Archives of the Turkish Society of Cardiology
P Wave Duration and P Wave Dispersion in Hyperthyroidism: Effect of Antithyroid Treatment [Turk Kardiyol Dern Ars]
Turk Kardiyol Dern Ars. 2004; 32(8): 556-563

P Wave Duration and P Wave Dispersion in Hyperthyroidism: Effect of Antithyroid Treatment

Yeşim GÜRAY1, Ümit GÜRAY1, M.Birhan YILMAZ1, Hakan ALTAY1, Halil KISACIK1, Serdar GÜLER2, Şule KORKMAZ1
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Atrial fibrillation is frequently encountered in patients with hyperthyroidism. Previously, it was shown that prolonged maximum P wave duration and increased P wave dispersion on 12-lead surface electrocardiograms (ECG) are closely related to the development of paroxysmal atrial fibrillation (PAF). In this study, these P wave parameters were measured from 12-lead surface ECG in hyperthyroid patients with or without PAF during sinus rhythm and compared to euthyroid controls. In addition, influence of pharmacologic antithyroid therapy on these P wave parameters was investigated. Fifty-two hyperthyroid patients were included in the study. All patients underwent 24-hour Holter recordings and then, patients were divided into two groups according to the presence (PAF+; n=29) or absence (PAF-; n=23) of PAF. Maximum P wave duration (P max), minimum P wave duration (P min) were measured from the 12-lead surface ECG and P dispersion (PWD=P max-P min) values were then calculated. P max values were found to be significantly longer in both PAF+ (114.8±11.6 ms) and PAF- (105.6±11ms) patient groups as compared to controls (91±7.6 ms; p<0.001 for both comparisons). PWD values of both PAF+ and PAF- groups were also significantly higher than the controls (53.3±12 ms, 43.6±10 ms and 31.2±5 ms, respectively; p<0.001 for both comparisons). Age-adjusted PWD were significatly associated with the prevalans of PAF. Moreover P max and PWD values were significantly higher in PAF+ group as compared to PAF- group (p=0.006 for P max, p=0.003 for PWD). There were no significant differences in P min among groups. After restoration of euthyroidism by antithyroid therapy, P max (106±10ms, p<0.001) and PWD (42.2±6.4 ms, p<0.001) were found to be significantly decreased in PAF+ group as compared to baseline. In PAF- patients, P max (97.7±14 ms, p=0.001) and PWD (34.5±6.4 ms, p<0.001) were also decreased. In both groups, no significant changes were detected in P min values between baseline and after treatment. It is concluded that prolongation of P max and PWD in hyperthyroid patients could reflect a propensity to develop atrial fibrillation. However, significant decline in both of these P wave parameters after management of hyperthyroidism is thought to be the result of decreased unfavorable effects of circulating thyroid hormones on atrial electrophysiology. (Türk Kardiyol Dern Arş 2004; 32: 556-563)

Keywords: Antithyroid therapy, hyperthyroidism, paroxysmal atrial fibrillation, P wave dispersion, P wave duration

How to cite this article
Yeşim GÜRAY, Ümit GÜRAY, M.Birhan YILMAZ, Hakan ALTAY, Halil KISACIK, Serdar GÜLER, Şule KORKMAZ. P Wave Duration and P Wave Dispersion in Hyperthyroidism: Effect of Antithyroid Treatment. Turk Kardiyol Dern Ars. 2004; 32(8): 556-563
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