One-third of stroke and transient ischemic attack (TIA) are cryptogenic, and paroxysmal atrial fibrillation (PAF) has been suggested as a possible cause for these cryptogenic strokes. Multiple studies have recently evaluated long-term cardiac rhythm monitoring with good yield for PAF. The duration of monitoring varies between studies as well as the qualifying event definition. Moreover, the clinical significance of very brief atrial fibrillation events is unclear in the literature. This paper provides an overview of current advances in the detection of paroxysmal atrial fibrillation, the clinical and genetic factors predictive of arrhythmia detection, and the therapeutic dilemma concerning this approach. 1. Introduction One-third of stroke and transient ischemic attack (TIA) are cryptogenic requiring additional investigation and intervention [1]. Occult paroxysmal atrial fibrillation (PAF) has been suggested as a possible cause for these cryptogenic strokes [2]. Atrial fibrillation has been long associated with high risk of stroke, but most of this knowledge is derived from patient data from chronic atrial fibrillation. It has been suggested that PAF is more prevalent than persistent atrial fibrillation in stroke and TIA patients [3]. Anticoagulation therapy initiated after detection of atrial fibrillation (AF) provides an additional 40% risk reduction of stroke as compared to antiplatelet therapy alone [4]. Therefore, it is important to diagnose AF after an ischemic stroke to provide maximal stroke prevention therapy. Current standard of care dictates an admission electrocardiogram (ECG) and at least 24？h of continuous telemetry monitoring [5]. However, brief asymptomatic paroxysmal atrial fibrillation events may remain undetected by traditional methods of screening. Recent technological advances have made it possible to perform long-term cardiac rhythm monitoring up to months or even years after a stroke. 2. Definition Paroxysmal atrial fibrillation is not clearly defined in the literature. There is controversy over the duration and morphology of the ECG data in defining an event qualifying for atrial fibrillation. Studies evaluating the incidence of PAF in stroke and TIA patient populations have used different definitions adding confusion about the true incidence. In our paper, we have highlighted the need for a rigorous definition of paroxysmal atrial fibrillation especially in the light of widely used advanced rhythm monitoring devices. 3. Epidemiology Atrial fibrillation prevalence is associated with age with 0.5% at 50–59 years of age increasing
References
[1]
P. L. Kolominsky-Rabas, M. Weber, O. Gefeller, B. Neundoerfer, and P. U. Heuschmann, “Epidemiology of ischemic stroke subtypes according to TOAST criteria: incidence, recurrence, and long-term survival in ischemic stroke subtypes: a population-based study,” Stroke, vol. 32, no. 12, pp. 2735–2740, 2001.
[2]
R. C. S. Seet, P. A. Friedman, and A. A. Rabinstein, “Prolonged rhythm monitoring for the detection of occult paroxysmal atrial fibrillation in ischemic stroke of unknown cause,” Circulation, vol. 124, no. 4, pp. 477–486, 2011.
[3]
T. Rizos, A. Wagner, E. Jenetzky et al., “Paroxysmal atrial fibrillation is more prevalent than persistent atrial fibrillation in acute stroke and transient ischemic attack patients,” Cerebrovascular Diseases, vol. 32, no. 3, pp. 276–282, 2011.
[4]
R. G. Hart, L. A. Pearce, and M. I. Aguilar, “Meta-analysis: antithrombotic therapy to prevent stroke in patients who have nonvalvular atrial fibrillation,” Annals of Internal Medicine, vol. 146, no. 12, pp. 857–867, 2007.
[5]
H. P. Adams Jr., G. del Zoppo, M. J. Alberts, et al., “Guidelines for the early management of adults with ischemic stroke: a guideline from the American Heart Association/American Stroke Association Stroke Council, Clinical Cardiology Council, Cardiovascular Radiology and Intervention Council, and the Atherosclerotic Peripheral Vascular Disease and Quality of Care Outcomes in Research Interdisciplinary Working Groups: the American Academy of Neurology affirms the value of this guideline as an educational tool for neurologists,” Circulation, vol. 115, no. 20, pp. e478–e534, 2007.
[6]
J. C. Barthélémy, S. Féasson-Gérard, P. Garnier et al., “Automatic cardiac event recorders reveal paroxysmal atrial fibrillation after unexplained strokes or transient ischemic attacks,” Annals of Noninvasive Electrocardiology, vol. 8, no. 3, pp. 194–199, 2003.
[7]
L. A. Sposato, F. R. Klein, A. Jáuregui et al., “Newly diagnosed atrial fibrillation after acute ischemic stroke and transient ischemic attack: importance of immediate and prolonged continuous cardiac monitoring,” Journal of Stroke and Cerebrovascular Diseases, vol. 21, no. 3, pp. 210–216, 2012.
[8]
R. Stahrenberg, M. Weber-Krüger, J. Seegers et al., “Enhanced detection of paroxysmal atrial fibrillation by early and prolonged continuous holter monitoring in patients with cerebral ischemia presenting in sinus rhythm,” Stroke, vol. 41, no. 12, pp. 2884–2888, 2010.
[9]
D. Jabaudon, J. Sztajzel, K. Sievert, T. Landis, and R. Sztajzel, “Usefulness of ambulatory 7-day ECG monitoring for the detection of atrial fibrillation and flutter after acute stroke and transient ischemic attack,” Stroke, vol. 35, no. 7, pp. 1647–1651, 2004.
[10]
A. H. Tayal, M. Tian, K. M. Kelly et al., “Atrial fibrillation detected by mobile cardiac outpatient telemetry in cryptogenic TIA or stroke,” Neurology, vol. 71, no. 21, pp. 1696–1701, 2008.
[11]
D. J. Miller, M. A. Khan, L. R. Schultz et al., “Outpatient cardiac telemetry detects a high rate of atrial fibrillation in cryptogenic stroke,” Journal of the Neurological Sciences, vol. 324, no. 1-2, pp. 57–61, 2013.
[12]
A. Bhatt, A. Majid, A. Razak, M. Kassab, S. Hussain, and A. Safdar, “Predictors of occult paroxysmal atrial fibrillation in cryptogenic strokes detected by long-term noninvasive cardiac monitoring,” Stroke Research and Treatment, vol. 2011, Article ID 172074, 5 pages, 2011.
[13]
L. Elijovich, S. A. Josephson, G. L. Fung, and W. S. Smith, “Intermittent atrial fibrillation may account for a large proportion of otherwise cryptogenic stroke: a study of 30-day cardiac event monitors,” Journal of Stroke and Cerebrovascular Diseases, vol. 18, no. 3, pp. 185–189, 2009.
[14]
N. Gaillard, S. Deltour, B. Vilotijevic et al., “Detection of paroxysmal atrial fibrillation with transtelephonic EKG in TIA or stroke patients,” Neurology, vol. 74, no. 21, pp. 1666–1670, 2010.
[15]
A. C. Flint, N. M. Banki, X. Ren, V. A. Rao, and A. S. Go, “Detection of paroxysmal atrial fibrillation by 30-day event monitoring in cryptogenic ischemic stroke: the Stroke and Monitoring for PAF in Real Time (SMART) Registry,” Stroke, vol. 43, no. 10, pp. 2788–2790, 2012.
[16]
P. D. Ziegler, T. V. Glotzer, E. G. Daoud et al., “Incidence of newly detected atrial arrhythmias via implantable devices in patients with a history of thromboembolic events,” Stroke, vol. 41, no. 2, pp. 256–260, 2010.
[17]
V. Fuster, L. E. Rydén, D. S. Cannom et al., “ACC/AHA/ESC 2006 guidelines for the management of patients with Atrial Fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation): developed in collaboration with the European Heart Rhythm Association and the Heart Rhythm Society,” Circulation, vol. 114, no. 7, pp. e257–e354, 2006.
[18]
W. M. Pollak, J. D. Simmons, A. Interian Jr. et al., “Clinical utility of intraatrial pacemaker stored electrograms to diagnose atrial fibrillation and flutter,” Pacing and Clinical Electrophysiology, vol. 24, no. 4 I, pp. 424–429, 2001.
[19]
C. Eitel, D. Husser, G. Hindricks et al., “Performance of an implantable automatic atrial fibrillation detection device: impact of software adjustments and relevance of manual episode analysis,” Europace, vol. 13, no. 4, pp. 480–485, 2011.
[20]
Z. Binici, T. Intzilakis, O. W. Nielsen, L. K？ber, and A. Sajadieh, “Excessive supraventricular ectopic activity and increased risk of atrial fibrillation and stroke,” Circulation, vol. 121, no. 17, pp. 1904–1911, 2010.
[21]
T. V. Glotzer, E. G. Daoud, D. G. Wyse et al., “The relationship between daily atrial tachyarrhythmia burden from implantable device diagnostics and stroke risk: the TRENDS study,” Circulation, vol. 2, no. 5, pp. 474–480, 2009.
[22]
J. S. Healey, S. J. Connolly, M. R. Gold et al., “Subclinical atrial fibrillation and the risk of stroke,” The New England Journal of Medicine, vol. 366, no. 2, pp. 120–129, 2012.
[23]
A. M. Sinha, H. C. Diener, C. A. Morillo et al., “Cryptogenic Stroke and underlying Atrial Fibrillation (CRYSTAL AF): design and rationale,” American Heart Journal, vol. 160, no. 1, pp. 36.e1–41.e1, 2010.
[24]
J. Ip, A. L. Waldo, G. Y. H. Lip et al., “Multicenter randomized study of anticoagulation guided by remote rhythm monitoring in patients with implantable cardioverter-defibrillator and CRT-D devices: rationale, design, and clinical characteristics of the initially enrolled cohort. The IMPACT study,” American Heart Journal, vol. 158, no. 3, pp. 364.e1–370.e1, 2009.
[25]
D. Schwartzman, D. P. Blagev, M. L. Brown, and R. Mehra, “Electrocardiographic events preceding onset of atrial fibrillation: insights gained using an implantable loop recorder,” Journal of Cardiovascular Electrophysiology, vol. 17, no. 3, pp. 243–246, 2006.
[26]
R. Stahrenberg, F. Edelmann, B. Haase et al., “Transthoracic echocardiography to rule out paroxysmal atrial fibrillation as a cause of stroke or transient ischemic attack,” Stroke, vol. 42, no. 12, pp. 3643–3645, 2011.
[27]
D. Wallmann, D. Tüller, K. Wustmann et al., “Frequent atrial premature beats predict paroxysmal atrial fibrillation in stroke patients: an opportunity for a new diagnostic strategy,” Stroke, vol. 38, no. 8, pp. 2292–2294, 2007.
[28]
S. Malik, W. J. Hicks, L. Schultz et al., “Development of a scoring system for atrial fibrillation in acute stroke and transient ischemic attack patients: the LADS scoring system,” Journal of the Neurological Sciences, vol. 301, no. 1-2, pp. 27–30, 2011.
[29]
L. Suissa, D. Bertora, S. Lachaud, and M. H. Mahagne, “Score for the targeting of atrial fibrillation (STAF): a new approach to the detection of atrial fibrillation in the secondary prevention of ischemic stroke,” Stroke, vol. 40, no. 8, pp. 2866–2868, 2009.
[30]
E. I. Charitos, U. Stierle, P. D. Ziegler et al., “A comprehensive evaluation of rhythm monitoring strategies for the detection of atrial fibrillation recurrence: insights from 647 continuously monitored patients and implications for monitoring after therapeutic interventions,” Circulation, vol. 126, no. 7, pp. 806–814, 2012.
[31]
G. Hindricks, E. Pokushalov, L. Urban et al., “Performance of a new leadless implantable cardiac monitor in detecting and quantifying atrial fibrillation results of the XPECT trial,” Circulation, vol. 3, no. 2, pp. 141–147, 2010.
[32]
K. G. Haeusler, L. Koch, J. Ueberreiter et al., “Safety and reliability of the insertable Reveal XT recorder in patients undergoing 3 Tesla brain magnetic resonance imaging,” Heart Rhythm, vol. 8, no. 3, pp. 373–376, 2011.
[33]
H. Kamel, B. B. Navi, L. Elijovich et al., “Pilot randomized trial of outpatient cardiac monitoring after cryptogenic stroke,” Stroke, vol. 44, no. 2, pp. 528–530, 2013.
[34]
D. D. McManus, J. Lee, O. Maitas et al., “A novel application for the detection of an irregular pulse using an iPhone 4S in patients with atrial fibrillation,” Heart Rhythm, vol. 10, no. 3, pp. 315–319, 2013.
[35]
P. T. Ellinor, K. L. Lunetta, C. M. Albert, et al., “Meta-analysis identifies six new susceptibility loci for atrial fibrillation,” Nature Genetics, vol. 44, no. 6, pp. 670–675, 2012.
[36]
J. G. Smith, C. Newton-Cheh, P. Almgren, O. Melander, and P. G. Platonov, “Genetic polymorphisms for estimating risk of atrial fibrillation in the general population: a prospective study,” Archives of Internal Medicine, vol. 172, no. 9, pp. 742–744, 2012.
