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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 1, January/February 2018
AFRICA
47
All the patients admitted to the medical wards with a confirmed
diagnosis of acute heart failure (AHF) from 1 January to 31
December 2014 were recruited. The patients were selected if they
met the Framingham clinical criteria
17
for the diagnosis of HF
and confirmed on echocardiography.
Demographic data were obtained from all patients aged 18
years andolderwhogavewritten, informed consent. The hospital’s
ethics committee approved the study. The NYHA functional
class, and baseline clinical and demographic characteristics of
patients were obtained using a structured questionnaire. All study
subjects underwent full clinical examinations, anthropometric
measurements and relevant investigations, including chest
radiography, electrocardiogram and echocardiogram.
Blood pressure was measured with a standard mercury
sphygmomanometer (cuff size 12.5
×
40 cm) using standard
protocols. Systolic and diastolic blood pressures were taken at
Korotkoff phases 1 and 5, respectively, to the nearest 2 mmHg.
18
Hypertension was deemed present if systolic blood pressure
was 140 mmHg or above and/or diastolic blood pressure was 90
mmHg or above on at least two occasions, or if the patient was
receiving anti-hypertensive drug treatment.
18
Waist circumference was measured in centimetres at the
midpoint between the lower costal margin and the iliac crest,
with the patient standing and the feet positioned close together.
The value was read at the end of a normal expiration.
19
Waist
circumference was considered increased if greater than 88 cm in
women and 102 cm in men.
19
Hip circumference was measured
similarly but at the level of the greater trochanter. Waist–hip ratio
was calculated using the formula: waist (cm)/hip (cm).
19
Weight
was measured with a mechanical weighing scale with the subject
wearing only light clothing, and height was measured using a
stadiometer with the subject standing with feet together, without
shoes or head gear. The reading was taken to the nearest 0.5 cm.
Body mass index (BMI) was calculated using the formula
weight (kg)/height
2
(m). BMI status was classified according to
the WHO criteria as normal weight (18.5–24.9 kg/m
2
), overweight
(25–29.9 kg/m
2
), class I obesity (30.0–34.9 kg/m
2
), class II obesity
(35.0–39.9 kg/m
2
), and morbid obesity (
≥
40 kg/m
2
).
19
Blood samples were collected from all patients and analysed
for haemoglobin level, fasting lipid profile, and serum urea,
creatinine and plasma glucose levels. Serum creatinine level was
used to calculate the eGFR with the Cockcroft–Gault formula.
20
Severity of renal impairment was classified using the National
Kidney Foundation-developed criteria as part of its Kidney
Disease Outcomes Quality Initiative (NKF KDOQI) to stratify
chronic kidney injury.
21
Fasting serum cholesterol and triglyceride levels were
measured using the enzymatic method with a reagent from
Atlas Medical Laboratories. Fasting high-density lipoprotein
(HDL) cholesterol was measured with the precipitation method.
Low-density lipoprotein (LDL) cholesterol values were calculated
using the Friedwald equation when the triglyceride level was less
than 4.0 mmol/l: LDL
=
TC – (HDL
+
TG /2.2).
22
Standard 12-lead elctrocardiography was performed for all
patients and the parameters assessed included presence of atrial
fibrillation, pathological Q waves, left ventricular hypertrophy,
QT prolongation and ST abnormalities. Transthoracic
echocardiography was performed on all the subjects and
assessments were done according to the recommendations of the
American Society of Echocardiography.
23
Left ventricular (LV) systolic performance was assessed using
fractional shortening (FS) and the ejection fraction (EF) of the
left ventricle. These were calculated automatically by the machine
using the Teichoiz formula.
24
Left ventricular mass (LVM) was
calculated using the American Society of Echocardiography
recommended formula for estimation of LV mass from LV linear
dimensions.
25
Left ventricular mass index (LVMI) was calculated
by indexing the LVM to the body surface area. Left ventricular
hypertrophy (LVH) was defined in absolute terms as LVMI
>
115
g/m
2
in men and
>
95 g/m
2
in women.
25
LV diastolic function was
evaluated by studying the filling dynamics of the left ventricle, the
isovolumetric relaxation time (IVRT), pulmonary venous flow
and tissue Doppler imaging-derived myocardial wall velocities.
26
All the study patients were followed up for six months or until
death if the patient died before six months of follow up. They
were assessed during follow up by telephone contacts if they did
not keep out-patient appointments. The primary endpoints were
death due to any cause and rehospitalisation. The duration of
follow up was defined as the interval from the date of the index
examination at which the echocardiogram was obtained to the
date of death or the date of last contact. During six months
of follow up, clinical and echocardiographic parameters were
obtained and compared with initial values.
Statistical analysis
Data were analysed using the Statistical Package for Social
Sciences (SPSS) version 20.0. Results are presented as mean
±
standard deviation for continuous variables, while categorical
variables are expressed as proportions or percentages. Tables are
used to illustrate results where appropriate. Continuous variables
were compared by the Student’s
t
-test, while proportions or
categorical parameters were compared with the chi-squared
test or two-tailed Fisher’s exact test, as appropriate. Logistic
regression analysis was done where appropriate. A
p
-value of less
than 0.05 was considered statistically significant.
Results
A total of 160 patients, 84 females and 76 males, were studied
over the study period. The age range was 20 to 87 years with a
mean age of 52.49
±
13.89 years. A total of 16 subjects (10%)
were lost to follow up, 66 subjects (41.3%) improved clinically
and continued their regular out-patient clinic attendance for six
months, 57 subjects (35.6%) were rehospitalised for worsening of
HF symptoms, while 21 subjects (13.1%) died.
The socio-demographic profile of the patients did not have any
significant effect on rehospitalisation and mortality. There was a
significant association between rehospitalisation and NYHA
class, type of HF (systolic or diastolic HF), BMI, haemoglobin
level, LVEF and eGFR (Table 1). However, when the effects of
confounding variables were removed using the logistic regression
model, the real determinants of rehospitalisation were NYHA
class, type of heart failure, haemoglobin level and eGFR
(Table 2). There was a significant association between mortality
and NYHA class, haemoglobin level and LVEF (Table 3).
However after logistic regression analysis, only NYHA class and
haemoglobin level at presentation were the real determinants of
mortality (Table 4).