Does CMR improve aetiological sub-phenotyping beyond echocardiography in patients with elevated LV filling pressure? A prospective registry study (PREFER-CMR)

OBJECTIVES: To evaluate the incremental diagnostic value and sub-phenotyping capability of Cardiovascular Magnetic Resonance (CMR) compared with Transthoracic Echocardiography (TTE) in patients with elevated left ventricular filling pressure (LVFP). DESIGN: Prospective registry study. [Results from ClinicalTrials.gov ID NCT05114785] SETTING: A single NHS hospital in the UK. MAIN OUTCOME MEASURES: The primary outcome was the rate of diagnostic discordance between TTE and CMR. Secondary outcomes included the characterisation of specific pathologies identified by CMR where TTE was normal, non-diagnostic or provided a non-specific diagnosis. RESULTS: CMR demonstrated diagnostic discordance with TTE in 74% (n=194) of cases. In patients with a normal TTE (n=54), CMR identified heart failure with preserved ejection fraction (HFpEF) in 46% (n=25) and ischaemic heart disease (IHD) in 19% (n=10). For non-diagnostic TTE cases (n=15), CMR detected HFpEF in 53.3% (n=8) and IHD in 26.7% (n=4). Among those with non-specific left ventricular hypertrophy on TTE (n=47), CMR revealed HFpEF in 45% (n=21) and hypertrophic cardiomyopathy in 34% (n=16). CONCLUSIONS: CMR markedly improves diagnostic precision and sub-phenotyping in patients with elevated LVFP, identifying key conditions like HFpEF, IHD and specific cardiomyopathies that TTE frequently misses. These findings highlight CMR's critical role as a complementary imaging tool for refining diagnoses and informing management strategies in cardiovascular conditions.