Seek and Ye Shall Find Fibrillations

See related article, p 1982 . Law No. 10 in the satirical book House of God states, “If you don’t take a temperature, you can’t find a fever.”1 In essence, do not go looking for problems. However, what if finding that fever led to ordering a limb ultrasound, discovering a deep vein thrombosis, prescribing anticoagulation, and averting life-threatening pulmonary emboli? Similar logic now applies for atrial fibrillation (AF). It has been known for decades that AF directly causes ischemic stroke as fibrin-rich clots form in the left atrium, flicking off into the brain. However, AF is often paroxysmal and, hence, uncaptured on 12-lead ECG or inpatient telemetry—so what if, just a few days or weeks after stroke, finding that AF led to prescribing anticoagulation and averting massive, debilitating strokes? In a longitudinal cohort study, Edwards et al compiled over a decade of data (2003–2013) from the Ontario Stroke Registry—patients in normal sinus rhythm, without known AF, after ischemic stroke or TIA.2 Outcomes included the proportion who received at least 24-hour Holter cardiac monitoring within 30 and 90 days. They found that after adjusting for potential confounders, the majority of the registry’s 17 398 subjects did not receive even a 24-hour monitor at either time point. Almost none (<1%) underwent prolonged monitoring (over 60 hours). They conclude that this woeful underuse of cardiac monitoring has likely caused a population-wide overdiagnosis of cryptogenic strokes and underdiagnosis of AF.2 AF currently affects ≈5 million Americans and has a lifetime risk of 1:4 over age 40.3 Compared with those without AF, those with AF carry a 5-fold higher future stroke risk,4 and unanticoagulated AF doubles recurrent stroke risk.5 AF represents 15% …