Heart rate variability and stroke or systemic embolism in patients with atrial fibrillation.

Background: Stroke remains one of the most serious complications in atrial fibrillation (AF) patients and has been linked to disturbances of the autonomic nervous system.
Objective: The purpose of this study was to test the hypothesis that impaired cardiac autonomic function might be associated with an enhanced stroke risk in AF patients.
Methods: A total of 1922 AF patients who were in either sinus rhythm (SR group; n = 1121) or AF (AF group; n = 801) on a 5-minute resting electrocardiographic (ECG) recording were enrolled in the study. Heart rate variability triangular index (HRVI), standard deviation of normal-to-normal intervals, root mean square root of successive differences of normal-to-normal intervals, mean heart rate, 5-minute total power, and power in the high-frequency, low-frequency, and very-low-frequency ranges were calculated. Cox regression models were constructed to examine the association of heart rate variability (HRV) parameters with the composite endpoint of stroke or systemic embolism.
Results: Mean age was 71 ± 8 years in the SR group and 75 ± 8 years in the AF group. Thirty-seven patients in the SR group (3.4%) and 60 patients in the AF group (8.0%) experienced a stroke or systemic embolism during follow-up of 5 years. In patients with SR, HRVI <15 was the strongest HRV parameter to be associated with stroke or systemic embolism (hazard ratio 3.04; 95% confidence interval 1.3-7.0; P = .009) after adjustment for multiple confounders. In the AF group, no HRV parameter was found to be associated with the composite endpoint.
Conclusion: HRVI measured during SR on a single 5-minute ECG recording is independently associated with stroke or systemic embolism in AF patients. HRV analysis in SR may help to improve risk stratification in AF patients.
Competing Interests: Disclosures Dr Beer reports grants from the Swiss National Foundation of Science, The Swiss Heart Foundation, and Bayer; and lecture fees from Sanofi Aventis and Amgen, to the institution outside the submitted work. Dr Blum has received research grants from the Swiss National Science Foundation and the Swiss Heart Foundation, all for work outside the submitted study. Dr Bonati has received an unrestricted research grant from AstraZeneca; consultancy or advisory board fees or speaker honoraria from Amgen, Bayer, Bristol-Myers Squibb, and Claret Medical; and travel grants from AstraZeneca and Bayer, outside the submitted work. Dr Conen received consultancy fees from Roche Diagnostics and Trimedics; and speaker fees from Servier and BMS/Pfizer, outside the submitted work. Dr Kühne received personal fees from Daiichi Sankyo and grants from the Swiss National Science Foundation, Swiss Heart Foundation, Foundation for CardioVascular Research Basel, Bayer, Pfizer, Boston Scientific, BMS, Biotronik, and Daiichi Sankyo, outside the submitted work. Dr Krisai has speaker fees from BMS/Pfizer, outside the submitted work. Dr Müller reports fellowship and training support from Biotronik, Boston Scientific, Medtronic, Abbott/St. Jude Medical, and Biosense Webster; speaker honoraria from Biosense Webster, Medtronic, Abbott/St. Jude Medical, AstraZeneca, Daiichi Sankyo, Biotronik, MicroPort, Novartis, Zoll, and Bristol Myers Squibb; consultant fees from Biosense Webster, Medtronic, Abbott/St. Jude Medical, and Biotronik, outside the submitted work. Dr Moschovitis has received advisory board and/or speaker fees from Astra Zeneca, Bayer, Boehringer Ingelheim, Daiichi Sankyo, Gebro Pharma, Novartis, and Vifor, outside the submitted work. Dr Osswald received research grants from the Swiss National Science Foundation and Swiss Heart Foundation, Foundation for CardioVascular Research Basel, and F. Hoffmann-La Roche Ltd.; and educational and speaker grants from F. Hoffmann-La Roche Ltd., Bayer, Novartis, Sanofi, AstraZeneca, Daiichi-Sankyo, and Pfizer, outside the submitted work. Dr Reichlin has recieved research grants from the Swiss National Science Foundation, the Swiss Heart Foundation, and the sitem insel support funds; speaker/consulting honoraria or travel support from Abbott/SJM, Astra Zeneca, Brahms, Bayer, Biosense-Webster, Biotronik, Boston-Scientific, Daiichi Sankyo, Farapulse, Medtronic, Pfizer-,BMS and Roche; and support for his institution’s fellowship program from Abbott/SJM, Biosense Webster, Biotronik, Boston Scientific, and Medtronic for work, outside the submitted study. Dr Zuern has received funding from the “Freiwillige Akademische Gesellschaft Basel”; and personal fees from Cardiomatics, outside the submitted work. All other authors have no conflicts of interest to disclose.
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