November 16, 2020
3 min read
Verma S, et al. LBS.06: To screen or not to screen, and then what? Studies of detection and treatment of AF. Presented at: American Heart Association Scientific Sessions; Nov. 13-17, 2020 (virtual meeting).
Freedman reports he has financial ties with Alivecor, Bayer, Bristol Myers-Squibb/Pfizer, Daiichi Sankyo and Omron. Verma reports he received honoraria from Amgen, AstraZeneca, Bayer, Boehringer Ingelheim/Eli Lilly, EOCI, HLS Therapeutics, Janssen, Merck, Novartis, Novo Nordisk, Sanofi, Sun Pharma and Toronto Knowledge Translation Working Group and received research grants from Amgen, Boehringer Ingelheim/Eli Lilly, Bristol-Myers Squibb and HLS Therapeutics.
Continuous rhythm monitoring yielded significant undetected atrial fibrillation or flutter in a cohort of patients who had cardiac surgery, according to findings presented at the virtual American Heart Association Scientific Sessions.
Subodh Verma, MD, PhD, a cardiac surgeon at St. Michael’s Hospital in Toronto, said during a presentation that early postoperative AF (POAF) may occur in as many as half of patients within 3 to 5 days of surgery, but that the natural history of and risk factors for POAF after cardiac surgery are poorly defined.
Moreover, he said, clinicians have no guidelines and few datasets to reference in managing this risk. “The observation period in most studies has been limited to the hospitalization period,” he said.
For the SEARCH-AF trial, the researchers analyzed whether enhanced cardiac rhythm monitoring with an adhesive, continuous monitoring device results in higher rates of atrial fibrillation or atrial flutter during the subacute, postdischarge period of cardiac surgery patients who are at risk for stroke and developing postoperative atrial arrhythmias.
Working from the hypothesis that this continuous monitoring strategy would improve on usual care in detecting AF or atrial flutter within 30 days, the researchers randomly assigned 163 patients to enhanced cardiac rhythm monitoring using the SEEQ (Medtronic) or CardioSTAT (Icentia Inc) devices, and 173 patients to usual care, which specified monitoring at clinician discretion.
Eligible participants had undergone isolated CABG or valve replacement or repair with or without CABG and were in sinus rhythm at the time of randomization. In addition, clinicians had no intent to initiate oral anticoagulants upon discharge. Eligible participants had a CHA2DS2-VASc score of 4 or greater with other possible risk factors of COPD, sleep apnea, estimated glomerular filtration rate < 60 mL/min/1.73m2, mild left atrial dilatation and BMI 30 kg/m2 or greater.
Baseline characteristics were well balanced across the two study groups, according to Verma. The mean age was 67 years and 22% were women.
The primary endpoint was cumulative AF/atrial flutter duration of 6 minutes or greater, or documentation of AF/atrial flutter by a 12-lead ECG.
Results showed that 19.6% of participants in the study group and 1.7% of controls reached the primary endpoint, for an absolute rate difference of 17.9% (P < .001; number needed to screen = 6; 95% CI, 4-9). Verma noted that detection of AF/atrial flutter was “markedly enhanced” by the continuous monitoring device, and that the difference was “highly statistically significant.”
Cumulative AF/atrial flutter burden of longer than 6 hours was 8.6% higher in the continuous monitoring group (95% CI, 4.3-12.9). Similarly, cumulative AF/atrial flutter burden of longer than 24 hours was 3.1% higher in the study group compared with controls (95% CI, 0.4-5.7).
The effect of continuous monitoring was observed regardless of whether patients had isolated CABG or no CABG and was not impacted by age or CHA2DS2-VASc score.
“In patients who have undergone cardiac surgery and have an elevated risk of stroke with no history of preoperative or predischarge AF, a strategy of continuous rhythm monitoring unveiled a significant persistent burden of unrecognized and potentially actionable AF,” Verma concluded. “POAF after cardiac surgery is not confined to the hospitalization period per se.”
Verma added that while incidence of POAF decreased over the 4 weeks of monitoring, it was much higher than findings observed for such an outcome in previous datasets. “The rates of oral anticoagulation were lower than the rates of detected AF,” he said.
In a discussion after the presentation, Ben Freedman, PhD, MBBS, deputy director of cardiovascular research strategy at the Heart Research Institute at the University of Sydney, raised questions whether a screening or monitoring program of some kind can detect or prevent AF. He noted that a program like the one used in SEARCH-AF, which sampled “millions of seconds” of time from any given patient, can lead to a “greater yield” of data.
“If you look, you find more AF than if you don’t look,” he said.