New data from a Cleveland Clinic-led research team highlight the importance of right ventricular (RV) function in intermediate-risk patients undergoing transcatheter aortic valve replacement and could help point the way toward a more personalized therapeutic approach.
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Findings from a substudy of the multicenter PARTNER 2A trial, published May 8, 2018, in the European Heart Journal, suggest that worsening RV function is significantly more common following surgical aortic valve replacement (SAVR) than following transcatheter aortic valve replacement (TAVR). But regardless of procedure type, worsening RV function predicts greater risk for all-cause mortality and cardiovascular death, the findings show.
The original PARTNER 2A trial, for which Cleveland Clinic served as the core echocardiography lab, had demonstrated that among 2,032 intermediate-risk patients with aortic stenosis, TAVR was similar to SAVR with respect to the primary end point of death or disabling stroke (see Consult QD coverage of the trial here).
Now some PARTNER 2A investigators have drilled down into the study data to answer a question for which prior observational data had offered mixed signals: Is RV worsening associated with worse outcome following TAVR, as it is for SAVR?
“A major strength of this analysis is that it involves randomized patients,” says Cleveland Clinic cardiologist Paul Cremer, MD, lead author of the new analysis.
The substudy included all 1,376 PARTNER 2A patients who had core lab echocardiograms taken at baseline and at 30 days.
Of the 744 patients randomized to TAVR, 8.3 percent developed worsening RV function, defined as a decline by at least one grade from baseline to 30 days, compared with 24.7 percent of the 632 patients randomized to SAVR. This difference was highly significant, with an odds ratio (OR) of 3.61 (95% CI, 2.63-4.95). The association was maintained in a multivariate model, with an OR of 4.05 (95% CI, 2.55-6.44) for SAVR versus TAVR.
This is a new finding, Dr. Cremer notes. “We know that RV function may be worse immediately after SAVR because of the need for cardiopulmonary bypass and ischemic time with surgery, which can cause RV dysfunction,” he explains. “That’s something we see commonly soon after surgery. But here we looked at RV function after 30 days and outcomes out to two years.”
Interestingly, whereas baseline RV dilation was not associated with worsening RV post-procedure in those who underwent TAVR, it was in those who underwent SAVR (OR = 2.77; 95% CI, 1.35-5.68). In contrast, in patients who underwent TAVR, having baseline tricuspid regurgitation that was more than mild was associated with worsening RV function (OR = 5.33; 95% CI, 1.46-19.39), whereas in patients who underwent SAVR, there was no significant association with tricuspid regurgitation.
In any case, regardless of baseline status or AVR procedure type, patients with worsening RV function at 30 days had higher rates of overall mortality (hazard ratio [HR] =1.98; 95% CI, 1.40-2.79) and cardiovascular death (HR = 2.11; 95% CI, 1.22-3.66). The association with all-cause death remained significant after adjustments for various clinical and echocardiographic variables.
“The message is that once you have worsening RV function, it really doesn’t matter whether you had a TAVR or SAVR — your outcome is going to be worse,” Dr. Cremer says.
There was even a “dose response” relationship, he notes. After adjustments for baseline clinical and echocardiographic parameters, patients who developed moderate or severe RV dysfunction post-procedure after having normal baseline RV function had an even worse prognosis than those who maintained mild baseline RV dysfunction both at baseline and following valve replacement.
These findings all strongly suggest that cardiologists should be paying more attention to the right ventricle than they currently do, Dr. Cremer believes.
“Clinicians really need to recognize RV worsening as a high-risk finding,” he advises. “In general, the right ventricle is certainly the neglected ventricle. The majority of these aortic stenosis patients at intermediate surgical risk have normal left ventricular function at baseline. So when we look at echoes after patients have had aortic valve replacement, it’s important to appreciate that the change in RV function matters. Importantly, even mild RV dysfunction after AVR portends a poor prognosis in patients who had normal RV function at baseline.”
Dr. Cremer and his Cleveland Clinic colleagues are now following up on another of this substudy’s new findings: the significance of tricuspid regurgitation as a potential risk factor for worse outcomes in patients undergoing TAVR.
“I would stop short of making hard-and-fast recommendations without further studies, but the data suggest that — all other things being equal — if a patient has a dilated RV but not much tricuspid regurgitation, you might favor TAVR, whereas if the patient has a lot of tricuspid regurgitation, you might favor surgery.”
He adds that the findings raise the question of whether medical, surgical or percutaneous treatment of concomitant tricuspid regurgitation can preserve RV function. “This analysis suggests we should perhaps pay more attention to tricuspid regurgitation as well in patients with severe aortic stenosis. That’s what prompted us to look at this more closely in another substudy of PARTNER 2A.”
Those findings are undergoing final analysis prior to submission for publication.