Heart’s Ventricular Mass on MRI May Predict Risk of Death in PAH, Study Says

The heart’s ventricular mass may be an early prognostic biomarker for predicting the risk of heart failure and death in people with pulmonary arterial hypertension (PAH), a recent study suggests.

The research, “Ventricular mass as a prognostic imaging biomarker in incident pulmonary arterial hypertension,” was published in the European Respiratory Journal.

Right heart failure is a common cause of death among people with PAH. Vessels that transport blood from the heart into the lungs — the pulmonary arteries — become narrowed, obstructing the passage of blood. As the heart needs to work harder to pump blood into the lungs, the right ventricle (lower chamber) becomes enlarged and weakened. As the heart’s function is progressively affected, it may result in heart failure.

Heart MRI, or cardiac magnetic resonance (CMR) imaging, is used to look at the heart’s right ventricle, and evidence suggests that the technique can give valuable cues for predicting the likelihood of heart failure and death.

Most studies on PAH patients have focused on the measurement of ventricular volumes, and how much blood is being pumped out of the right side of the heart to the lungs — a parameter called right ventricular ejection fraction (RVEF).

But in this study, a team at Johns Hopkins University, together with collaborators from other institutions, investigated the potential of a different kind of CMR prognostic marker. They looked at different metrics of left and right ventricular mass in 64 patients (mean age 57) who underwent CMR following right heart catheterization.

Among these patients, 42 had connective tissue disease-associated PAH (CTD-PAH), mostly with scleroderma related-PAH, and 22 were diagnosed with idiopathic PAH (IPAH).

Researchers analyzed the relationship between several right ventricular (RV) and left ventricular (LV) mass measures at the time of the surgical procedure, and subsequent mortality over a median follow-up period of 4.2 years.

Results showed that two of these measures, RVEDMI % predicted (RVEDMI stands for right ventricle end-diastolic mass index) and VMI (ratio of right ventricular mass to left ventricular mass), were significantly associated with mortality.

Each 10% increase in RVEDMI % predicted was associated with a 12% higher mortality. Similarly, for each 10% increase in VMI there was an 11% higher death rate. The magnitude of these correlations persisted after adjusting the results for age, sex, race, disease subtype, functional capacity, and other heart measures.

“Our results suggest that RV mass and VMI are candidate prognostic markers in incident PAH,” researchers wrote.

The study also suggests that RV hypertrophy (overgrowth) may not always be a positive body adaptation to PAH, as it is often considered. According to the data, there may be patients in whom  hypertrophy represents a harmful remodeling, such as dilation.

For these patients, “mass metrics might offer earlier prognostic insights than RV volumes or RVEF, which are indicators of dilatation and dysfunction,” the researchers stated.

Moreover, based on this and prior studies, it seems likely that coupling RV and LV metrics will increase the prognostic value of heart measurements for people with PAH.

The team emphasized that although promising, the findings should be interpreted with caution, as a small group of patients were studied, and there were relatively few with IPAH, limiting the ability to detect differences among disease subtypes.

Future studies are therefore needed to examine the prognostic value of mass metrics in larger groups of patients with different disease subtypes, and over time, the team stated.