BACKGROUND: Approximately 30% of ischemic strokes have an unknown cause. Increased atrial ectopy (AE) increases the risk of atrial fibrillation (AF), but the risk of stroke in patients with increased AE is unknown.

OBJECTIVES: This study aimed to examine whether increased AE and short atrial runs increase the risk of stroke beyond incident AF.

METHODS: Data were collected during a 15-year follow-up of the Copenhagen Holter Study cohort with 678 men and women between 55 and 75 years of age, with no earlier history of cardiovascular disease, stroke, or AF. Study subjects underwent 48-h ambulatory electrocardiography, fasting blood tests, and clinical examination. Excessive supraventricular ectopic activity (ESVEA) was defined as the presence of either ≥30 premature atrial contractions (PACs)/hour daily or any runs of ≥20 PACs.

RESULTS: Ninety-nine subjects (15%) demonstrated ESVEA. After adjusting for baseline risk factors, ESVEA was associated with ischemic stroke when censoring subjects at time of AF (hazard ratio [HR]: 1.96; 95% confidence interval [CI]: 1.10 to 3.49) or when modeling AF as a time-varying exposure (HR: 2.00; 95% CI: 1.16 to 3.45). Among subjects with ESVEA who developed a stroke, 14.3% had diagnosed AF before their stroke. The incidence of stroke in subjects with ESVEA and a CHA2DS2-VASc (congestive heart failure, hypertension, age 75 years or older, diabetes mellitus, previous stroke or transient ischemic attack, vascular disease, age 65 to 74 years, female) score of ≥2 was 2.4% per year, comparable to the risk observed in AF. In day-to-day analysis, ESVEA was a consistent finding.

CONCLUSIONS: ESVEA was associated with an increased risk of ischemic stroke beyond manifest AF in this middle-aged and older population. Stroke was more often the first clinical presentation, rather than AF, in these study subjects.