ECG Increases AF Detection, but Not Anticoagulation, After Stroke

Erik Greb

November 24, 2020

Systematic ECG monitoring increased the in-hospital rate of atrial fibrillation (AF) detection among stroke survivors, in a new study.  

However, systematic ECG monitoring did not result in a higher rate of anticoagulation at 12 months, results showed, and did not affect cardiovascular outcomes at 12 months.

Dr Matthias Endres

"As our pragmatic approach in unselected stroke or transient ischemic attack [TIA] patients did not significantly increase anticoagulation rates at 12 months, we propose that additional ECG monitoring should focus on stroke patients at increased risk of atrial fibrillation," Matthias Endres, MD, director of the Department of Neurology with Experimental Neurology at Charité Medical University in Berlin, Germany, told Medscape Medical News.

"Detection of atrial fibrillation and subsequent initiation of anticoagulation remain important goals in the care of stroke patients," he said.

Endres presented his study at the European Stroke Organization-World Stroke Organization (ESO-WSO) Conference 2020.

Prospective Study

Evidence indicates that AF increases the risk of ischemic stroke as much as fivefold. Long-term anticoagulation has been recommended to reduce this risk. Although prolonged ECG monitoring increases the likelihood of detecting AF, it is uncertain whether this measure affects secondary prevention, the researchers note.

Endres and colleagues conducted a prospective study (Impact of Standardized Monitoring for Detection of Atrial Fibrillation in Ischemic Stroke — MonDAFIS) at 38 certified stroke units to investigate whether prolonged ECG monitoring improves the detection of AF, increases anticoagulation rates, and reduces cardiovascular endpoints in stroke survivors. They enrolled 3465 patients with stroke or TIA into the trial. Patients with known AF before stroke or with AF that had been detected before enrollment were excluded.

Investigators randomly assigned participants to systematic in-hospital Holter ECG monitoring for as long as 7 days or to standard of care, consisting of the usual diagnostic procedures performed in German certified stroke units.

The primary endpoint was the proportion of patients alive and on oral anticoagulation at 12 months after the index stroke. Secondary endpoints included the proportion of patients with newly detected AF and the number of patients with the combined vascular endpoint (recurrent stroke, myocardial infarction, major bleeds, and all-cause death) within 6, 12, and 24 months of the index stroke.

The study's follow-up period was 24 months. The median duration of ECG monitoring was 120.6 hours. The complete randomized dataset included 3431 patients, and the full analysis set included 2920 patients.

Baseline characteristics were well balanced between the two study groups. Participants' average age was 66 years, and 40% were female. Strokes tended to be mild. The median NIH Stroke Scale score was 2. Approximately 22% of patients received intravenous thrombolysis. Median length of hospital stay was 7 days in both groups. Cardiovascular risk factors were well balanced between the groups.

Improved Detection

The rate of AF detection was 4% in the control group and 5.8% in the intervention group a difference that was statistically significant. The rate of detection was higher in patients over age 65 years and among patients with stroke rather than TIA. Stroke severity and the duration of ECG monitoring did not affect the rate of AF detection, however.

However, the higher rate of AF detection did not translate into more patients on anticoagulation at 12 months. The rate of oral anticoagulation at that point was 11.8% in the control group and 13.7% in the intervention group, a difference that was not statistically significant.

Some patients received anticoagulation for diagnoses other than AF, such as patent foramen ovale. When the researchers examined the proportions of patients for whom anticoagulation was prescribed because of AF, they again found no significant difference between groups.

In addition, the rate of the combined vascular endpoint did not differ significantly between groups. There were 249 cardiovascular events in the control group compared with 232 in the intervention group.

Investigators did observe fewer all-cause deaths in the intervention group than in the control group, however, and this difference was statistically significant. Because the number of strokes did not differ between groups, it is unclear how the intervention might have reduced the mortality rate, said Endres. "The observed reduction in mortality in the intervention group needs further investigation."

The data also indicate the high awareness and diagnostic standard for AF detection at certified stroke units, he added.

These results will provide a basis for the group's future research. Endres and colleagues plan to analyze the contribution of excessive supraventricular ectopic activity and atrial runs to the development of AF and recurrent events.

"In addition, we are presently evaluating the data of the Berlin Atrial Fibrillation Registry that was designed to analyze oral anticoagulation prescription in patients with atrial fibrillation and acute ischemic stroke for up to 3 years," Endres said.

Monitoring All Patients

"This study adds important evidence to support the benefits of inpatient cardiac telemetry for all stroke patients, not just those who have a stroke of cryptogenic etiology," Lee H. Schwamm, MD, vice president of digital health virtual care at Mass General Brigham and Massachusetts General Hospital in Boston, told Medscape Medical News. "The limitations of the study are its lack of reported reasons as to why oral anticoagulation was not prescribed, since many factors besides presence of atrial fibrillation go into that decision."

For example, bleeding complications from oral anticoagulants may explain why some patients were not on these medications at 24 months, said Schwamm, who was not a part of the MonDAFIS study. Patients with a high risk of bleeding might have been treated with alternative methods such as left atrial appendage closure. Some patients may have been nonadherent, and for others, the recommendation for anticoagulation may not have been communicated effectively from the hospital to the outpatient physician.

"This study suggests that we should ensure continuous ECG monitoring in all confirmed ischemic stroke patients," said Schwamm. The results raise the question of whether postdischarge monitoring should be considered in a broader population of cases.

"It is important to note that finding post-stroke atrial fibrillation does not imply that it was the cause of the index stroke, but it still is a potent and modifiable risk factor for recurrent stroke and thus a crucial target for secondary prevention," Schwamm added.

The study was supported by an unrestricted grant from Bayer Vital. Endres reported receiving research funding from Bayer Vital. He has received honoraria or compensation for consulting or advisory activities from companies such as Amgen, BMS, Boehringer Ingelheim, and Daiichi Sankyo. Schwamm is a national co-primary investigator of Stroke AF, an investigator-initiated trial sponsored by Medtronic.

European Stroke Organisation-World Stroke Organization (ESO-WSO) Conference 2020: Presented November 8, 2020.

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