10.9
LVEDVi (mL/m2)	83.84	18.92	81.97	14.85	86.64	24.05
LV mass (g)	115.02	35.98	106.86	34.49	126.53	35.85
LV mass index (g/m2)	58.27	14.89	54.33	13.32	64.30	15.59
Right Ventricle
RVEDV (mL)	166.47	41.43	163.00	41.16	171.28	42.50
RVEF (%)	56.9	8.2	56.9	6.7	56.9	10.2
RVEDVi (mL/m2)	86.04	18.43	84.43	16.37	88.44	21.49

Note. MPA = main pulmonary artery, RPA = right pulmonary artery, LPA = left pulmonary artery, LA = left atrial, RA = right atrial, LVEDV = left ventricular end-diastolic volume, LVEF = left ventricular ejection fraction, LVEDVi = left ventricular end-diastolic volume index, LV = left ventricle, RVEDV = right ventricular end-diastolic volume, RVEF = right ventricular ejection fraction, RVEDVi = right ventricular end-diastolic volume index.  Cross-tabulation Between Presence of LGE and Ventricular Arrhythmia.

	LGE	No LGE	Total
Ventricular Arrhythmia	12	16	28
No Ventricular Arrhythmia	5	13	8
Total	17	29	46

Note. χ2 = 1.07, p</span> = 0.30. LGE = late gadolinium enhancement Note. N = 46. There was no significant difference in VEB burden between the 29 patients without LGE on CMR with a median VEB burden of 3.0% (Range 0.0-37.0%, IQR 0.2% - 9.0%) compared to the 17 patients with LGE on CMR with a median VEB burden of 5.0% (Range 0.0-32.0%, IQR 1.0 - 12.0%). p = 0.67. VEB = ventricular ectopic beat; LGE = late gadolinium enhancement; CMR = cardiac magnetic resonance imaging.