The sympathetic innervation of the heart in patients with hypertension and persistent atrial fibrillation before and after radiofrequency ablation
The aim of the study was to evaluate sympathetic innervation of the heart in patients with hypertension and persistent atrial fibrillation (AF) before and after radiofrequency catheter ablation (RFA). A total of 27 patients with stage I-II hypertension (degree 1 -3) were included in the study. Patients with persistent AF (n=17) received intracardiac procedure and RFA (isolation of pulmonary vein antrum, posterior wall of the left atrium, and left isthmus of the heart). Ten patients did not have AF. Efficacy of RFA was assessed after 12 months. All patients were divided into subgroups according to the presence of the arrhythmia recurrence. Radionuclide scintigraphy with <sup>123</sup>I-metaiodbenzylguanidine ( <sup>123</sup>I-MIBG) was performed to evaluate sympathetic activity of the myocardium. We estimated general sympathetic activity by the heart/ mediastinum (H/M) ratio and the indicator washout rate. Regional sympathetic activity was assessed by measuring the filling defect of <sup>123</sup>I-MIBG. The analysis of data showed that the H/M ratio was significantly lower in patients with AF compared with the corresponding value in patients without AF (1.70±0.14 vs. 1.96+0.08 on early scintigrams, р=0.005; 1.68+0.12 vs. 2.0±0.14 on delayed scintigrams, р=0.001). These results indicate that AF contributes to the worsening of the heart sympathetic activity in the presence of hypertension. Subjective improvement of the health and improvement in the general sympathetic cardiac function were observed in all patients after RFA: the early and delayed H/M ratios significantly increased from 1.70+0.14 to 1.97±0.21 (р=0.001) and from 1.68+0.12 to 1.96±0.12 (р=0.003), respectivley. The significant improvement in both general and regional sympathetic cardiac function was shown in patients with the efficient RFA compared with the subgroup of recurrent AF (early H/M ratio of 2.0+0.17 in patients with effective RFA vs. 1.77±0.01 in patients with ineffective RFA, p=0.021; indicator washout rate of 9.5±1.24% vs. 17.9±1.05%, p=0.004; <sup>123</sup>I-MIBG filling defect of 6.8+0.43% vs. 13.5±0.75%, p=0.001, correspondingly).