Study Underscores Need for Optimal RV Function Measures in PH

Researchers of a new study are highlighting the need for optimal objective approaches to determining right ventricular (RV) function, an established predictor of outcomes in patients with pulmonary hypertension (PH).

RV dysfunction has previously been linked to symptoms and mortality in PH, as well as in other conditions, and RV function plays an important role in disease risk and potentially in intensification of pulmonary arterial hypertension (PAH) treatment.

“While it is accepted that PAH disease progression and mortality risk are strongly associated with RV dysfunction, there remains uncertainty regarding the optimal means of assessing RV function,” explained the researchers in Pulmonary Circulation. “Currently, RV function in PH is most often assessed by echocardiogram objectively using TAPSE [tricuspid annular plane systolic excursion] or subjectively and classified as having mild, moderate, severe, or no RV dysfunction. Accurate measurement of TAPSE is angle‐dependent, leaving potential for underestimation, and not all studies have demonstrated reliability of this measure in PAH risk determination.”

Previous research shows that RV global longitudinal strain (RVGLS), which measures longitudinal shortening of RV deep muscle fibers through 2-dimensional echocardiography, is predictive of short-term mortality in patients with PH.

Assessing the utility of RV strain imaging, the group analyzed data from 2 cohorts—one retrospective and one prospective—from a single center, which gave conflicting findings, showing that measuring RV strain was a prognostic marker in the retrospective cohort of 83 patients with precapillary PH but not the validation cohort of 50 patients with PAH.

Compared with TAPSE, less negative RVGLS was marginally better at predicting death in the retrospective cohort of mixed patients, most of whom had PAH. However, the measure was not predictive of death or a combined morbidity and mortality outcome in the prospective cohort, contradicting the previous indications that the measure is a predictor of short-term PH progression and mortality. The previous research, cautioned the researchers, was typically retrospective in nature and not internally validated.

Within the retrospective cohort, the optimal RVGLS cut point was –12.7%, which showed good sensitivity and specificity, at about 75% each. The researchers noted that this is in line with previous literature. RVGLS and RV free wall strain (RVFWS) showed similar discrimination for mortality, although RVWFS showed better sensitivity for mortality than specificity.

“Based on existing literature and our current report, we suggest that either TAPSE or RV strain (RVGLS or RVFWS) would be appropriate methods for determining risk in a patient with PH,” detailed the researchers. “Yet, these parameters may remain abnormal in treated PAH patients and have limited prognostic value. Congruent with current guidelines, we support a multimodal assessment of risk in patients with PH and caution against overreliance on a single factor including non-invasive assessment of RV function.”

Differences in findings between the 2 cohorts may be explained by several factors, explained the researchers. Although the differences could be a result of different study populations—patients making up the prospective cohort mostly had Group 1 PH, whereas the retrospective cohort varied between PAH and Groups 3-5 PH—they believe it is more likely a result of underlying disease risk between the 2 groups. Overall, 1-year mortality was 16% in the retrospective cohort, significantly higher than the2% in the prospective cohort. The low mortality rate in the prospective cohort may have limited the ability to demonstrate prediction, explained the group.

Patients in the prospective cohort were slightly older and more likely than those in the retrospective cohort to be receiving PAH-targeted treatment at the time of echocardiography, suggesting these patients were more likely to have established PAH and not incident or early-stage PAH. Based on the finding, the researchers posed the question of whether effectively managing PAH can impact RV function of time according to RV strain measured.

Reference

Crossman L, Rajaram P, Hart C, et al. Evaluation of right ventricular strain in two separate cohorts with precapillary pulmonary hypertension. Pulm Circ. Published online February 14, 2023. doi:10.1002/pul2.12204