CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 2, March/April 2022 62 AFRICA The percentages of success and failure however did not differ significantly from a 50:50 ratio (p = 0.325; Z-test). Therefore, there were not significantly more patients in sinus rhythm than those with non-sinus rhythm at three months after cardioablation. Beyond three months, the results showed an increase in the percentage of patients in sinus rhythm, although the actual numbers of patients analysed declined substantially from 51 at zero to three months to 21 at a period above two years (Fig. 3). This was due to unrecorded rhythm status in some patients at each period, and loss to follow up as some patients were referred back to their district hospitals. The immediate post-operative success rate of the procedure during the first three months shows a greater success rate of 65.6% in the good ejection fraction than the poor ejection fraction group (42.1%). However, the result marginally failed to reach statistical significance with a p-value of 0.07 (Z-test). All patients who were in sinus rhythm at three months were further analysed to establish those with good versus poor ejection fraction. Of the 29 patients in sinus rhythm, 72.4% (n = 21) had an ejection fraction of 50% and above, while only 27.6% (n = 8) had a poor ejection fraction below 50% (p = 0.016; Z-test). Therefore, there were significantly more patients with a good ejection fraction who converted to sinus rhythm after cardiac ablation compared to those with a poor ejection fraction (Fig. 4). Regarding left atrial size, there was no difference from a 50:50 probability in outcome of ablation as there was a 59.1% (p = 0.395; Z-test) and a 55.2% (p = 0.575; Z-test) success rate for patients with left atrial sizes of 60 mm and above versus less than 60 mm, respectively. Patients with moderate to severe tricuspid regurgitation had a lower immediate success rate at zero to three months after surgery compared to those without or with mild regurgitation [54.8% (p = 0.596; Z-test) and 60.0% (p = 0.373; Z-test), respectively]. This was not statistically different from a 50:50 probability, even at the six- and 12-month periods. Although conclusions cannot be made without statistical significance, the diverging curves suggested possible wider differences with longer Table 2. Patients’ pre-operative left atrial sizes Left atrial size (mm) Frequency (n) Percentage 30–39 1 1.9 40–49 13 24.5 50–59 17 32.1 60–69 16 30.2 70–79 3 5.7 80–89 3 5.7 Total 53 100 Table 3. The frequency of pre-operative left-sided valve disease and specific valve lesions Mitral valve disease Aortic valve disease Frequency (n) – AR 1 MMVD – 21 MMVD AR 8 MMVD MAVD 7 MR – 7 MR AR 1 MS – 6 MS AR 1 MS AS 1 Total 53 MR: mitral regurgitation; MS: mitral stenosis; MMVD: mixed mitral valve disease; AR: aortic regurgitation; AS: aortic stenosis; MAVD: mixed aortic valve disease. Percentage 0 15 30 45 60 Rhythm at 0–3 months AF Flutter Sinus Percentage Frequency 39.2 20 3.9 2 29 56.9 Fig. 2. The overall immediate success rate. An initial 56.9% success rate was achieved with concomitant ablation. The percentage of the total number of patients is shown, whereas frequency is the absolute number of patients in each category. Duration post cardio-ablation (months) 56.9 64.9 63.3 75 71.4 0–3 3–6 6–12 12–24 Above 24 Percentage of patients in sinus rhythm Fig. 3. Proportions of patients in sinus rhythm over time, which increased over time and did not fall below the initial baseline success rate. Ejection fraction categories 0 20 Percentage of sinus rhythm 80 60 40 20 0 27.6 72.4 Fig. 4. Proportions of patients in sinus rhythm according to ejection fraction. More than 72% immediate success was achieved in patients with good ejection fractions (p = 0.016; Z-test).
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