Prognostic Value of Feature-Tracking Right Ventricular Longitudinal Strain in Severe Functional Tricuspid Regurgitation: A Multicenter Study

Abstract

Objectives: This study sought to evaluate the prognostic value of cardiac magnetic resonance (CMR) feature-tracking-derived right ventricular (RV) free wall longitudinal strain (RVFWLS) in a large multicenter population of patients with severe functional tricuspid regurgitation.

Background: Tricuspid regurgitation imposes a volume overload on the RV that can lead to progressive RV dilation and dysfunction. Overt RV dysfunction is associated with poor prognosis and increased operative risk. Abnormalities of myocardial strain may provide the earliest evidence of ventricular dysfunction. CMR feature-tracking techniques now allow assessment of strain from routine cine images, without specialized pulse sequences. Whether abnormalities of RV strain measured using CMR feature tracking have prognostic value in patients with tricuspid regurgitation is unknown.

Methods: Consecutive patients with severe functional tricuspid regurgitation undergoing CMR at 4 U.S. medical centers were included in this study. Feature-tracking RVFWLS was calculated from 4-chamber cine views. The primary endpoint was all-cause death. Cox proportional hazards regression modeling was used to examine the independent association between RVFWLS and death. The incremental prognostic value of RVFWLS was assessed in nested models.

Results: Of the 544 patients in this study, 128 died during a median follow-up of 6 years. By Kaplan-Meier analysis, patients with RVFWLS ≥median (-16%) had significantly reduced event-free survival compared with those with RVFWLS <median (log-rank p < 0.001). By Cox multivariable regression modeling, RVFWLS was associated with increased risk-of-death after adjustment for clinical and imaging risk factors, including RV size and ejection fraction (hazard ratio: 1.14 per %; p < 0.001). Addition of RVFWLS in this model resulted in significant improvement in the global chi-square (31 to 78; p < 0.001).

Conclusions: CMR feature-tracking-derived RVFWLS is an independent predictor of mortality in patients with severe functional tricuspid regurgitation, incremental to common clinical and imaging risk factors.

Keywords: cardiac magnetic resonance; feature tracking; global longitudinal strain; mortality; prognosis; right ventricular function; tricuspid regurgitation.

Figure 1.. Measurement of RVFWLS using the Segment CMR package (Medviso AB, Lund, Sweden).

Endocardial right ventricular contours were manually traced in the 4 chamber cine view to derive RVFWLS.

Figure 2.. Relationship between RVFWLS and hazard of death (with 95% confidence intervals).

Hazard ratios are relative to those with median RVFWLS.

Figure 3.. Sequential nested Cox models for death.

A model based on clinical variables alone (Age, Gender, Diabetes, Hypertension) was significantly improved by addition of imaging variables (Pulmonary Hypertension, Left sided valve disease, LVEF, LGE, TAPSE, RVEDV, RVEF), and further significantly improved by adding RVFWLS.

Central Illustration.. Kaplan-Meier survival curves in patients with severe functional tricuspid regurgitation, stratified by RVFWLS above and below the median value.

Kaplan-Meier analysis showed significantly increased risk of death in those with RVFWLS=median (log-rank p<0.001).