(HealthDay News) – Subclinical atrial tachyarrhythmias, which occur in approximately 10% of patients in the first three months after pacemaker or defibrillator implantation, are associated with an increased risk of clinical atrial fibrillation, stroke, and systemic embolism, according to a study published in the January 12 issue of the New England Journal of Medicine.
Jeff S. Healey, M.D., of McMaster University in Hamilton, Canada, and colleagues investigated whether subclinical episodes of tachyarrhythmia (defined as atrial rate >190 beats per minute for more than six minutes), detected by an implanted pacemaker or defibrillator, were associated with an increased risk of ischemic stroke. Participants included 2,580 patients, aged 65 years or older, with hypertension and no history of atrial fibrillation. Patients were monitored for three months and the primary outcome of ischemic stroke or systemic embolism was assessed during a mean follow-up of 2.5 years.
The investigators found that subclinical atrial tachyarrhythmias were detected in 10.1 percent of patients by three months. These tachyarrhythmias were associated with a significantly increased risk of clinical atrial fibrillation (hazard ratio [HR], 5.56). They were also associated with a significantly increased risk of ischemic stroke or systemic embolism (HR, 2.49), which remained significant after adjusting for predictors of stroke (HR, 2.5). There was a 13 percent population-attributable risk of stroke or systemic embolism associated with subclinical atrial tachyarrhythmias.
“The occurrence of subclinical atrial tachyarrhythmias was associated with a significantly increased risk of a subsequent stroke,” the authors write.
Several authors disclosed financial ties to pharmaceutical, medical device, and medical technology companies, including St. Jude Medical, which funded the study.