Effects of long-term beta-blocker therapy on P-wave duration and dispersion in patients with rheumatic mitral stenosis Ali Riza Erbay a , Hasan Turhan b, * , Ayse Saatci Yasar a , Asuman Bicer a , Kubilay Senen a , Hatice Sasmaz a , Irfan Sabah a , Ertan Yetkin b a Department of Cardiology, Turkiye Yuksek Ihtisas Hospital, Ankara, Turkey b Department of Cardiology, Inonu University Medical Faculty, Malatya, Turkey Received 25 November 2003; received in revised form 22 February 2004; accepted 5 March 2004 Available online 22 July 2004 Abstract Background: P-wave dispersion (PWD), has been defined as the difference between maximum and minimum P-wave duration. Prolonged P- wave duration and increased PWD have been reported to be related with increased risk for atrial fibrillation (AF). AF is the most common sustained arrhythmia encountered in patients with rheumatic mitral stenosis (MS). Beta-blockers are the mainstay of therapy in patients with rheumatic MS to control ventricular rate both during sinus rhythm and AF. In the present study, we aimed to evaluate the effect of long-term beta-blocker therapy on P-wave duration and PWD in patients with rheumatic MS. Method: Study population includes 46 patients (group I, 8 men, 38 women, mean age=34F8 years) with newly diagnosed moderate-to-severe rheumatic MS who have not taken any medication before and prescribed oral beta-blocker therapy and 46 healthy control subjects without any cardiovascular disease (group II, 8 men, 38 women, mean age=35F7 years). Mitral valve area, maximum and mean diastolic mitral gradients, left atrial diameter, and systolic pulmonary artery pressure were evaluated by transthoracic echocardiography before initiation of beta blocker therapy and repeated at the end of the first month. Baseline maximum and minimum P-wave duration and PWD were determined on 12-lead electrocardiogram recorded for each patient and control subject and repeated at the end of the first month after initiation of beta-blocker therapy in patient group. Results: Maximum P-wave duration and PWD were found to be significantly higher in patients with MS than those in control subjects (Maximum P-wave duration: 128F7 ms vs. 104F4 ms and PWD: 52F6 ms vs. 27F3 ms, p b0.001 for both). Both groups had comparable minimum P-wave duration (75F4 ms vs. 76F4 ms, p =0.093). Maximum P-wave duration and PWD were found to be significantly decreased by long-term beta blocker therapy (Maximum P-wave duration; 128F7 ms vs. 122F6 ms, p b0.001, PWD; 52F6 ms vs. 47F5 ms, pb0.001). However, there was no significant difference between the values of minimum P wave duration measured before and at the end of the first month of beta-blocker therapy (75F4 ms vs. 75F3 ms, p =0.678). Statistically significant decrease were detected on maximum and mean mitral gradient and systolic pulmonary artery pressure and resting heart rate at the end of the first month of beta-blocker therapy. However, only the change in resting heart rate was found to be significantly correlated with the decrease in maximum P-wave duration and PWD (Maximum P-wave duration: r =0.327, p =0.026, PWD: r =0.378, p =0.01). Conclusion: We have shown for the first time that long-term beta-blocker therapy causes a significant decrease in maximum P-wave duration and PWD in patients with rheumatic MS. D 2004 Elsevier Ireland Ltd. All rights resrved. Keywords: Mitral stenosis; P-wave dispersion; Beta-blocker; Atrial fibrillation 1. Introduction P-wave dispersion (PWD) has been defined as the difference between maximum and minimum P-wave dura- tion [1]. It is related with inhomogeneous and discontinuous 0167-5273/$ - see front matter D 2004 Elsevier Ireland Ltd. All rights resrved. doi:10.1016/j.ijcard.2004.03.079 * Corresponding author. Turkocagi caddesi 20. sokak, No: 2/2 Balgat 06520, Ankara Turkey. Tel.: +90 312 2867658. E-mail address: drhturhan@yahoo.com (H. Turhan). International Journal of Cardiology 102 (2005) 33 – 37 www.elsevier.com/locate/ijcard