CARDIOVASCULAR JOURNAL OF AFRICA • Volume 35, No 2, May – August 2024 112 AFRICA BP measurements prior to the RDN procedure were used as baseline BP values. Before treatment and at each follow-up office visit, investigators interviewed patients to document changes in antihypertensive medication. All patients in the GSR were treated with the Symplicity RDN system (Medtronic, Santa Rosa, CA) using a Symplicity FlexTM or Symplicity SpyralTM catheter. Statistical analysis Continuous data are reported as means (standard deviations) for normally distributed data. Categorial data are presented as percentages. Analyses were performed under the consideration of the intention-to-treat principle. All analyses were performed using the SAS statistical package (version 9.3 or higher). Results At the time of the analysis, 36 patients, with a mean age of 55.4 ± 9.9 years, had been enrolled in the GSR South Africa across nine centres. Seventeen of the patients were male, 10 were of African descent and four were current smokers. Baseline characteristics are presented in Table 1. At baseline, the mean office systolic and diastolic BP were 164.0 ± 20.4 and 95.0 ± 13.4 mmHg, respectively. The mean 24-hour ambulatory systolic and diastolic BP at baseline were 153.4 ± 14.5 and 87.6 ± 10.6 mmHg, respectively. Sixteen patients (45.7%) had type 2 diabetes mellitus, five (13.9%) had had a previous myocardial infarction, six (16.7%) had had a previous percutaneous coronary intervention, three (8.3%) had had a previous coronary artery bypass graft and two (5.7%) were reported to have had a previous stroke. Patients were prescribed a median of four anti-hypertensive medications at baseline, which persisted to 12 months [interquartile range (IQR) 4–5]. Calcium channel blockers were the most common prescribed antihypertensive medication (83.3%), followed by diuretics (66.7%), beta-blockers (66.7%), angiotensin receptor blockers (63.9%), alpha-adrenergic blockers (58.3%), ACE inhibitors (30.6%), aldosterone antagonists (25%), centrally acting sympatholytics (13.9%), and direct acting vasodilators (5.6%) (Table 2). The median number of prescribed medications remained constant to 12 months, despite overall reduction in office and 24-hour SBP. Overall, systolic BP was reduced at three to 12 months from baseline following RDN in the South African population (Fig. 1). The median change in office systolic BP was –14.3 mmHg (25th to 75th percentile: –31.5 to 0.5 mmHg) at three months; –17.0 mmHg (–11.7 to 0.0 mmHg) at six months; and –17.3 mmHg (–30.0 to –1.3 mmHg) at 12 months. Among patients of African descent, there was a median change of –17.7 mmHg (–25.3 to –8.0 mmHg) in office systolic BP at 12 months. In the South Africa GSR population, the median change in 24-hour ambulatory systolic BP was –13.0 mmHg (–27.0 to 4.0 mmHg) at three months; –9.5 Table 1. Baseline demographic characteristics and baseline BP readings (n = 36) Baseline characteristics Values Age (years), mean (± SD) 54.4 (9.9) Male, n (%) 17 (47.2) Current smoker, n (%) 4 (11.1) Diabetes mellitus (type 2), n (%) 16 (45.7) Sleep apnoea, n (%) 4 (12.1) Previous MI, n (%) 5 (13.9) Previous PCI, n (%) 6 (16.7) Previous CABG, n (%) 3 (8.3) Previous stroke, n (%) 2 (5.7) Baseline BP, mean (± SD) Office SBP (mmHg) 164.0 (20.4) Office DBP (mmHg) 95.0 (13.4) 24-hour SBP (mmHg) 153.4 (14.5) 24-hour DBP (mmHg) 87.6 (10.6) MI, myocardial infarction; PCI, percutaneous coronary intervention; CABG, coronary artery bypass graft; SBP, systolic blood pressure; DBP, diastolic blood pressure. Table 2. Antihypertensive medication usage at baseline (n = 36) Medication Values Median number of anti-hypertensive medication classes, n (IQR) 4.0 (4.0–5.0) Antihypertensive treatment, n (%) 36 (100.0) Medication, n (%) ACE inhibitors 11 (30.6) Angiotensin receptor blockers 23 (63.9) Calcium channel blockers 30 (83.3) Diuretics 24 (66.7) Aldosterone antagonists 9 (25.0) Spironalactone 7 (19.4) Centrally acting sympatholytics 5 (13.9) Direct renin inhibitors 0 (0.0) Beta-blockers 24 (66.7) Alpha-adrenergic blocker 21 (58.3) Direct-acting vasodilators 2 (5.6) IQR: interquartile range, between 25th and 75th percentiles. 0 –2 –4 –6 –8 –10 –12 –14 –16 –18 –20 Median change in office SBP (mmHg) Baseline n = 36 3 months n = 28 6 months n = 23 12 months n = 22 –14.3 (–31.5, 0.5) –17.0 (–11.7, 0.0) –17.3 (–30.0, –1.3) 0 –2 –4 –6 –8 –10 –12 –14 –16 Median change in 24-hour SBP (mmHg) Baseline n = 36 3 months n = 15 6 months n = 14 12 months n = 9 –13.0 (–27.0, 4.0) –9.5 (–17.0, –1.0) –15.0 (–29.0, –6.0) Fig. 1. Changes in (A) office and (B) 24-hour systolic BP from baseline to 12 months after RDN. A B
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