Right Atrial Phasic Function in Heart Failure With Preserved and Reduced Ejection Fraction

Abstract

Objectives: This study researched right atrial (RA) deformation indexes and their association with all-cause mortality among subjects with or without heart failure (HF).

Background: Although left atrial dysfunction is well described in HF, patterns of RA dysfunction and their prognostic implications are unclear. Cardiac magnetic resonance (CMR) imaging can provide excellent visualization of the RA. We used CMR to characterize RA phasic function in HF and to assess its prognostic implications.

Methods: This study prospectively examined 608 adults without HF (n = 407), as well as adults with HF with a reduced ejection fraction (HFrEF) (n = 105) or with HF with a preserved ejection fraction (HFpEF) (n = 96). Phasic RA function was measured via volume measurements and feature-tracking methods to derive longitudinal strain. All-cause death was ascertained over a median follow-up of 38.9 months. Standardized hazard ratios (HRs) were computed via Cox regression.

Results: Measures of RA phasic function were more prominently impaired in subjects with HFrEF than those in subjects with HFpEF. In analyses that adjusted for demographic factors, HF status, left ventricular ejection fraction, right ventricular end-diastolic volume index, and right ventricular ejection fraction, RA reservoir strain (HR: 0.66; 95% confidence interval [CI]: 0.47 to 0.92; p = 0.0154), RA expansion index (HR: 0.53; 95% CI: 0.31 to 0.91; p = 0.0116), RA conduit strain (HR: 0.58; 95% CI: 0.40 to 0.84; p = 0.0039), and RA conduit strain rate (HR: 1.51; 95% CI: 1.02 to 2.220; p = 0.0373) independently predicted all-cause mortality. In contrast, RA booster pump function and RA volume index did not independently predict the risk of death.

Conclusions: Phasic RA function is predictive of the risk of all-cause death in a diverse group of subjects with and without HF. RA conduit and reservoir function are independent predictors of mortality.

Keywords: feature tracking; longitudinal strain; magnetic resonance imaging; right atrium.

Figure 1. Representative Example of Measures of RA Deformation Derived From Atrial Tissue Tracking From Cine SSFP-MRI Images

(A) The prescription ofendocardial and epicardial reference points for tissue tracking. (B) Tracking of atrial tissue, shown at a different phase of the cardiac cycle (see Online Video 1). (C and D) Representative plots of strain and strain rate, respectively, along with measures of reservoir, conduit, and booster pump function derived from strain and strain rate curves. Note that atrial diastasis was used as the reference length for all strain and/or strain rate measurements. RA = right atrial; MRI = magnetic resonance images; SR-A = late diastolic (booster pump) atrial strain rate; SR-E = early diastolic (conduit) atrial strain rate; SSFP = steady state free precision.

Figure 2. Unadjusted Comparisons of Indexes of Phasic RA Function and Volumes

Unadjusted comparisons of indexes of phasic RA function and volumes among subjects without HF and those with HFrEF and HFpEF. Only significant differences are shown. ANOVA = analysis of variance; HF = heart failure; HFpEF = heart failure with preserved ejection fraction; HFrEF = heart failure with reduced ejection fraction; other abbreviation as in Figure 1

Figure 3. Adjusted Comparisons of Indexes of Phasic RA Function Between Subjects Without HF and Those With HFrEF and HFpEF

Comparisons of RA function and volume indexes among the three groups are presented after adjusting for age, sex, race/ethnicity, body mass index, systolic blood pressure, history ofchronic obstructive pulmonary disease, obstructive sleep apnea, current smoking, diabetes mellitus, right ventricular end-diastolic volume index and right ventricular ejection fraction, and pulmonary artery systolic pressure. Only significant differences are shown. ANCOVA = analysis of covariance; other abbreviations as in Figures 1 and 2.

Figure 4. Unadjusted Standardized HRs for Various Measures of RA Function

Unadjusted Standardized hazard ratios (HRs) for various measures of RA function, as predictors of mortality. CI = confidence intervals; other abbreviation as in Figure 1.

Figure 5. Standardized HRs for Various Measures of RA Function

Standardized HRs for various measures of RA function, as predictors of mortality in adjusted analyses. Models were adjusted for age, sex, race, Left ventricular ejection fraction, HF status, right ventricular end-diastolic volume index, and right ventricular ejection fraction. Abbreviations as in Figures 1 and 4.