USA: Episodes of atrial fibrillation (AF) lasting at least 5.5 hours are associated with a higher risk of ischemic stroke, particularly in the first few days, a study carried out in patients with cardiac implantable electronic devices (CIEDs) confirms. Further, the risk of stroke was most apparent in the first 1 to 5 days after the AF episode after which it waned away and then dissipated quickly.
The study, published in the journal JAMA Cardiology, supports AF being a causal risk factor than the idea of a risk marker and that paroxysmal atrial fibrillation poses a risk of stroke during and for a short time and the risk decreases rapidly.
Understanding the temporal association between atrial fibrillation and ischemic stroke is helpful for understanding the AF-stroke mechanism and treatment of paroxysmal AF. Daniel E. Singer, Department of Medicine, Massachusetts General Hospital, Boston, and colleagues, therefore, aimed to define the temporal association between episodes of AF and stroke in patients with cardiac implantable electronic devices in a case-crossover study.
The study included data from a large national electronic health record database. The database were linked with a single-vendor database of heart rhythm records of patients with CIEDs capable of continuous heart rhythm monitoring. It included patients with CIEDs who sustained an ischemic stroke who also had 120 days of continuous remote rhythm monitoring prestroke. Exposure included AF for 5.5 hours or more on any given day during days 1 to 30 vs days 91 to 120 prestroke.
Of 891 included patients, 575 (64.5%) were male, and the median age was 76 years.
The study yielded the following findings:
The vast majority of patients with stroke had either no AF meeting the threshold duration of 5.5 hours or more in both the case and control periods (76.5%) or AF of 5.5 hours or more in both periods (16.0%).
For those not meeting the 5.5-hour AF threshold in either period, there was no or very little AF throughout the 120-day prestroke.
A total of 66 patients had informative, discordant arrhythmic states, with 52 having AF of 5.5 hours or more in the case period vs 14 in the control period (odds ratio [OR], 3.71).
Stroke risk was increased most in days 1 to 5 following an AF episode (OR, 5.00).
AF greater than 23 hours on a given day was associated with the clearest increase in stroke risk (OR, 5.00).
The researchers concluded, "our findings are consistent with the traditional view that AF is directly and transiently associated with ischemic stroke. These results provide support for trials of time-delimited anticoagulation for patients with infrequent multihour episodes of AF and rigorous, continuous rhythm monitoring."
Reference:
Singer DE, Ziegler PD, Koehler JL, Sarkar S, Passman RS. Temporal Association Between Episodes of Atrial Fibrillation and Risk of Ischemic Stroke. JAMA Cardiol. Published online September 29, 2021. doi:10.1001/jamacardio.2021.3702