CARDIOVASCULAR JOURNAL OF AFRICA • Volume 34, No 3, July/August 2023 AFRICA 153 arrhythmogenic cardiomyopathy was the leading cause of SCD, responsible for 21.1% of patients, followed by post-surgery congenital heart disease (13.2%). At least 40% of SCD children and young adults have a negative autopsy or have a structurally normal heart. This is described as sudden arrhythmic death syndrome (SADS).23 A clinically relevant cardiac gene mutation is detected in 13 to 27% of patients in whom post mortem genetic testing is performed.23,24 For example, Lahraouchi and colleagues performed post mortem genetic testing on 302 SCD victims with negative autopsy studies, and pathogenic or likely pathogenic variants were detected in 13%, mostly for catecholaminergic polymorphic ventricular Table 2. Device characteristics, indications and outcomes Variable Overall patient population, n = 38 Secondary prevention, n = 22 Primary prevention, n = 16 p-value Arrhythmic indication for ICD, n (%) Ventricular tachycardia 13 (34.2) 13 (59.1) 0 < 0.0001 Ventricular fibrillation 7 (18.4) 7 (31.8) 0 0.014 CPR, no documented arrhythmia 2 (5.3) 2 (9.1) 0 0.329 Type of ICD implanted, n (%) Single-chamber ICD 24 (63.2) 20 (90.9) 4 (25) < 0.0001 Dual-chamber ICD 8 (21.1) 2 (9.1) 6 (37.5) 0.05 CRT-D 6 (15.8) 0 6 (37.5) 0.003 CRT-D upgrade from single-chamber ICD 1 (2.6) 0 1 (6.3) – Primary cardiac diagnoses, n (%) Idiopathic dilated cardiomyopathy 10 (26.3) 2 (9.1) 8 (50) 0.007 Peripartum cardiomyopathy 4 (10.5) 0 4 (25) 0.025 Hypertrophic cardiomyopathy 1 (2.6) 0 1 (6.3) 0.421 Arrhythmogenic right ventricular cardiomyopathy 10 (26.3) 8 (36.4) 2 (12.5) 0.09 Cardiac sarcoidosis 1 (2.6) 0 1 (6.3) 0.421 Long-QT syndrome 2 (5.3) 2 (9.1) 0 0.329 Surgically repaired CHD, n (%) * 5 (13.2) 5 (22.7) 0 0.05 Myocarditis 2 (5.3) 2 (9.1) 0 0.329 No primary diagnoses made 3 (7.9) 3 (13.6) 0 0.183 Appropriate ICD shock 16 (42.1) 12 (54.5) 4 (25) 0.06 Inappropriate ICD shock 7 (18.4) 6 (27.3) 1 (6.3) 0.10 *Four patients with repaired tetralogy of Fallot and one patient with a repaired ventricular septal defect. ICD, implantable cardioverter defibrillator; CRT-D, cardiac resynchronisation therapy plus a defibrillator; CPR, cardiopulmonary resuscitation; CHD, congenital heart defects. Primary prevention Secondary prevention Primary prevention- censored Secondary preventioncensored Months since ICD implantation Cumulative survival 0 20 40 60 80 100 120 140 1.0 0.8 0.6 0.4 0.2 0.0 Log rank p = 0.87 Fig. 4. Kaplan–Meier curves depicting the cumulative survival difference between the primary- and secondary-prevention groups.
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