43 / 62
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 1, January/February 2020
AFRICA
41
Systemic hypertension causes well-recognised structural and
functional changes in the heart, which are known as cardiac
remodelling. The spectrum of hypertensive heart disease is
characterised by left ventricular hypertrophy (LVH), atrial
remodelling and heterogeneity of atrial conduction, and fibrosis,
all of which can result in atrial fibrillation.
5
Although the effect
of hypertension on the left ventricle has been extensively studied,
its effect on the left atrium is less well defined.
6
Left atrial (LA) size has rapidly gained interest over
the years as some studies have shown its role in predicting
cardiovascular events.
7
Evidence suggests that LA remodelling
(LAR) occurs even before the development and detection
of LVH and is therefore an early sign of hypertensive heart
disease.
8
LA remodelling, characterised by LA enlargement,
has been associated with an increased risk of developing atrial
fibrillation and stroke.
9
Variables known to affect LA size are
age, obesity, race, body surface area and left ventricular mass.
10,11
The burden of chronically elevated blood pressure on LA size, as
demonstrated by an increasing size, has been shown in studies on
Caucasians and Asians.
12,13
Few studies have been conducted in
black hypertensive patients in sub-Saharan Africa.
The paucity of studies on LAR in black hypertensive patients
in the early phase of hypertension is a real concern. The
objectives of our study were three-fold: first, to determine the
difference in LA size between hypertensive and non-hypertensive
individuals, second, to determine the proportion of hypertensive
patients with LA enlargement, and third, to determine the
predictors of LA size in hypertensive patients.
Methods
This study was a cross-sectional, comparative study conducted
at the out-patient cardiology units of two hospitals in Douala,
Cameroon, namely the Douala General Hospital (DGH) and
Deido District Hospital (DDH), over a period of three months
from January to March 2017. These hospitals are among the
busiest hospitals in Douala, the economic capital of Cameroon,
which has a population of about three million people. Each
of these hospitals has a cardiology unit with an equipped
examination room and expert cardiologists.
Hypertensive patients (cases) were enrolled consecutively while
a non-hypertensive group (controls) was enrolled conveniently
and consisted of volunteers from hospital staff and patient
carers attending the DGH and DDH (all native Africans). Cases
were matched by age and gender to non-hypertensive control
subjects.
Hypertensive patients were native African adults who fulfilled
the following inclusion criteria: aged 18 years and above,
diagnosed with hypertension for less than a year to the period
of recruitment (drug naïve or treated), and with mild to
moderate hypertension. Patients with evidence (medical records)
of coronary heart disease, heart failure, valvular heart disease,
diabetes mellitus, co-existing cardiomyopathy or arrhythmia
were excluded. Controls were non-hypertensive patients with no
cardiovascular or renal diseases.
Ethical approval was obtained from the institutional review
board of the Faculty of Health Sciences of the University of
Buea. Written informed consent was obtained from all study
participants before their enrolment into the study. The study was
carried out in conformity to the Declaration of Helsinki.
Basic and clinical variables of all the subjects were collected.
These included age, gender, height and weight. Blood pressure
was measured with an appropriate-sized cuff on the right arm of
the patient after the subject had been seated quietly for at least
five minutes. Hypertension was diagnosed in subjects having
a systolic blood pressure (SBP) of more than 140 mmHg and
diastolic blood pressure (DBP) of more than 90 mmHg on at
least two separate occasions, or on anti-hypertensive therapy.
Files were reviewed to obtain recent laboratory results (less than
three months).
The procedure for urine collection was explained to each
participant and 5 ml of midstream urine of the first morning
void was used for each patient. Patients were asked to avoid
exercise or exertion at least 24 hours prior to urine collection.
The urine samples were analysed for microalbuminuria using a
microalbumin strip (microalbuPHAN
®
).
Two-dimensional Doppler and M-mode echocardiography
was performed using a commercially available machine (Vivid3
®
Sonoscape, as seen in Fig. 1) with a 3.5-MHz probe. Cardiac
echography was done by two experienced cardiologists with
subjects lying in the left lateral decubitus position. A one-lead
electrode was placed continuously during the course of the
examination. All cardiologists were given a protocol with
standard operating procedures for each measurement, which
was done according to previously published guidelines.
14
Measurements from at least three different cardiac cycles were
averaged and used in the analyses.
The LA anteroposterior linear dimension was obtained from
the parasternal long-axis view, from the trailing edge of the
posterior aortic wall to the leading edge of the posterior LA
Fig. 1.
A Vivid3
®
Sonoscape was used for two-dimensional
Doppler and M-mode echocardiography.