A new study suggests that postprocedural right ventricular-to-pulmonary artery (RV-PA) uncoupling is an independent predictor of long-term mortality in patients undergoing transcatheter aortic valve replacement (TAVR). Writing in the July 10 issue of JACC: Cardiovascular Interventions, the study finds that among patients with postprocedural uncoupling, subjects with severe uncoupling demonstrated an excess mortality risk. Furthermore, the normalization of RV-PA coupling after TAVR indicated better outcomes, whereas either persistent or new-onset uncoupling was related to an increased risk of mortality. “In the present study, more than one-half of TAVR candidates had RV-PA uncoupling, with one-fourth of them showing severe uncoupling,” finds the study, which was published Monday online. “Consistently with previous data, we found that TAVR is associated with an improvement of RV-PA coupling, mainly related to a reduction of pulmonary pressures. Despite that, a considerable proportion of patients (up to 45%) had some degree of RV-PA coupling after the procedure.” Results of the analysis Detailed results obtained from the 900 patients featured in the retrospective cohort analysis revealed that 520 patients (58%) showed RV-PA uncoupling before TAVR, whereas post-TAVR RV-PA uncoupling was observed in 407 patients (45%). During a median follow-up of 40 months, 250 deaths (28%) occurred. Post-TAVR RV-PA uncoupling was independently associated with an increased risk of mortality (adjusted hazard ratio [HR]: 1.474; 95% confidence interval [CI]: 1.115-1.948; P=0.006), whereas pre-TAVR uncoupling was not. Among patients with post-TAVR RV-PA uncoupling, the presence of severe uncoupling identified a subgroup with the worst survival in a multivariable analysis (adjusted HR: 1.821; 95% CI: 1.173-2.827; P=0.008). Patients with RV-PA coupling recovery after TAVR showed similar outcomes as compared with patients with normal coupling. Conversely, the presence of either persistent or new-onset RV-PA uncoupling following TAVR was associated with an increased mortality risk. “In the present study, the presence of RV-PA uncoupling after TAVR was strongly associated with long-term survival,” the study says. “Notably, patients with recovered RV-PA coupling (33% of the population with baseline uncoupling) showed a favorable outcome, suggesting that preserved RV-PA coupling after TAVR is associated with a better prognosis, irrespective of the preprocedural coupling status. Conversely, patients with post-TAVR RV-PA uncoupling, whether the latter was persistent or new onset, showed a worse survival at four years, than the other groups.” Study methodology A total of 900 patients who underwent TAVR in two tertiary centers and with echocardiographic analysis performed within 3 months before and after the procedure were included in the retrospective cohort analysis. Baseline clinical characteristics of the Post-TAVR Normal Coupling cohort (n=493) include a mean age of 79.8±7.2 years and a female population of 250 (51%). The mean age of the Post-TAVR Uncoupling (n=407) cohort was 80.2±7 years with a female population of 207 (51%). Tricuspid annular plane systolic excursion (TAPSE) was measured on M-mode recordings of the lateral tricuspid annulus, whereas pulmonary artery systolic pressure (PASP) was calculated from the peak velocity of the tricuspid regurgitant jet. The ratio between TAPSE and PASP was then adopted as a non-invasive surrogate of RV-PA coupling. The research team then applied the following definitions: normal RV-PA coupling (TAPSE/PASP >0.55 mm/mm Hg) and RV-PA uncoupling (TAPSE/PASP >0.55 mm/mm Hg). Among patients with RV-PA uncoupling, TAPSE/PASP ≤0.32 mm/mm Hg was considered indicative of severe RV-PA uncoupling. The study endpoint was defined as all-cause mortality, with follow-up data complete for all patients. Editorial commentary In an editorial comment, Vincent Auffret, MD, PhD, and Guillaume Leurent, MD, pointed out that the study, as well as analysis of the PARTNER (Placement of Aortic Transcatheter Valve) 3 population, failed to demonstrate a meaningful association between pre-TAVR RV-PA coupling and late mortality and/or hospital readmission among TAVR recipients. “Differences in patients’ baseline risk profile and prevalence of cardiac damages may explain these discrepancies, especially as markers of higher stages of cardiac damages were predictors of new-onset uncoupling post-TAVR and were overall more frequent in patients with persistent uncoupling in the present study,” say the two commenters, both from the Université de Rennes in France. The editorialists went on to raise an issue with the TAPSE/PASP ratio, pointing out that while the study team chose their cutoffs on the basis of previous publications, the optimal statistical cutoff in their population from a prognostic standpoint was <0.38 mm/mm Hg. “Of note, using this cutoff, pre-TAVR RV-PA uncoupling was still not significantly associated with outcomes,” Auffret and Leurent commented. The authors also highlighted the debate surrounding echocardiographic evaluation of RV function, with recent studies highlighting the greater discriminative ability of newer indexes, such as RV free wall longitudinal strain and myocardial work, to diagnose RV dysfunction and predict outcomes. “Whether the inclusion of these indexes rather than TAPSE in the evaluation of RV-PA coupling provides further prognostic value is another intriguing area for future research,” added the editorialists. Sources: Meucci MC, Malara S, Butcher SC, et al. Evolution and Prognostic Impact of Right Ventricular–Pulmonary Artery Coupling After Transcatheter Aortic Valve Replacement. JACC Cardiovasc Interv. 2023;16:1612–1621. Auffret V, Leurent G. Right Ventricular–Pulmonary Artery Coupling After Transcatheter Aortic Valve Replacement: Closer to Optimal Prognosis Assessment? JACC Cardiovasc. Interv. 2023;16:1622–1625. Image Credit: ATRPhoto – stock.adobe.com