CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 2, March/April 2022 AFRICA 61 radiofrequency ablation was used, and they had been offered surgery between 1 March 2013 and 30 April 2017. Exclusion criteria included patients with isolated ablation without valve surgery, the ablation and surgery were offered during separate operative settings (staged procedure), if the procedure was done outside the study period, and bi-atrial cardiac ablation or an alternative energy source was used other than unipolar radiofrequency. The standard procedure was saline-irrigated unipolar radiofrequency left atrial ablation during cardiopulmonary bypass with an arrested heart. During the procedure, ablation was done after valve excision (for replacement) and before valve replacement(s) or repair(s). A Medtronic® ablation pen was used to make a pulmonary vein isolation line, which was joined to the P2 mitral annulus (isthmus line). A running 4/0 Prolene® suture was used to close the left auricle ostium from the endocardial side. A 12-lead ECG was used by the cardiologist to record the patients’ rhythm. Possible post-operative rhythm outcomes included normal (sinus), atrial fibrillation, atrial flutter or other. These were categorically recorded every three months, between zero and three months, three and six months, six and nine months, nine and 12 months and then annually thereafter, at 12 to 24 months and more than 24 months. At least one cardiologist interpreted and recorded the patients’ rhythm at least once during these intervals during routine follow up. A successful outcome was sinus rhythm during the zero- to three-month period, while initial failure was any other outcome in the same period. Late success was a patient who had an initial failure but subsequently converted to sinus rhythm in the subsequent follow-up period. Relapse was a patient with an initial success in the first three months and then any other rhythm in the subsequent follow-up period. Statistical analysis Statistical analysis was performed on SAS (SAS Institute Inc, Carey, NC, USA), release 9.4 or higher, running under Microsoft Windows, by the statistician Prof HS Schoeman of Clinistat (Pty) Ltd. The percentage of sinus rhythm at each of the time points was tested for significance by comparing it to a chance outcome, using the Z-test for the normal approximation of the binomial distribution. Statistical significance testing was two-sided and a p-value < 0.05 was considered significant. Results A total of 53 patients was analysed, with 67.9% (n = 36) being female and 32.1% (n = 17) male. The mean age was 43.6 years, median was 48.0 years and standard deviation was 13.8 years. The interquartile range (IQR) was 34 to 53 years, minimum age was 16 years and maximum age was 70 years (Fig. 1). Moreover, 83.0% of patients (n = 44) were below the age of 60 years, with 35.9% (n = 19) of the whole study population falling in the 50- to 59-year age range. The majority (81.1%) of patients had no pre-operative co-morbidities (Table 1); 62.3% (n = 33) of patients had an ejection fraction (EF) of 50% and above, while 37.7% (n = 20) had a poor ejection fraction of less than 50% (median EF 55%; mean EF 53%, SD ± 9.0). About 62% (n = 33) of patients had left atrial (LA) sizes between 50 and 70 mm, with 17 patients in the 50- to 59-mm range and 16 measured 60 to 69 mm. The mean LA size was 57.3 mm (SD ± 11.2) with a median of 56 mm, while three patients were in the largest LA size range of 80 to 89 mm. The largest LA size was 87 mm, as measured by echocardiography (Table 2). Rheumatic mixed mitral valve disease (MMVD) made up a total of 67.9% (n = 36) of patients, either alone (n = 21) or in combination with aortic valve disease (n = 15), as shown in Table 3. Combinations of MMVD with aortic regurgitation (AR) and MMVD with mixed aortic valve disease (MAVD) were second and third most common after MMVD alone, with eight and seven patients in each category, respectively. With regard to right-sided valve disease, 34.0% of patients (n = 18) had severe tricuspid regurgitation, while 30.2% (n = 16) and 28.3% (n = 15) had mild and moderate tricuspid regurgitation, respectively. Four patients (7.8%) had no tricuspid regurgitation, and no tricuspid stenosis was noted. The immediate success rate of left atrial radiofrequency cardio-ablation in this study was 56.9% (n = 29) at zero to three months on 51 analysed patients, as the rhythm status was not recorded on two other patients. The procedure had a 43.1% (n = 22) failure rate between zero and three months, 39.2% (n = 20) of patients having atrial fibrillation, while 3.9% (n = 2) had atrial flutter rhythm (Fig. 2). Median (± SD) = 43.6 (± 13.82); Median (IQR) = 48 (34–53); min/max = 16/70 0 15 30 45 60 Age in years 0–19 20–29 30–39 40–49 50–59 60–69 70–79 Percentage Frequency 7.6 15.1 13.2 18.9 35.9 7.6 1.91 4 4 8 7 10 19 Fig. 1. The overall age distribution for all 53 patients (males and females combined). More than one-third of patients were between 50 and 59 years of age. Frequency is the absolute number of patients in each age range. Table 1. Patient pre-operative co-morbidities Co-morbidities Frequency (n) Percentage Cumulative % Diabetes 1 1.9 1.9 Epilepsy 1 1.9 3.8 HIV 2 3.8 94.3 Hypertension 2 3.8 7.6 Hypertension and diabetes 1 1.9 9.4 None* 43 81.1 90.6 Re-do surgery 2 3.8 98.1 Stroke 1 1.9 100 Total 53 100 HIV: human immunodeficiency virus. *More than 80% of patients had no co-morbidities.
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