CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 3, April 2012
148
AFRICA
criteria have previously been described.
22,23
Briefly, men and
women of African descent were enrolled if they were 18 to 70
years of age and free of clinically significant cardiovascular or
non-cardiovascular disorders. All patients gave informed, written
consent.
Patients diagnosed as being hypertensive after a two-week
placebo run-in period were randomised if in addition, their
daytime diastolic blood pressure was 90 to 114 mmHg on
ambulatory monitoring. Eligible patients were randomised to
receive therapy as previously described.
23
Patients were followed
up at monthly intervals and if at the first monthly follow-up visit
the target blood pressure was not reached, the daily dose of the
first-line drug was increased. At two months, patients who had
still not achieved target blood pressure values received additional
antihypertensive agents and at a further follow-up visit, daily
doses were either increased or additional therapy added.
23
All patients randomised in the Baragwanath trial underwent
echocardiography at baseline. Patients were followed up for
13 months. However, only patients in whom high-quality
echocardiograms could be obtained were eligible for inclusion
in the follow-up echocardiographic sub-study. Of the 233
patients included in the sub-study, data on 103 were available
at 13 months. No significant differences were found in the
baseline characteristics between the 103 patients included in the
sub-study and the non-participants, except for body mass index
(BMI), which was higher in the participants (31.1
±
6.0 kg/m
2
)
than in the non-participants (29.5
±
5.9 kg/m
2
,
p
=
0.04).
At baseline and at follow-up visits, nurse-derived clinic blood
pressure was assessed after the patient had rested in the sitting
position for 10 minutes. Measurements were obtained three
times, consecutively, according to guidelines. The same nurse
performed the clinic blood pressure readings in all patients. Pulse
pressure was calculated as differences between systolic and
diastolic blood pressure. Furthermore, oscillometric SpaceLabs
(model 90207) devices were programmed to obtain blood
pressure readings every 15 minutes from 06:00 to 22:00 and
every 30 minutes from 22:00 to 06:00. The intra-individual blood
pressure means were weighted by the time interval between
successive blood pressure readings.
23
Twenty-four-hour blood
pressure control was defined as mean values of
<
130/80 mmHg,
and clinic blood pressure control as values of
<
140/90 mmHg.
At randomisation, four months and 13 months,
two-dimensional targeted M-mode (short-axis view)
echocardiograms were obtained with a Hewlett-Packard Sonos
2500 system using a 2.5-MHz transducer and analysed according
to the American Society of Echocardiography Convention.
24
All
measurements were recorded on videotape and analysed by the
same experienced echocardiographer who was unaware of the
clinical data of the patients. Replicate measurements of LVM
index showed that in the present study population, the inter-
observer and intra-observer coefficients of variation were 12.4
and 11.4%, respectively.
Left ventricular mass (LVM) was determined as previously
described and indexed (LVMI) to height
2.7
. Left ventricular
end-diastolic mean wall thickness (MWT) was calculated from
(LV end-diastolic septal wall thickness
+
LV end-diastolic
posterior wall thickness)/2. Left ventricular end-diastolic relative
wall thickness (RWT) was calculated from (LV end-diastolic
septal wall thickness
+
LV end-diastolic posterior wall thickness)/
LV end-diastolic diameter. Left ventricular hypertrophy (LVH)
was defined as an LVMI
>
51 g/m
2.7
in both women and men.
25
Concentric LVH was defined as the presence of LVH and
a RWT
>
0.45. Eccentric LVH was defined as the presence of
LVH and a RWT
≤
0.45. Concentric remodelling was defined
as the presence of a RWT
>
0.45, but without LVH. Normal LV
geometry was considered as the absence of LVH and a RWT
≤
0.45. An abnormal LV geometry was considered as the
presence of concentric LVH, eccentric LVH and or concentric
LV remodelling.
Statistical analysis
Database management and statistical analyses were performed
with SAS software, version 9.13 (SAS Institute Inc, Cary,
NC, USA). Data are expressed as mean
±
SD. Differences in
continuous variables between the patients assigned to each of
the four LV geometric patterns were identified on an ANOVA,
followed by the test of Scheffe, or the Kruskal-Wallis test when
the distribution was abnormal.
To assess changes in continuous variables from zero to four and
13 months of treatment, a repeated-measurements ANOVA was
performed. To compare the prevalence rates of the four patterns
of LV geometry at zero and 13 months of therapy, a Chi-square
test followed by Bonferroni correction was performed. To
evaluate longitudinal changes in the prevalence rates of the four
LV geometric patterns, a Mantel-Haenszel strategy for repeated
measurements (according to the SAS program) or a McNemar
test was performed. To identify predictors of abnormal geometry,
a stepwise multiple logistic regression model was used, where
age, gender, BMI and blood pressure were included in the model.
A
p
<
0.05 was considered to be statistically significant.
Results
Table 1 shows the characteristics at baseline of patients grouped
according to the mass and geometry of the left ventricle. At
baseline, 51.5% of patients had concentric LVH, while 19% had
eccentric LVH and 12% concentric LV remodelling. Therefore,
only 17.5% of the patients at baseline had a normal left ventricle.
The age and gender distribution across the four groups was
similar. However, patients with concentric LVH had a higher
BMI and off-treatment 24-hour clinic systolic blood pressure
(BP) and pulse pressure (PP). Patients with eccentric LVH had
a higher BMI.
Table 2 shows mean BP values and the percentage BP control
at baseline and after four and 13 months of antihypertensive
treatment. Over the four-month treatment period, 46% of
patients achieved clinic BP values of
<
140/90 mmHg, and
by 13 months of therapy, 64% had clinic BP values that were
<
140/90 mmHg. Over the four-month treatment period, 46%
of patients achieved 24-hour BP values of
<
130/80 mmHg and
by 13 months of therapy 47% had 24-hour BP values that were
<
130/80 mmHg.
At four and 13 months of follow up, one (1%) and 12
(11%) patients, respectively were receiving three or more
antihypertensive drug classes. Forty-one per cent (42/103) of the
patients after 13 months of treatment were receiving two or more
antihypertensive drug classes.
Table 2 also shows LVM, LV wall thickness, LV internal
diameters, the prevalence of LVH and the prevalence of an
increased LV relative wall thickness at baseline and after four
