A registry-based cohort study including 72,660 Medicare patients with and without atrial fibrillation (AF) who underwent non-apical transcatheter aortic valve replacement (TAVR) from 2014 to 2016, has shown that, TAVR patients with new-onset AF have the highest rate of all-cause mortality (32%) compared to patients with pre-existing or no AF (23.3% and 12.8%, respectively). New-onset AF was also associated with an increased risk of bleeding, stroke and heart failure (HF) hospitalizations.
The results of study were reported in JACC: Cardiovascular intervention by Dr. Amgad Mentias (University of Iowa Carver College of Medicine, Iowa City). Out of the 72,660 TAVR patients included in the study, 40,149 (55.3%) were without AF, 29,563 (40.7%) had pre-existing AF, and 2,948 (4%) suffered from new-onset AF. The investigators used ICD-9 (until September 2015) and ICD-10 codes thereafter to classify the patient population. Overall incidence of new-onset AF was 6.8% with a steady decline during 3 years of follow-up. This decline was explained by the authors due to inclusion of low-risk patients who underwent TAVR. New-onset AF was defined as AF occurring during the admission or within 30 days after the TAVR procedure and pre-existing AF was defined as AF occurring in the preceding 3 years before TAVR admission. The primary outcome of the study was all-cause mortality and secondary outcomes included hospitalizations due to stroke, bleeding or heart failure. All-cause mortality occurred in 32% of patients with new-onset AF, while 23.3% of those with pre-existing AF and 12.8% patients without AF died. Further, after adjusting for patient characteristics, new-onset AF was linked to a higher risk of death from any cause compared to patients with pre-existing AF and patients without AF (compared with pre-existing AF, adjusted hazard ratio [aHR]: 1.35; 95% CI: 1.26 to 1.45; p < 0.001; compared with no AF, aHR: 2.06; 95% CI: 1.92 to 2.20; p < 0.0001). In regards to secondary outcomes, new onset AF was associated with an increased risk of bleeding (sHR: 1.66; 95% CI: 1.48 to 1.86; p < 0.01), stroke (sHR: 1.92; 95% CI: 1.63 to 2.26; p < 0.01), and HF admissions (sHR: 1.98; 95% CI: 1.81 to 2.16; p < 0.01) compared with pre-existing AF. Compared to those with no AF, patients with pre-existing AF had a significantly higher risk of bleeding (sHR: 1.36; 95% CI: 1.28 to 1.45; p < 0.0001) and HF hospitalization (sHR: 1.77; 95% CI: 1.67 to 1.86; p <0.0001).
TAVR is rapidly becoming an effective and safe therapeutic modality for patients suffering from severe symptomatic aortic stenosis (AS) and holds a class 1 recommendation for those with prohibitive/high surgical risk. Recently, results from the PARTNER3 and EVOLUT trials have advocated TAVR even in those with low surgical risk. Evidence from randomized clinical trials continues to support that TAVR is better than or as good as surgery in terms of strokes and all-cause mortality in a broad risk spectrum of patients. However, in clinical practice, there is an increasing concern surrounding cerebrovascular events following TAVR and it has been shown that pre-existing AF or new-onset AF after a TAVR leads to a four-fold increase in the risk of in-hospital and late strokes. In the present study of a large cohort of TAVR patients stratified by the presence or absence of AF, the authors report that despite of having a lower burden of comorbidities at baseline, patients with new-onset AF have a higher risk of death, stroke, bleeding and HF hospitalizations. The authors attribute this elevated risk to peri-operative injury, inflammation, oxidative stress, left atrial stretching and absence of negative atrial remodeling after the procedure. The mean age of study participants in the new-onset AF group was 83.8 years, which was higher than the other groups, which also may have affected results. Nevertheless, the current study highlights the need for optimal management of TAVR patients with new-onset AF while minimizing bleeding-related risk and cardiac remodeling.
The study has limitations, the first being the use of a 3-year look back window to identify patients with pre-existing AF, which may have misclassified those patients who had AF episodes prior to 3 years as having no AF. Second is confounding by unmeasured factors in an observational dataset. Third, a distinction between paroxysmal and permanent AF is not made in the analysis. Fourth, the authors did not have information about medication-intake, especially anti-coagulation which may have affected the results.