Abstract 210: Association between Paroxysmal Supraventricular Tachycardia and Ischemic Stroke in Patients Without Atrial Fibrillation

Abstract

Introduction: Paroxysmal supraventricular tachycardia (PSVT) is viewed as a benign heart-rhythm disorder. However, recent studies suggest that atrial dysrhythmias other than atrial fibrillation/flutter (AF) may signify an increased stroke risk. Hypothesis: PSVT is associated with subsequent ischemic stroke in patients without documented AF. Methods: We obtained inpatient and outpatient claims data from 2010-2011 in a 5% sample of Medicare beneficiaries ≥66 years of age. We included only patients with a pacemaker or defibrillator, since such patients often undergo interrogation of heart rhythm. Patients with AF or stroke before or at the time of device implantation were excluded. Our predictor variable was PSVT. The primary outcome was ischemic stroke and the secondary outcome was embolic stroke. All diagnoses were ascertained from ICD-9-CM codes using previously validated algorithms. We used Kaplan-Meier survival analysis and the log-rank test to compare outcomes in patients with and without PSVT, which was modeled as a time-varying covariate. Patients were censored at the time of incident AF, stroke, death, or on December 31, 2011. Cox proportional hazards analysis was used to assess the relationship between PSVT and stroke while adjusting for demographic characteristics and vascular risk factors. Results: Among 42,152 eligible patients with a median 1.8 years of follow-up, 2,245 (5.3%) had PSVT and 1,007 (2.4%) developed a stroke. The incidence of stroke after a PSVT diagnosis (2.17% per year; 95% confidence interval [CI], 1.45-3.24%) was significantly higher than in patients without PSVT (0.95% per year; 95% CI, 0.87-1.03%; P < 0.001). After adjustment for demographic characteristics and vascular risk factors, PSVT was associated with a higher hazard of stroke (hazard ratio [HR], 2.0; 95% CI, 1.3-3.0). This association appeared stronger for embolic stroke (HR, 3.6; 95% CI, 1.1-11.8). Conclusions: In Medicare beneficiaries with implantable pacemakers or defibrillators, PSVT was associated with ischemic stroke, especially embolic stroke, in the absence of documented AF. These results build on recent findings that disturbances of atrial rhythm and function other than AF may be a previously unrecognized stroke risk factor.