Clinical utility and prognostic value of right atrial function in severe tricuspid regurgitation: one more piece of the puzzle

Right Atrial Remodeling and Outcome in Patients with Secondary Tricuspid Regurgitation

BACKGROUND

In patients with secondary tricuspid regurgitation (STR), right atrial remodeling (RAR) is a proven marker of disease progression. However, the prognostic value of RAR, assessed by indexed right atrial volume (RAVi) and reservoir strain (RAS), remains to be clarified. Accordingly, the aim of our study is to investigate the association with outcome of RAR in patients with STR.

METHODS

We enrolled 397 patients (44% men, 72.7 ± 13 years old) with mild to severe STR. Complete two-dimensional and speckle-tracking echocardiography analysis of right atrial and right ventricular (RV) size and function were obtained in all patients. The primary end point was the composite of death from any cause and heart failure hospitalization.

RESULTS

After a median follow-up of 15 months (interquartile range, 6-23), the end point was reached by 158 patients (39%). Patients with RAS <13% and RAVi >48 mL/m2 had significantly lower survival rates compared to patients with RAS ≥13% and RAVi ≤48 mL/m2 (log-rank P < .001). On multivariable analysis, RAS <13% (hazard ratio, 2.11; 95% CI, 1.43-3.11; P < .001) and RAVi > 48 mL/m2 (hazard ratio, 1.49; 95% CI, 1.01-2.18; P = .04) remained associated with the combined end point, even after adjusting for RV free-wall longitudinal strain, significant chronic kidney disease, and New York Heart Association class. Secondary tricuspid regurgitation excess mortality increased exponentially with values of 18.2% and 51.3 mL/m2 for RAS and RAVi, respectively. In nested models, the addition of RAS and RAVi provided incremental prognostic value over clinical, conventional echocardiographic parameters of RV size and function and RV free-wall longitudinal strain.

CONCLUSIONS

In patients with STR, RAR was independently associated with mortality and heart failure hospitalization. Assessment of RAR could improve risk stratification of patients with STR, potentially identifying those who may benefit from optimization of medical therapy and a closer follow-up.

STREI: a new index of right heart function in isolated severe tricuspid regurgitation by speckle-tracking echocardiography

AIMS

Right ventricular (RV) performance determines clinical management in severe tricuspid regurgitation (TR). Right atrial (RA) function complements RV assessment in TR. This study aimed to design a novel index by speckle-tracking echocardiography (STREI index) integrating RA and RV strain information and to evaluate the clinical utility of combining RV and RA strain for prediction of cardiovascular (CV) outcomes.

METHODS AND RESULTS

Consecutive patients with at least (≥) severe TR evaluated in the Heart Valve Clinic (n = 300) were prospectively included. An additional independent TR cohort was included for external validation (n = 50). STREI index was developed with the formula: [2 ∗ RV-free wall longitudinal strain (RV-FWLS)] + reservoir RA strain (RASr). The composite endpoint included hospital admission due to heart failure and all-cause mortality. A total of 176 patients with ≥severe TR were finally included. STREI index identified a higher percentage of patients with RV dysfunction compared with conventional parameters. After a median follow-up of 2.2 years (interquartile range: 12-41 months), a total of 38% reached the composite endpoint. STREI values were predictors of outcomes independently of TR severity and RV dimensions. The combination of prognostic cut-off values of RASr (<10%) and RV-FWLS (>-20%) (STREI stratification) stratified four different groups of risk independently of TR severity, RV dimensions, and clinical status (adj HR per stratum 1.89 (1.4-2.34), P < 0.001). Pre-defined cut-off values achieved similar prognostic performance in the validation cohort (n = 50).

CONCLUSION

STREI index is a novel parameter of RV performance that independently predicts CV events. The combination of RA and RV strain stratifies better patients' risk, reflecting a broader effect of TR on right heart chambers.

Atrial secondary tricuspid regurgitation: pathophysiology, definition, diagnosis, and treatment

Atrial secondary tricuspid regurgitation (A-STR) is a distinct phenotype of secondary tricuspid regurgitation with predominant dilation of the right atrium and normal right and left ventricular function. Atrial secondary tricuspid regurgitation occurs most commonly in elderly women with atrial fibrillation and in heart failure with preserved ejection fraction in sinus rhythm. In A-STR, the main mechanism of leaflet malcoaptation is related to the presence of a significant dilation of the tricuspid annulus secondary to right atrial enlargement. In addition, there is an insufficient adaptive growth of tricuspid valve leaflets that become unable to cover the enlarged annular area. As opposed to the ventricular phenotype, in A-STR, the tricuspid valve leaflet tethering is typically trivial. The A-STR phenotype accounts for 10%-15% of clinically relevant tricuspid regurgitation and has better outcomes compared with the more prevalent ventricular phenotype. Recent data suggest that patients with A-STR may benefit from more aggressive rhythm control and timely valve interventions. However, little is mentioned in current guidelines on how to identify, evaluate, and manage these patients due to the lack of consistent evidence and variable definitions of this entity in recent investigations. This interdisciplinary expert opinion document focusing on A-STR is intended to help physicians understand this complex and rapidly evolving topic by reviewing its distinct pathophysiology, diagnosis, and multi-modality imaging characteristics. It first defines A-STR by proposing specific quantitative criteria for defining the atrial phenotype and for discriminating it from the ventricular phenotype, in order to facilitate standardization and consistency in research.

Association of right atrial strain and long-term outcome in severe secondary tricuspid regurgitation

OBJECTIVE

Severe secondary tricuspid regurgitation (STR) causes significant right atrial (RA) volume overload, resulting in structural and functional RA-remodelling. This study evaluated whether patients with severe STR and reduced RA function, as assessed by RA-reservoir-strain (RASr), show lower long-term prognosis.

METHODS

Consecutive patients, from a single centre, with first diagnosis of severe STR and RASr measure available, were included. Extensive echocardiographic analysis comprised measures of cardiac chamber size and function, assessed also by two-dimensional speckle-tracking strain analysis. Primary outcome was all-cause mortality, analysed from inclusion until death or last follow-up. The association of RASr with the outcome was evaluated by Cox regression analysis and Akaike information criterion.

RESULTS

A total of 586 patients with severe STR (age 68±13 years; 52% male) were included. Patients presented with mild right ventricular (RV) dilatation (end-diastolic area 13.8±6.5 cm2/m2) and dysfunction (free-wall strain 16.2±7.2%), and with moderate-to-severe RA dilatation (max area 15.0±5.3 cm2/m2); the median value of RASr was 13%. In the overall population, 10-year overall survival was low (40%, 349 deaths), and was significantly lower in patients with lower RASr (defined by the median value): 36% (195 deaths) for RASr ≤13% compared with 45% (154 deaths) for RASr >13% (log-rank p=0.016). With a median follow-up of 6.6 years, RASr was independently associated with all-cause mortality (HR per 5% RASr increase:0.928; 95% CI 0.864 to 0.996; p=0.038), providing additional value over relevant clinical and echocardiographic covariates (including RA size and RV function/size).

CONCLUSIONS

Patients with severe STR presented with significant RA remodelling, and lower RA function, as measured by RASr, was independently associated with all-cause mortality, potentially improving risk stratification in these patients.