Cardiovascular Journal of Africa: Vol 30 No 1 (January/February 2019)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 1, January/February 2019 10 AFRICA
Teaching Hospital. Subjects were duly counselled about the
aims and objectives of the study. Written informed consent was
obtained prior to recruitment.
The bio-data of the subjects were obtained. A history was
taken and physical examination performed to ascertain the
diagnosis and aetiology of HF, to determine the patient’s
functional class and duration of illness, measure various
anthropometric indices, and screen for the exclusion criteria
mentioned above.
Transthoracic echocardiography was done with a
Sonoscape SSI-8000 machine and 3.5-MHz transducer
probe. Two-dimensional (2D) directed M-mode and Doppler
transthoracic echocardiography were performed in the
parasternal, apical and subcostal views on all 219 subjects.
The 2D directed M-mode measurements were done in
accordance with recommendations of the American Society of
Echocardiography (ASE) to determine LV chamber dimensions
and LV ejection fraction (LVEF). Right ventricular (RV)
longitudinal systolic function was assessed by the tricuspid
annular plane systolic excursion (TAPSE).10 2D parameters
of RV structure were also assessed. These included RV basal
diameter, right atrial area, RV wall thickness and eccentricity
index.11 Doppler echocardiography was performed to determine
pulmonary artery systolic pressure (PASP), LV diastolic function
and the severity of MR.
PASP was determined by the tricuspid regurgitant (TR) jet
method, using the ASE guidelines for assessment of the right
heart.11 The peak TR jet velocity (V) was measured by colour
Doppler guided continuous-wave Doppler in the apical four-
chamber view, parasternal RV inflow view and parasternal short-
axis view at aortic valve level. The highest velocity obtained from
any of these views was selected.
Right atrial pressure (RAP) was estimated from the size
and collapsibility of the inferior vena cava (IVC) by assigning
standardised values, recommended by the guidelines.11 The
estimated PASP was then calculated using the modified Bernoulli
equation:
PASP = 4V2 + RAP
A cut-off value of PASP > 36 mmHg, suggesting PH, was
employed in this study, based on the 2009 European Society of
Cardiology (ESC)8 and 2010 ASE11 recommendations. These
were the prevailing guidelines during the planning and execution
of this study.
LV diastolic function was assessed according to the ASE
guidelines,12 using transmitral Doppler velocities, left atrial
volume index, and tissue Doppler of the septal and lateral mitral
annulus. All Doppler measurements were taken at the end of
expiration, using the average of measurements obtained during
three consecutive cardiac cycles.
LV filling pressure was assessed using the E/e′ ratio (ratio
of the pulsed-wave transmitral E velocity and average tissue
Doppler e′ velocities). Diastolic dysfunction was graded as
normal, grade 1 (impaired LV relaxation), grade 2 (pseudo-
normal filling pattern with mild elevation in LV filling pressure)
or grade 3 (restrictive LV filling pattern and marked elevation in
LV filling pressure).
Severity of MR was assessed by calculating the mitral
regurgitant volume (MRvol) using the formula:
MRvol = SVmitral – SV LV outflow tract
13
where SVmitral is the mitral valve stroke volume and SV LV outflow tract
is the LV outflow tract stroke volume. MR severity was graded
according to the ASE guidelines13 as follows: mild (< 30 ml),
moderate (30–60 ml) and severe (> 60 ml).
Statistical analysis
Data were analysed using the Statistical Package for Social
Sciences version 17.0 (SPSS, Inc, Chicago, IL, USA). Normally
distributed numerical data are presented as means and standard
deviations, while the skewed ones are expressed as medians and
ranges. Categorical variables are presented as proportions.
Means were compared using the Student’s t- test. Categorical
variables were compared using the chi-squared test or Fisher’s
exact test when cell counts were less than five. Correlation
analyses were done to demonstrate associations between
pulmonary pressures and specific clinical and echocardiograhic
parameters. Pearson’s correlation was done for normally
distributed variables while Spearman’s rank correlation was used
for variables that did not meet normality assumptions. Forward
stepwise multiple linear regression analyses were performed
in order to determine the clinical and echocardiographic
parameters that were independently associated with PASP in
the study population.
Results
A total of 219 subjects with heart failure were recruited for this
study, comprising 132 males (60.3%) and 87 females (39.7%).
Mean age of the study population was 56 ± 15 years. Other
clinical characteristics of the study population are summarised
in Table 1.
The most common aetiology of HF in the overall study
population was hypertensive heart disease, which was found
in 107 (48.9%) subjects, followed by idiopathic dilated
cardiomyopathy, which occurred in 74 (33.8%) subjects. One
hundred and forty-six subjects (66.7%) had heart failure with
reduced ejection fraction (HFrEF), while 73 (33.3%) had heart
failure with preserved ejection fraction (HFpEF). The frequency
Table 1. Clinical characteristics of the study population (n = 219)
Parameters Mean ± SD/n (%)
Overall mean age in years 56 ± 15
Male 58 ± 14
Female 54 ± 15
Males 132 (60.3)
Females 87 (39.7)
Body mass index (kg/m2 ) 27.2 ± 5.6
Systolic blood pressure 117.0 ± 20.3
Diastolic blood pressure 75.0 ± 13.3
NYHA functional class
II 131 (59.8)
III 68 (31.1)
IV 20 (9.1)
Median NYHA functional class 2 (2–4)*
Median duration of HF (weeks) 52 (1–579)*
Previous hospitalisations
None 103 (47.0)
1 73 (33.3)
≥ 2 43 (19.7)
*Median (range); NYHA, New York Heart Association.