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).

Prospective registry study. [Results from ClinicalTrials.gov ID NCT05114785]

A single NHS hospital in the UK.

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.

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).

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.