Cryptogenic Stroke and Underlying Atrial Fibrillation

TLDR

Current guidelines recommend at least 24‑hour ECG monitoring after ischemic stroke, yet the optimal duration and type of monitoring remain undefined and 20–40% of strokes remain cryptogenic. The study aimed to determine whether long‑term monitoring with an insertable cardiac monitor (ICM) is more effective than conventional follow‑up for detecting atrial fibrillation after cryptogenic stroke. In a randomized trial of 441 patients aged ≥40 without prior AF, participants were randomized within 90 days of stroke to receive an ICM or standard care, with the primary endpoint being time to first AF episode >30 s within 6 months (secondary at 12 months). ICM detected atrial fibrillation in 8.9% of patients by 6 months and 12.4% by 12 months, versus 1.4% and 2.0% in the control group, yielding hazard ratios of 6.4 and 7.3 (P < 0.001), confirming superior detection with ICM. Funded by Medtronic; trial registered as CRYSTAL AF (ClinicalTrials.gov NCT00924638).

Abstract

Current guidelines recommend at least 24 hours of electrocardiographic (ECG) monitoring after an ischemic stroke to rule out atrial fibrillation. However, the most effective duration and type of monitoring have not been established, and the cause of ischemic stroke remains uncertain despite a complete diagnostic evaluation in 20 to 40% of cases (cryptogenic stroke). Detection of atrial fibrillation after cryptogenic stroke has therapeutic implications.We conducted a randomized, controlled study of 441 patients to assess whether long-term monitoring with an insertable cardiac monitor (ICM) is more effective than conventional follow-up (control) for detecting atrial fibrillation in patients with cryptogenic stroke. Patients 40 years of age or older with no evidence of atrial fibrillation during at least 24 hours of ECG monitoring underwent randomization within 90 days after the index event. The primary end point was the time to first detection of atrial fibrillation (lasting >30 seconds) within 6 months. Among the secondary end points was the time to first detection of atrial fibrillation within 12 months. Data were analyzed according to the intention-to-treat principle.By 6 months, atrial fibrillation had been detected in 8.9% of patients in the ICM group (19 patients) versus 1.4% of patients in the control group (3 patients) (hazard ratio, 6.4; 95% confidence interval [CI], 1.9 to 21.7; P<0.001). By 12 months, atrial fibrillation had been detected in 12.4% of patients in the ICM group (29 patients) versus 2.0% of patients in the control group (4 patients) (hazard ratio, 7.3; 95% CI, 2.6 to 20.8; P<0.001).ECG monitoring with an ICM was superior to conventional follow-up for detecting atrial fibrillation after cryptogenic stroke. (Funded by Medtronic; CRYSTAL AF ClinicalTrials.gov number, NCT00924638.).