Author + information
- Michael J. Quon, MD and
- Louise Pilote, MD, MPH, PhD∗ ()
- ↵∗Division of General Internal Medicine, Department of Medicine, McGill University Health Centre, 1001 Decarie Boulevard, Room D05.5021, Montreal, Quebec H4A 3J1, Canada
The clinical benefit of anticoagulation in secondary atrial fibrillation (AF) remains unclear. In our study (1), we did not demonstrate benefit of oral anticoagulation (OAC) therapy in stroke reduction in patients who develop secondary AF associated with acute coronary syndromes, acute pulmonary disease, or sepsis. We agree with Mr. Um and colleagues that one should be cautious in assuming that OAC does not offer benefit in these patients. While awaiting more data on the incidence of recurrent AF in patients with acute medical illnesses and noncardiac surgery and a randomized clinical trial on the benefits of OAC, our study provides much needed information. Dr. Um and colleagues raise issues regarding: 1) ascertainment of AF prevalence; 2) residual confounding; and 3) estimates of benefit of OAC and recurrence of AF.
Dr. Um and colleagues are concerned with ascertainment of AF prevalence because of low sensitivity for detection of secondary AF using administrative databases. Our study was not aimed at measuring prevalence, which we agree would require high sensitivity, but at identifying patients with secondary AF; therefore high specificity rather than high sensitivity was privileged. To ensure true secondary AF (i.e., optimize specificity), our study criteria were designed to exclude both pre-existing primary AF and persistent AF. Unlike the retrospective study cited (2), we included only AF that was coded as a complication of the hospitalization and then additionally excluded patients who had received OAC in the prior year. We also excluded patients who had a previous hospital admission or physician visit with documented AF within the prior year. Thus we believe the patients included in our various cohorts had secondary AF, but we recognize we may not have identified all such patients.
The evidence for benefit of OAC in secondary AF associated with acute medical illness is limited in published reports and is further detailed in our study. Although residual confounding can always be cited to explain results in observational studies, the use of OAC in our study patients was associated with higher bleeding with little evidence of benefit on stroke prevention. The null findings may be more a problem of power than of confounding. The study by Fauchier and colleagues (3), which Dr. Um and colleagues quote, cannot be used as an example of benefit from OAC because this study included patients with primary AF. In fact, 551 of 2,009 (27.4%) of their study patients were reported to have permanent AF. It is unclear how this particular study specifically relates to determining possible benefit of OAC in patients with secondary AF.
Although our study was designed to look at stroke and bleeding risk, we look forward to the results of the ongoing multicenter study (AFOTS [Atrial Fibrillation Occurring Transiently With Stress]; NCT03221777) to determine rates of AF recurrence among patients who experienced transient AF following noncardiac surgery and medical illness. Indeed, little is known about the true risk of recurrence of AF in these patients. We support any further studies that can help define an optimal management strategy for secondary AF.
Please note: The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
- 2018 American College of Cardiology Foundation
- Quon M.,
- Behlouli H.,
- Pilote L.
- Cheng C.A.,
- Cheng C.G.,
- Lin H.C.,
- et al.