Cardiac magnetic resonance imaging aids in differentiating dilated cardiomyopathy from the athlete's heart
Authors: Daems J J N , Adema B J , Kramarenko D , Van Diepen M A , Verwijs S M , Van Hattum J C , Poel E , Moen M H , Nelissen J L , Van Den Boogaard M , Van Der Crabben S N , Amin A S , Wilde A A M , Asselbergs F W , Jorstad H T 
Published: June 2024

Abstract

Background
Distinguishing mild dilated cardiomyopathy (DCM) from the athletes' heart is complex due to similar increases in indexed left ventricular end-diastolic volumes (LVEDVi) and decreases in ejection fractions (LVEF).

Purpose
To determine if Cardiac Magnetic Resonance (CMR) Imaging features can differentiate genotype- and CMR phenotype-positive DCM patients from LVEDVi and LVEF matched elite athletes.

Methods
We matched healthy, elite athletes from the ELITE cohort to genotype-positive DCM patients from the Amsterdam DCM registry with a 1:1 ratio. Selection criteria for DCM were LVEDVi exceeding the sex-specific upper limit of normal or reduced LVEF ≥ 40%. Matching was based on sex, LVEDVi, and LVEF using the smallest propensity score distance. Athletes with cardiovascular disease or non-hinge-point (non-HP) late gadolinium enhancement (LGE) were excluded. DCM patients with a (likely) pathogenic variant with non-DCM phenotypes (ARVC, HCM) were excluded. A multivariate backward elimination logistic regression model (1500 bootstraps) was used to differentiate DCM from the athlete’s heart, validated by sensitivity/specificity and area under the curve (AUC) analysis.

Results
We included 137 DCM patients (54.7% female, primary (likely) pathogenic variant: PLN 38.7%; TTN 23.4%; LMNA 7.3%, MYH7 6.6%; FLNC 5.8%, other 18.2%) and matched these to 137 elite athletes (51.1% female). DCM patients were older than elite athletes (41.2 years ±15.2 vs 27.9 years ±7.9, p &lt; .001). Despite matching, DCM patients had a lower LVEF (51.3% [47.0, 55.7] vs 53.3% [50.8, 56.0], p = .002) and LVEDVi (101.6 ml/m2 [90.2, 116.0] vs 107.9 ml/m2 [97.6, 120.0], p &lt; .001) than athletes. DCM patients had larger max left atrial volumes (LAV) (37.0 ml/m2 [30.8, 45.6] vs 32.8 ml/m2 [27.0, 40.8], p &lt; .001) but smaller max right atrial volumes (RAV) (41.6 ml/m2 [33.2, 47.9] vs 55.7 ml/m2 [46.5, 66.2], p &lt; .001). DCM patients had lower indexed LV mass (LVMi) (43.8 g/m2 [26.3, 74.2] vs 50.5 g/m2 [25.2, 91.2], p &lt; .001. DCM patients less frequently showed HP-LGE than elite athletes (7% vs 45%, p &lt; .001); 33% of DCM patients had non-HP LGE. The multivariate logistic regression model including age, sex, LVEDV, LVM, HP-LGE, max LAV and RAV, had an AUC of 0.966 (95% CI 0.947-0.986) with a sensitivity of 86% and a specificity of 96%. After excluding DCM patients with non-HP LGE and rematching, we retained 88 DCM patients and 88 elite athletes with similar LVEF (51.7% [47.9, 56.1] vs 52.5% [50.1, 55.9], p = 0.483) and LVEDVi (102.2 ml/m2 [90.1, 117.2] vs 108.0 ml/m2 [95.4, 121.4], p = 0.122). A multivariate logistic regression model including age, sex, LVEDV, LVM, max LAV and RAV, had an AUC of 0.936 (95% CI 0.890-0.967) with a sensitivity of 79% and a specificity of 95%.

Conclusion
Our findings highlight a limited number of parameters, easily obtained with CMR Imaging, which can differentiate between DCM and the athlete’s heart, with an excellent AUC in internal validation.