Response by Parkash et al to Letters Regarding Article, “Effect of Aggressive Blood Pressure Control on the Recurrence of Atrial Fibrillation After Catheter Ablation: A Randomized, Open-Label Clinical Trial (SMAC-AF [Substrate Modification With Aggressive Blood Pressure Control])”
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We thank Jin-shan and Xue-bin, Kosiuk et al, and Ye et al for their interest in our study1 and for raising some important points.
The intent of the SMAC-AF study (Substrate Modification with Aggressive Blood Pressure Control) was to focus on both the initiating triggers and maintaining substrate for atrial fibrillation (AF) that result from hypertension, testing whether aggressive blood pressure control could modify the outcomes of catheter ablation. There are 3 potential mechanisms by which blood pressure treatment may affect the substrate involved in the maintenance of AF: (1) reduction in left ventricular diastolic pressure, leading to improved left ventricular hemodynamics, thereby decreasing atrial stretch; (2) reduction of fibrosis; and (3) effects on ion channel function.2 Chronically elevated blood pressure (BP) has been demonstrated in animal models to result in significant conduction abnormalities, shortening of atrial wavelength, and increased AF.2 Further studies demonstrated functional changes in the atrium as quickly as 15 weeks by using magnetic resonance …