Transcatheter aortic valve replacement (TAVR) is still a safe, effective treatment option when patients with severe aortic stenosis (AS) present with a very low gradient, according to new research published in Frontiers in Cardiovascular Medicine.[1]
The study’s authors noted that few TAVR studies in recent years have focused on patients with a very low baseline gradient.
“Studies of ‘low-flow, low-gradient’ severe aortic stenosis have mainly included patients with a mean gradient of >25 mmHg,” wrote first author Faisal Rahman, BMBCh, an interventional cardiologist with Johns Hopkins Medicine, and colleagues. “Thus, patients with severe AS and a mean gradient of ≤25 mmHg is not a well-studied population with very limited data characterizing the phenotype and outcomes. This group may represent a distinct population of very low-gradient severe AS patients at even higher risk of adverse outcomes, possibly due to more advanced disease, worse left ventricular systolic and/or diastolic function, a systemic low-flow state, or a longer preceding duration of physical debilitation, and therefore may not benefit from aortic valve replacement.”
Rahman et al. performed a retrospective study of more than 1,000 TAVR patients who were treated at a single U.S. facility from January 2011 to December 2020. All underwent a commercial TAVR procedure, meaning patients participating in research studies were excluded. A multidisciplinary heart team made up of at least three interventional cardiologists and two cardiac surgeons diagnosed each patient and made the decision to perform TAVR. Patients were evaluated at baseline, after one month and after one year. Patients were asked to complete a Kansas City Cardiomyopathy Questionnaire (KCCQ-12) during all follow-up appointments to examine their quality of life.
Patients were placed into three groups based on their resting aortic mean transvalvular gradient, as determined by transthoracic echocardiography. A high gradient was defined as ≥40 mmHg, a low gradient was defined as 26-39 mmHg and a very low gradient was defined as ≤25 mmHg.
Overall, 57% of patients presented with a high gradient, 35% presented with a low gradient and 8% presented with a very low gradient. Patients with a very low gradient were more likely to present with a comorbidity such as atrial fibrillation, moderate mitral regurgitation and severe mitral regurgitation. These patients also were more symptomatic when presenting for TAVR than patients in the other groups.
After one year, the study’s primary outcome—a composite of all-cause death, a KCCQ-12 score lower than 45 or a decrease in KCCQ-12 score of 10 or more—was seen more in patients with a very low gradient (46.7%) than patients with a high gradient (23.1%) or low gradient (29.9%). However, the team emphasized, this appeared to be due to those higher rates of comorbidities. When making an adjustments for baseline characteristics, there was no longer a significant different between patient groups.
The authors also noted that “most patients” experienced a significant improvement in their KCCQ-12 score, both after 30 days and after one year. There was no difference in improvement between the groups, which suggests patients with a very low gradient can expect results comparable to patients with a low or high gradient.
“Nearly all patients with very-low-gradient severe AS who underwent TAVR had marked improvement in symptoms,” the authors concluded. “Our results suggest that severe symptomatic AS patients benefit from TAVR regardless of baseline mean gradient, though very-low-gradient patients primarily benefit in terms of symptomatic improvement rather than increased survival.”
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