Unmasking atrial repolarization to assess alternans, spatiotemporal heterogeneity, and susceptibility to atrial fibrillation

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• 作者：Richard L. Verrier ; PhD ; FHRS^* ; ^&dagger ; ; ^{rverrier@bidmc.harvard.edu" class="auth_mail" title="E-mail the corresponding author} ; Henrique Fuller ; BS^* ; ^&Dagger ; ; Fernanda Justo ; BS^* ; ^&Dagger ; ; Bruce D. Nearing ; PhD^* ; ^&dagger ; ; Sridharan Rajamani ; PhD^§ ; ; Luiz Belardinelli ; MD^§ ;
• 关键词：AF ; atrial fibrillation ; APB ; atrial premature beat ; APD ; action potential duration ; LCx ; left circumflex ; MAP ; monophasic action potential ; MMA ; modified moving average ; PTa ; atrial PT interval ; STa ; Atrial ST segment ; Ta ; atrial T (repolarization) wave ; TWAa ; atrial T-wave alternans ; TWHa ; atrial T-wave heterogeneity ; VNS ; vagus nerve stimulation
• 刊名：Heart Rhythm
• 出版年：2016
• 出版时间：April 2016
• 年：2016
• 卷：13
• 期：4
• 页码：953-961
• 全文大小：1507 K

文摘

Detection of atrial repolarization waves free of far-field signal contamination by ventricular activation would allow investigation of atrial electrophysiology and factors that influence susceptibility to atrial tachycardia and atrial fibrillation (AF).

Objective

50">The purpose of this study was to identify means for high-resolution intracardiac recording of atrial repolarization (T_a) waves using standard clinical electrocatheters and to assess fundamental electrophysiologic properties relevant to AF risk.

Methods

In alpha-chloralose anesthetized Yorkshire pigs, we studied effects of vagus nerve stimulation (VNS) on PT_a and QT intervals and effects of acute atrial ischemia or administration of intrapericardial acetylcholine followed by intravenous epinephrine on susceptibility to AF.

Results

Electrocatheters with closely spaced (1-mm) electrode pairs yielded high-resolution tracings of atrial repolarization waves. These recordings permitted detection of differential effects of right or left VNS, which shortened atrial PT_a interval by 30% vs 21% (P <.01) and lengthened QT interval by 1.5% vs 9%, respectively (P <.05). During atrial ischemia, ST_a segments were elevated 3.4-fold (P <.01), and the threshold for inducing AF was reduced 3.1-fold (P = .004). Ischemia amplified atrial T-wave alternans (TWA_a) and spatiotemporal heterogeneity (TWH_a) by 23- and 13-fold, respectively, in inverse correlation to AF threshold (r = 0.74, P <.01; r = 0.61, P = .03). TWA_a and TWH_a increased by 4.5- and 2-fold shortly before autonomically triggered atrial premature beats and AF.

Conclusion

This study used standard electrocatheters to demonstrate that TWA_a and TWH_a analysis provides means to assess vulnerability to AF without provocative electrical stimuli. These parameters could be evaluated in the clinical electrophysiology laboratory to determine risk for this prevalent arrhythmia and efficacy of contemporary and new agents.