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.” 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. 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. AF currently affects ≈5 million Americans and has a lifetime risk of 1:4 over age 40. Compared with those without AF, those with AF carry a 5-fold higher future stroke risk, and unanticoagulated AF doubles recurrent stroke risk. AF represents 15% to 20% of all ischemic strokes and half from cardiac etiology. Besides this substantial morbidity, the mortality of AF-related strokes is 24% by 1 month and 50% at 1 year. Thus, guidelines recommend at least 24 hours of ECG telemetry after stroke but encourage longer monitoring: the American Academy of Neurology in 2014 stated, “Clinicians might obtain rhythm studies for prolonged periods (eg, 1 or more weeks) instead of shorter periods (eg, 24 hours) in cryptogenic stroke without known AF, to increase yield of identification of occult AF” and the American Heart/Stroke Association in 2011 advocated, “For patients who have stroke with no apparent cause, prolonged rhythm monitoring (≈30 days) for AF is reasonable within 6 months of the event.” But do physicians adhere to this or instead follow House of God, doing nothing? Edwards et al admonishes hasty, nihilistic stroke-etiology decision-making. Quickly decreeing patients’ cryptogenic without further monitoring seems ubiquitous, especially given its prevalence of ≈30% of all strokes. Yet, compared with conventional methods, long-term monitoring after stroke significantly increases detection of AF, decreasing cryptogenics. In an analysis of 17 studies of long-term monitoring, the AF detection rate jumped as high as 23% in cryptogenics, with longer monitoring demonstrating greater yield. In 2016, armed with our cornucopia of high-tech, wi-fi, mobile cardiac telemetry systems (transdermal devices wearable for weeks, subcutaneously inserted loop recorders logging rhythms for years, and previously installed pacemakers and defibrillators, interrogated readily), any rush to conclude cryptogenic seems impetuous. Perhaps including long-term monitoring in standard evaluation instead of advanced evaluation of stroke could motivate lethargic physicians? Anchoring bias and premature closure involve fixating upon one diagnosis and avoiding auxiliary evidence. After an unrevealing standard evaluation in a third of stroke patients, that pesky cryptogenic moniker anchors in our mind, stuffing these patients into a diagnostic grab bag. Good luck, take an aspirin. We say this after a limited hospitalization stay, excluding only a few of the 200 known causes of stroke and despite the panoply of detection technologies available. Do not end the search at discharge! Is not the point of screening to uncover true positives, provide appropriate therapy and prevent disease recurrence? Clearly, fewer monitors are ordered than indicated. There are barriers. First, cumbersome logistics: many patients, discharged from tertiary stroke centers and transferred by helicopter from distant smaller hospitals, may lack transportation, physical ability, or means to follow up. Second, physicians may decline monitoring because of its weighty responsibility: fastidiously interpreting results, coordinating interdisciplinary opinions, initiating treatment, checking laboratories, and exposing to anticoagulating liabilities (namely intracerebral hemorrhage). Third, long-term monitoring requires ancillary staff to educate patients on device instruction. Fourth, patients may disuse the monitor (claiming “it fell off” or even “I don’t like/need/want it”), but this nonadherence is probably alike other tests, laboratories, and medications. What biomarkers augment AF yield with monitoring? Older age, strokes in multiple brain territories, especially the cortex, and echocardiography showing left atrial dilatation, strain, big appendage, and single-lobe morphology. Seek and Ye Shall Find Fibrillations