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VOLUME 13 NUMBER 1 • JULY 2016
RESEARCH ARTICLE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
was 3.9% (95% CI: 1.7–8.5%) and 4.5% (95% CI: 2.1–9.3%) for
men and women, respectively. At 180 days, the mortality rate was
7.3% (95% CI: 4.7–11.2%). This was 7.1% (95% CI: 3.8–12.7%)
and 7.5% (95% CI: 3.9–14.0%) for men and women respectively.
Patients with pericardial diseases had the highest early mortality
rate. Hypertensive HF subjects had the best survival rates (Figs 1, 2,
3). At 180 days, 13.9% of the subjects were rehospitalised at least
once (14.6% for women and 13.3% for men).
Table 4 shows the univariate correlates of survival in the cohort.
Mortality was associated with female gender, being single, HF
with normal ejection fraction, lower blood pressure, higher heart
and respiratory rates, higher body temperature, anaemia, high
creatinine levels and higher total white blood cell counts. Other
factors included higher QRS duration and corrected QT interval,
larger left atrial diameter and area, higher NYHA class and presence
of tricuspid and mitral regurgitation. In a multiple regression analysis
for predictors of mortality at 180 days, none of these variables
reached statistical significance.
Discussion
This is the first detailed study of the clinical profile and short- or
medium-term outcome of AHF cases in southern Nigeria. Similar
to our earlier observation,
24
AHF in our community predominantly
affects younger and middle-aged individuals who are in the prime
of their lives. Hypertensive heart disease and other non-ischaemic
aetiology contribute to over 90% of the cases.
The majority of our subjects presented with de novo acute HF.
Our findings with the use of some disease-modifying agents such
as angiotensin converting enzyme (ACE) inhibitors or angiotensin
II receptor blockers (ARBs), aldosterone antagonists (except for
beta-blockers and hydralazine–isosorbide combination) are
remarkably similar to findings in many other parts of the world.
6,8
Mortality rates in the short and medium term are relatively low,
and higher in women than men.
Our findings of relatively young age at presentation for AHF is
similar to reports from many parts of Africa.
1,4,25
AHF patients on
the continent are about 20 years younger than similar patients
in high-income countries.
6-9
This implies that HF afflicts our
population in their productive years, with attendant economic
loss to the society and greater disability-adjusted life years.
The comparable or even lower short- or medium-term mortality
rate of HF in our cohort compared to findings in high-income
countries is an important observation from this study.
7,8
Mortality
rates in our study were 4.2% (95% CI: 2.4–7.3%) and 7.3%
(95% CI: 14.7–11.2%) at 30 days and 180 days, respectively.
Unlike findings in high-income countries,
26,27
we noted that
age was not associated with poorer outcome in our cohorts. Our
finding of a better prognosis in obese individuals is similar to that
of other researchers.
27,28
In the Framingham study, high BMI was
associated with a better prognosis (HR for mortality per one SD:
0.88, 95% CI: 0.75–1.04 for men, and 0.86, 95% CI: 0.72–1.03
for women). This may also be consistent with the ‘obesity paradox’
in HF.
29-31
Underweight in HF patients may be indicative of cardiac
cachexia, and progression of HF and poor prognosis.
Lower blood pressure or pulse pressure was associated with
a poorer outcome. This may reflect advanced HF and decreased
stroke volume. This has been noted in previous studies.
26,32
It is now well known that impaired renal function is an
important predictor of all-cause mortality in HF.
33-35
This is similar to
the observation in our study. Patients with renal impairment often
develop cardio-renal syndrome, which is caused by low cardiac
output. These patients often develop multiple alterations at the
vascular level, leading to endothelial dysfunction, coagulation
abnormalities, insulin resistance, hyperhomocystinaemia and
activation of the sympathetic nervous system, as well as the renin–
angiotensin and aldosterone system. They are prone to unstable
HF and susceptible to high catecholamine levels. Furthermore
HF patients with renal dysfunction are also less likely to receive
proven medications for HF.
Hyponatraemia and hypokalaemia were associated with a better
prognosis in our study. This is contrary to most reports from the
Western world, although in a Polish study, Biegus
et al
.
8
reported
that hypokalaemia was associated with a better outcome. This
may be related to better response to diuretics in the survivors,
leading to the electrolyte derangement. It may also be speculated
that sodium may play a lesser role in the pathophysiology of HF
in our setting.
We also observed that left atrial size, left atrial area, left
ventricular size, higher E/A ratio and presence of mitral and
tricuspid regurgitation were associated with poorer outcomes.
This has been well recognised by earlier studies.
7,9
Left atrial
or ventricular size reflects left atrial or ventricular pressure and
volume overload, and the severity and duration of increases in
LV filling in response to cardiac functionl abnormality associated
with HF.
36
A plausible reason for the younger age at presentation for
HF in our study and many parts of Africa may be related to the
aetiology of the condition, which are conditions that present in
young and middle age (for example rheumatic heart disease and
cardiomyopathies). In addition, hypertension and related target-
organ damage present at a younger age in Africans and people
of African descent.
The dominance of de novo presentation of HF in our cohort
may be related to poorer long-term outcome of HF in our setting,
that is, few people are living with chronic HF. Another reason may
be because of poor or inadequate health education. Most often
patients do not keep to one health facility when they have chronic
illnesses such as HF. They often move from one facility to another
(including alternative healthcare facilities) seeking a cure.
The relatively low mortality rate in our cohort may be related
to the fact that the study was conducted in a cardiology unit and
may not reflect what happens in a general medical ward or in
private practice in the country. The clinical characteristics of our
patients may also be explanatory. Our subjects were younger
compared to the typical patients with HF in the Western world,
who are generally elderly.
The average length of hospital stay was longer in our setting
(9 days) compared to 6.1 days in the USA
28
and nine days in
Europe.
7
However it was shorter than the 21 days reported from
Japan.
37
It is possible that longer stay in hospital affords patients
the opportunity to recover well and get used to medications for
HF. HF outcome is generally better in Japanese patients compared
to other high-income countries.
7,8,10
Furthermore it is also possible that the aetiology of HF in
our cohort could have affected the outcome. Hypertension is
predominantly the major risk factor for HF in our cohort. Ischaemic
heart disease is relatively uncommon. It is well known that
mortality rates from coronary artery disease (CAD) are generally
worse than in those with non-ischaemic heart disease. Mitchell
et