According to a new study, cardiac MRI can play an important complementary part in diagnosing heart failure (HF), which "presents a significant social and economic burden, and it is on the rise," researchers wrote in the European Heart Journal (2022; https://doi.org/10.1093/eurheartj/ehac207). As the authors noted, the underlying pathophysiology of HF is raised intracardiac filling pressures. "Identification of raised left ventricular filling pressure (LVFP) is the cornerstone of HF diagnosis," they wrote.
"Reference methods for LVFP assessment are invasive catheter-based methods. In routine clinical practice, right heart catheterization (RHC) is preferred for comprehensive invasive evaluation of cardiovascular hemodynamics. In the absence of lesions in the pulmonary venules, veins, left atrium, and mitral valve, the pulmonary capillary wedge pressure (PCWP), obtained by occluding the pulmonary artery, provides an accurate measurement of LVFP."
The researchers noted that non-invasive imaging is routinely used to estimate left ventricular filling pressure in heart failure, with cardiovascular magnetic resonance (CMR) emerging as an important imaging tool for sub-phenotyping heart failure.
The main benefit of CMR, according to the authors, is its enhanced precision in functional and volumetric assessment. The investigators also noted that there is no available CMR model that predicts LVFP, and whether such a CMR model will offer any prognostic advantages also remains unclear.
"Currently, LVFP cannot be estimated from CMR," wrote the researchers, who took on this study to investigate if cardiac MR can estimate left ventricular filling pressure in patients with suspected heart failure, and if CMR-modelled LVFP has prognostic power.
To do so, the research team studied 835 patients who received an invasive assessment and a heart MRI on the same day from the ASPIRE registry, a database of patients assessed at the Sheffield Pulmonary Vascular Disease Unit.
Suspected HF patients underwent RHC, CMR, and transthoracic echocardiography (TTE) (validation cohort only) within 24 hours of each other. Right heart catheterization-measured PCWP was used as a reference for LVFP. At follow-up, death was considered as the primary endpoint. Researchers enrolled 835 patients (mean age: 65 +/- 13 years, 40% male).
In the derivation cohort, two CMR metrics were associated with RHC PCWP:LV mass and left atrial volume. When applied to the validation cohort, the correlation coefficient between RHC PCWP and CMR-modelled PCWP was 0.55.
Cardiovascular magnetic resonance-modelled PCWP was superior to TTE in classifying patients as normal or raised filling pressures. Cardiovascular magnetic resonance-modelled PCWP was associated with an increased risk of death. At Kaplan-Meier analysis, CMR-modelled PCWP was comparable to RHC PCWP to predict survival at 7-year follow-up. Ultimately, the authors concluded that a physiological CMR model can estimate left ventricular filling pressure in patients with suspected heart failure, and CMR-modelled LVFP has a prognostic role.
"Patients with heart failure have raised pressures inside the heart," noted Pankaj Garg, MD, Assistant Professor in Cardiovascular Medicine at the University of East Anglia, and a co-author of the study. "Currently, we use echocardiography to diagnose raised pressures inside the heart."
Previous studies, however, have demonstrated that standard echocardiography is not sufficient for diagnosing raised pressures inside the heart, added Garg, who is also an honorary consultant radiologist at Norfolk and Norwich University Hospitals.
"Hence, the main motive of this study was to see if heart MRI could provide a complementary role to aid the diagnosis of heart failure," he noted. "We tested heart MRI against the reference method for diagnosing raised pressures inside the heart, which is an invasive study."
In terms of diagnosing heart failure, cardiac MRI fills a complementary role to echocardiography, he continued, noting that echocardiography is "a very versatile tool that could be used for screening." However, Garg said CMR will provide greater accuracy in patients for whom the diagnosis of heart failure remains unclear, and CMR can also be used for follow-up of patients after medical intervention.
Going forward, radiology and imaging teams can use a formula proposed by Garg and his co-authors of the study to predict left ventricular filling pressure.
"This simple equation uses two common metrics from heart MRI scans to predict the pressure inside the heart-left atrial volume and left ventricular mass," he stated, pointing radiology teams to an online cardiovascular magnetic resonance calculator designed to aid in this effort (https://cardiacmri.weebly.com/).
Mark McGraw is a contributing writer.