A retrospective registry of patients presenting with cardiac tachyarrhythmia at a tertiary academic hospital in South Africa

Abstract

Background: Cardiac electrophysiology (EP) is a rapidly growing field in the health care sector globally. Evidence from European and American retrospective registries have shown that cardiac arrhythmias can be treated both medically and through intervention via catheter ablation. These registries have described disease burden, procedural success rates, and complication rates as well as patients' electrophysiological and clinical characteristics. Currently, there is minimal data describing these factors in South Africa (SA). Aims and objectives: The primary aim of this study was to describe the clinical characteristics, disease prevalence and the success and complication rates of EP procedures in the first year of a newly established service at a tertiary referral centre in SA. Methodology: Patients who were referred to the Tygerberg Hospital EP service in the year 2019 were retrospectively included. Clinical, electrophysiological, and echocardiographic data were anonymized, de-identified, and recorded into a password-protected Microsoft Excel case report form (CRF). For the continuous variables, means and standard deviations were used to analyse the data. For the categorical variables, the Pearsons chi-square tests and the Fisher exact tests were used. A p-value of <0.05 was regarded as statistically significant. Results: A total of 73 patients were retrospectively included in the study. Thirty-nine were males (53.0%) and 34 were females (47.0%). The mean age for this population was 49.5±14.3 years (males-mean 51.9±14.4 years; females-mean 46.8±13.7 years). Patients were symptomatic in the form of palpitations (n=55 [75.0%]), dyspnoea and pre-syncope (n=36 [49.3%] each). Beta-blockers were the most commonly used medication to treat patients in this study, being prescribed to 64 (87.6%) patients. There were 13 (17.8%) patients treated with medical therapy alone, and 60 (82.2%) patients were advised to undergo an EP study (EPS) with catheter ablation if indicated. Three patients declined this treatment, and 57 EPS were performed. Of the 57 patients undergoing an EPS, eight (14.0%) had diagnostic studies only, with four (7.0%) patients being non-inducible and four (7.0%) patients with arrhythmia substrate that were not ablated. The other 49 patients (86.0%) underwent catheter ablation. Twenty-one patients (39.6%) were diagnosed with atrial flutter (AFL), of which 19 (35.8%) underwent cavotricuspid isthmus (CTI) ablation. Twenty-nine (54.7%) patients were diagnosed with a paroxysmal supraventricular tachycardia (SVT). Of these 13 (24.5%) had atrioventricular nodal re-entry tachycardia (AVNRT), 15 (28.3%) had atrioventricular re-entry tachycardia (AVRT) and one patient had both AVNRT and AVRT. Atrial tachycardia (AT) was diagnosed in two patients (3.8%). In the 29 (54.7%) patients with SVT, 27 ablations were done in 26 patients, with 24 (92.3%) of the 26 patients having a successful procedure on the first attempt. Atrioventricular nodal ablations (AVNA) were performed on two patients with poorly controlled atrial fibrillation (AF). Only one (1.9%) patient underwent an EPS for ventricular tachycardia (VT) and this patient had a successful ablation for idiopathic right ventricular outflow tract (RVOT) VT. The success rate for ablation procedures in this cohort was 95.9%. Echocardiograms were available for 57 (78.1%) of the study population. As was to be expected, structural heart disease was more common in the AFL group compared to the SVT group, with this group having larger atria, larger ventricles, poorer LV function and more diastolic dysfunction than the SVT group (p<0.05 for all of these variables). At follow-up, patients reported a significant (78.6%) decrease in the prevalence of arrhythmia-related symptoms. Dyspnoea, palpitations, pre-syncope, and syncope were all significantly reduced, with a p-value <0.01. The need for cardioversion was also significantly reduced at follow-up with a p-value <0.01. Conclusion: This registry, the first of its nature in SA sought to identify disease prevalence, clinical characteristics of EP patients and the success and complication rates of ablation procedures. This provides novel setting-specific information. This study showed that referral for tertiary arrhythmia management was infrequent, with 73 patients referred in 2019. The most common arrhythmia was SVT, followed by AFL. Ablation procedures were safe and effective. Reasons for the low referral are likely to be multifactorial including lack of awareness on the part of patients and physicians, as well as logistical aspects