Download Full Text-1 - African Index Medicus

Vol. 20 No. 1, March 2005
Tanzania Medical Journal
1
CLINICAL AND ECHOCARDIOGRAPHIC STUDY OF HYPERTROPHIC CARDIOMYOPATHY IN
TANZANIA
EE Maro, M Janabi, R Kaushik and AA Amur
Summary
There are few published reports on Hypertrophic
Cardiomyopathy (HCM) in Africans. Due to lack of
echocardiography machines in most hospital centers, clinical
identification of HCM remains confined to those patients with a loud
heart murmur associated with the outflow gradient. Between June
1998 and October 2002, 134 patients were studied at Hindu Mandal
Hospital, 67.9% were male and 32.1% were female. Their mean age
was 54.8 + 14.2 years. The presenting symptoms were Dyspnoea
62.7%, Chest pain 55.9%, Palpitations 50.7% (Pre-syncope 21.6%,
Syncope 8.9%) Due to the diverse clinical features, only 8(5.9%)
patients had a correct diagnosis of Hypertrophic Cardiomyopathy in
their echocardiography request forms. Others were diagnosed as
Ischaemic heart disease 31.8%, Dilated Cardiomyopathy 29.9%,
Mitrol valve prolapse 11.2% and Arrhythmias 6.7%. Using
Echocardiography, the pattern of LVH among these patients was
found to be: Asymmetrical septal hypertrophy in 50.7% and apical
hypertrophy in 3.0%. The important role of echocardiography in
diagnosis is stressed with a plea for the increasing availability of this
non-invasive technique for early and accurate diagnosis of
Hypertrophic Cardiomyopathy.
Key words: Echocardiography: Hypertrophic
Cardiomyopathy
Introduction
Hypertrophic Cardiomyopathy (HCM) is defined as the
presence of a hypertrophied non-dilated left ventricle in
the absence of cardiac or systemic diseases capable of
producing significant hypertrophy.(1-3) It occurs worldwide
with a prevalence of between 0.1% and 0.2%, two thirds
of cases occur sporadically and one third of them have
familial autosomal dominant transmission.(4) HCM has
been a frequent source of frustration to clinicians and their
patients due to its diverse pathophysiology and
heterogeneous clinical spectrum as well as its therapeutic
uncertainties.(5) Among Africans, there are few published
reports of Hypertrophic Cardiomyopathy.(7) Among
Caucasian population, HCM has a mortality rate of
between 2 and 4% and sudden death which occurs
frequently during or just after vigorous physical activities
accounts of 30% of the cases.(6)
Before the advent of echocardiography, clinical
identification of HCM was virtually confined to those
patients with a loud heart murmur (associated with the
outflow gradient). Consequently at that time the
obstructive form seemed to represent virtually the entire
clinical spectrum and the subortic gradient was often
identified with the disease itself.(8) This remains true up
todate in the developing countries of Sub-Saharan Africa
where echocardiography machines are not available in
most hospital centers. Echocardiography is the noninvasive method of choice for evaluating HCM.
Correspondence to: Maro E, P. O. Box 65202, Muhimbili University College of
Health Sciences, Dar es Salaam.
Dept. Internal Medicine, Muhimbili University College of Health Sciences
We know that most HCM patients have the nonobstructive form(1,2,6) and in many patients the outflow
gradient is compatible with normal longevity in the
absence of significant symptoms.(1,3,8,9,10) The objective of
this study was to determine the demographic features of
our HCM patients as well as their echocardiographic
features.
Methodolgy
Between June 1998 and October 2002, 6880 patients
belonging to various racial of ethnic origins from
Muhimbili National Hospital, Dar es Salaam were referred
to Hindu Mandal Hospital for echocardiogram. Among
these patients 134 (0.19%) patients with Hypertrophic
Cardiomyopathy (HCM) were consecutively and
prospective studied. The other patients had Rheumatic
Heart Diseases (29.01%), Congenital Heart Diseases
(including mitral valve prolapse) 25.83%), Dilated
Cardiomyopathy 6.11%, Pericardial diseases 11.39%,
hypertensive heart disease 4.72% and other 8.30%. HCM
was defined using echocardiography as hypertrophied non
dilated LV in the absence of another cardiac or systemic
disease capable of producing a comparable magnitude of
LV.(8,9,11)
All patients were interviewed by experienced
cardiologist about their age, onset on cardiovascular
symptoms and diagnosis, the presence of or absence of
symptoms including chest pain, palpitations, loss of
consciousness, pre-syncope, shortness of breath on
exertion, exercise limitations, and family history of HCM
or sudden cardiac death.
Physical examination included measurement of
height, weight and blood pressure. Blood pressure was
measured twice on the right arm and with a mercury
sphygmomanometer after 10 minutes of bed rest with a 2
minute interval.
The latter value was used in statistical analysis. 12
lead ECG and baseline laboratory studies were performed
including M-Mode Echocardiogram, 2 dimensional
echocardiography, Doppler and Colour flow mapping. A
24 hour Holter ECG was done in some patients. The 12
lead ECG recorded at presentation was evaluated for
rhythm disturbances and conduction disease including
atrioventricular block and intraventricular conduction
delay, Sokolow-Lyon criteria was used as a measure of
LVH.(11)
Echocardiographic evaluation was performed with a
Hewlet-Packerd Sonos 1000 scanner with a 2.5 MHz
transducer. Patients were imaged while in a left lateral
position in the echocardiography laboratory. Twodimensional and M-Mode echocardiographies were
performed using conventional technique(10), LV wall
Vol. 20 No. 1, March 2005
Tanzania Medical Journal
2
thickness was recorded, where possible, at mitral valve
and papillary muscle level in the anterior and posterior
septum and in the lateral and posterior LV walls using
short axis, two-dimension images. Anterior and posterior
wall thickness at the apex was measured in the fourchamber apical view. Measurement of septal thickness,
maximal end diastolic (EDD) and end-systolic (ESD)
dimensions and LV ejection fraction as well as left atrial
size were performed according to the recommendations of
the American Society of Echocardiography(12) Left atrial
was considered enlarged if the diameter was >40mm.
Colour guided continuos wave Doppler was performed in
the apical view to determine the peak LV outflow tract
gradient with care taken to avoid contamination of MR jet.
Also Doppler recordings of blood velocity at the apical,
midventricular and mitral valve area were performed.
Significant LVOT obstruction was considered present
when the peak instantaneous gradients was >30mm Hg.
Seventy two, age and sex matched control subjects
were chosen. These were asymptomatic individuals who
came for medical examination before travelling abroad to
join learning institutions. They all had echocardiography
examination done in the same way as the patients. All the
study subjects signed informed consent forms before the
study and the study protocol was approved by the research
Council of our institution.
to 91 years (mean 54.8 14.2 years) Ninety one (67.9%)
patents were male and 43 (32.1%) were female.
A total of 119 (88.8%) were symptomatic at the first
presentation. The main symptoms were; Dyspnoea
84(62.75), chest pain 75 (55.9%), pre-syncope 29 (21.6%)
and syncope 12 (8.9%). In 10 of these 119 symptomatic
patients, the first manifestation was a morbid events
including congestive heart failure (n-4 (3.34%) and atrial
fibrillation (n = 12 (8.9). Two patients with atrial
fibrillation presented with concomitant embolic events
(TIA, Stroke). The asymptomatic patients (11.2%)
presented with incidental findings such as an abnormal
ECG (n = 6) a new undiagnosed murmur (n=5), and
abnormal echocardiography performed during evaluation
for a major operation (n = 4) table 1.
Definitions
The diagnosis of HCM was based on demonstration
of maximal LV wall thickness of at least 15mm on 2
dimensional echocardiograph in the absence of other
causes of LVH such as hypertension. Subjects were
defined as having hypertension if systolic BP was above
160 mmHg or diastolic BP above 95 mmHg or if the
subject was receiving treatment of hypertension. Also
those who had a body mass index (BMI) >35kg/m2 were
excluded. Asymmetrical septal hypertrophy was defined
as a septal to posterior LV free wall ratio of greater that
1.5.
The diagnostic criteria for apical Hypertrophic
Cardiomyopathy included demonstration of asymmetric
LVH confined predominantly to the LV apex with an
apical wall thickness >15mm and a ratio of maximal
apical to posterior wall thickness >1.5 based on two
dimensional echocardiography.
Stastistical Analysis
All data are expressed as mean standard deviation.
Statistical differences between groups were determined by
unpaired T–tests. Paired T-test were used to analyse
differences in paired data. A p value less than 0.05 was
considered significant.
Results
One hundred and thirty four patients with HCM were
consecutively and prospectively studied from June 1998
to October 2002. The age of these patients ranged from 22
Table 1. Clinical and Electrocardiogtaphic Characteristics
of
the 134 patients with HCM.
Characteristic
No. of Patient (%) N= 134
Age (Years)
Mean age
Range
54.8  14.2
22 – 91
Gender
Mean
Women
91 (67.9%)
43 (31.1%)
Cardiac Symptoms
Dyspnoea
Chest Pain
Palpitations
Pre-Syncope
Syncope
No symptoms
Duration of Symptoms (yrs)
History of Cardiac Failure
Family History of (HCM)
Sudden Death
84 (62.7%)
75 (55.9%)
68 (50.7%)
29 (21.6%)
12 (8.9%)
15 (11.2%)
2.1  2.0
11 (8.2%)
14 (10.4%)
21 (15.7%)
Clinical Signs
Heart rate (beats/min)
Systolic/Diastolic Blood Pressure (mmHg)
S4 audible
Systolic murmur
67 16
131  14/80  4
75 (55.9%)
88 (65.7%)
Chest X = Ray
Cardiothoracic Ratio (%)
Range
50  6
41 – 62
Electrocardiographic Findings
Left Ventricular Hypertrophy
Left Atrial Enlargement
Right Ventricular Hypertophy
Atrial Fibrillation
Pathological Q wave
T wave Inversion
Intraventricular Conduction Block
Giant T wave > 10mm
Normal
92 (68.7%)
20 (14.9%)
12 (8.9%)
34 (25.4%)
101 (75.4%)
5 (3.7%)
9 (6.7%)
3 (2.2%)
16 (11.9%)
Data presented are mean value  SD or number (%)
of
patients
with
HCM
(Hypertrophic
cardiomyopathy).Only 14 (10.4%) patients were known to
have family history of HCM and 21(15.7%) patients had
an associated family history of sudden death. The duration
of symptoms was 2.1.  2.0 years. Due to diverse clinical
features of HCM majority of the patients had wrong
diagnoses on their referral notes to our echocardiography
laboratory, 40(29.9%) patients were diagnosed as having
dilated cardiomyopathy, 42 (31.3%) as having ischaemic
heart disease, 15(11.2%) as having mitral valve prolapse
Vol. 20 No. 1, March 2005
Tanzania Medical Journal
and 9(6.7%) as having arryhmias. Only 8(6.7%) patients
had a correct diagnosis of hypertrophic cardiomyopathy.
A variety of abnormal patterns and abnormalities were
evident on the 12 – lead ECG either alone or in
combination as shown in table. Ninety two (68.7) patients
had left ventricular hypertrophy and 16 (11.9%) had
normal ECG. Atrial fibrillation was present in 12 patients
including 2 who presented with an embolic stroke. The
thickness of intraventricular septum was 2.10.4 and the
LV posterior wall thickness was 1.40.6 and thus the ratio
of septum to posterior wall 1.90.5. The LV septal
thickness, posterior wall thickness and left atrial diameter
were significantly greater in patients with HCM than in
control subjects (p=0.001). However LV end diastolic
diameter and LV diastolic function was significantly
impaired among HCM patients than the control group (p =
0.0001) Table 1.
Of the 134 patients studies, 68(50.7%) had
asymmetrical septal hypertrophy (ratio >1.5:1) 47 (35.1%)
had concentric hypertrophy; 15(11.2%) had hypertrophy
of the LV posterior wall and 4(3.0%) had hypertrophy
confined to the ventricular apex. Based on continuous
wave Doppler examination, 38(28.4%) patients had
subaortic obstruction under basal condition (peak
instantaneous outflow gradients of 4832mmHg). Mitral
regurgitation was identified by colour flow imaging in
88(65.7%) and was judged as mild in 52 patients and
moderate in 36 patients.
Table 2. Elechocardiographic findings in 134 patients
with
HCM and 72 control subject
Parameter
HCM
N = 134
54  14.2
4.7  0.6
Control
Subjects
48.0 11.1
4.5 0.4
2.8  0.5
2.1 0.4
1.4  0.6
1.9  0.5
44  0.6
72  9
42  8
2.6  0.3
1.0  0.1
0.9  0.2
1.0 0.1
3.5  0.2
67  10
38  6
NS
0.001
NS
0.001
0.05
NS
NS
 Doppler diastolic indexes
Peak E wave velocity (cm/sec)
Peak A wave velocy (cm/sec)
E/A wave velocity (cm/sec)
LV outflow tract obstruction at rest 30 mmHg
LV outflow tract gradient (mmHg)
V-max (M/sec)
Systolic anterior motion of mitral valve
40  7
71  7
0.6  0.5
38 (28.4%)
48 32
2.0  1.5
41 (30.6%)
75  4
2.9  6
2.4  0.2
0.05
0.001
0.0001
 Location of maximal hypertrophy
Septum
Concentric
LV posterior wall
Apical hypertrophy
68 (50.7%)
47 (35.1%)
15 (11.2%)
4 (3.0%)
 Age
 LV end – diastolic diameter (cm)
LV end – systolic diameter (cm)
Intraventricular septum thickness (cm
LV posterior wall thickness (cm)
Septum/posterior wall ratio
Left atrial diameter (cm)
LV ejection graction (%)
Fractional shortening (%)
P.Value
NS
NS
Data presented are mean value  SD or number (%) of patients with hypertrophy
Cardiomyopathy (HCM)

LV = Left Ventricular

V – max = Maximum flow velocity in the LV outflow tract.
Discussion
Hypertrophic Cardiomyopathy (HCM) is a primary
cardiac disease with diverse clinical and genetic
expression and varied clinical course.(2,3,5,6,8,9) This disease
3
was first described in the late 1950. It was once thought to
be a rare disease by the medical practitioners in
developing countries. This is no longer true. In a used
selected hospital based patient population evaluated for
heart disease the prevalence of HCM was 1:500
(0.17%).(26) There was a predominance of male in our
study (67.9%). Other studies have shown the same.(14) The
duration of symptoms among our patients was 2.1+2.0
years. Among patients with symptoms 51 (38%) patients
were asymptomatic until they were 60 or more years of
age. Indeed our patients were of relatively advanced age,
with only 9 (6.7%) patients who were less than 30 years
old. The average age of the patients was 54.8  14.2 years.
These observations underlie the importance of recognizing
HCM as a disease compatible with advanced age and
normal longevity. Our oldest patient was 91 year old.
Such a perception is largely unappreciated in the available
HCM published data.(2,6,9)
The majority of our patients (85.8%) had
cardiovascular symptoms. The commonest symptoms
were; Dyspnoea (at rest or on exertion), 62.7%, Chest pain
(angina or atypical angina 55.9%, Palpitations 50.7%, Presyncope 21.6% and Syncope 8.9%) Due to the diverse
clinical features, three quarters of the patients faced a
delay between the initial presentation to a primary care
provider and the final diagnosis of HCM. This was caused
by the misinterpretation of chest pain, Dyspnoea and T
wave changes in the ECG as features of coronary artery
disease. According to the echocardiography request forms,
only 8 (5.9%) patients had a correct diagnosis of HCM.
The others were diagnosed as having; Ischaemic heart
disease 42 (31.3%) patients, Dilated Cardiomyopathy 40
(29.9%) patients, Mitral valve prolapse 15 (11.2%) and
Arrhylhmias 9 (6.7%) patients. The correct diagnosis of
HCM is of major importance because many of these
patients with diverse clinical presentation tend to land in
Intensive Care Units for suspected acute myocardial
infarction.
Echocardiography is the non-invasive method of
choice for the diagnosis of HCM.(11) With M-mode, 2dimensional echocardiography and Doppler studies it is
possible to quantitatively evaluate the degree of local
septal thickness, distribution of hypertrophy and extension
and size of the LV outflow tract.(12) The magnitude and
extent of LV hypertrophy, in the 134 HCM patients, was
comparable with those of a previously reported tertiary
center HCM population(13) With respect to the pattern of
LV hypertrophy Asymmetrical septal hypertrophy was
present in 50.5% of the patients, concentric in 35.1% LV
posterior wall in 11.2% and Apical in 3.0%. The typical
feature of Apical HCM first described by Sakamoto(13)
and Yamaguchi(14) and their associates consists of LV
apical hypertrophy echocardiographically as well as
“giant” T wave negativity in the electrocardiograms. Our
4 patients with Apical HCM had maximal T wave
negativity most frequently in leads V4 and V5.
Cardiac function in HCM is characterised by
hyperdynamic systolic function and impaired diastolic
performance.(2) This study revealed that LV systolic
function were similar between HCM patients and the
Vol. 20 No. 1, March 2005
control group. However, the diastolic funtion of HCM
patients were significantly impaired that the control group
(p = 0.0001). Previous studies had shown that the patients
with HCM had a slow and delayed early filling of LV
with greater dependency on atrial contribution for
maintenance of stroke volume, hence impaired diastolic
function. The proportion of patients with obstructive form
of HCM with LV outflow tract gradients (>30mmHg) was
28.4%. This was similar to that generally report on the
disease.(3)
Morbid events occurs among HCM patients. The
most frequent events in our study were atrial fibrillation
(n=12) and heart failure (n=4) Atrial fibrillation occurred
in 8.9% of the patients and two patients had TIA/stroke
due to embolic etiology. Atrial fibrillation is a common
arrhythmia in HCM (17.30%) and is a major determinant
of stroke and other peripheral vascular events(13) Left
atrial enlargement on the baseline echo was the only
predictor of atrial fibrillation. Impaired LV relaxation in
patients with HCM has been previously proposed as a
mechanism for progressive left atrial enlargement and
subsequent atrial fibrillation.(5) Therefore patients with
HCM and atrial fibrillation presents a vulnerable subset in
which more than 30% develops events of embolic
etiology.
In conclusion Echocardiography has a important role
in the diagnosis of hypertrophic cardiomyopathy. (14) A
plea is therefore made for the increasing availability and
use of this non-invasive technique, (ideally suited for our
environment and readily acceptable to our patients) for
early and accurate diagnosis. Africans are reluctant to
allow autopsy, and thus echocardiography not only will
enable early diagnosis and therefore early treatment but it
will also allow a true assessment of the incidence of this
disease in our area.
Tanzania Medical Journal
4
Rereferences
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Gavis M,J. Hypertrophic Cardiomyopathy: One disease or several Br. Heart
J. 1990 63(5): 263-4.
Maron BJ, Bonow RO, Cannon RO, Leon MB, Epstein SE. Hypertrophic
Cardiomyopathy: Interrelation of clinical manifestations, pathophysiology
and therapy. . Engl J Me 1987; 316:780-9, 844 – 52.
Maron BJ, Hypertrophic Cardiomyopathy. Lancet 1997; 350: 127 – 33.
Frank S, Braunwald E. Idiopathic hypertrophic subaortic stenosis: Clinical
analysis of 126 patients with emphasis on the natural history. Circulation
1968; 37: 759 – 88.
Okuwobi BO. Hemodynamic and angiographic features of Nigerian
Cardiomyopathies Myocardiology in Africa 1974; 1: 57.
George BO, Okuwobi Bo, Talabi Aj, Jaiyeola BA. Hypertrophic
Cardiomyopathy in Nigerians. Trop. Cardial 1981; 17 926): 68 – 75.
Wigle ED, Heimbecker RO, Guntoa RW. Idiopathic ventricular septal
hypertrophy causing muscular subaortic stenosis Circulation 1962; 26: 325 –
40.
Cannan CR, Reeder GS, Bailey KR et al. Natural history of Hypertrophic
Cardiomyopathy. A population based study 1976 through 1990. Circulation
1995; 92: 2488 – 95.
Maron BJ Gottdiener JS, Epstein SE. Patterns and significance of distribution
of Left Ventricular Hypertrophy in Hypertrophic Cardiomyopathy. A wide
angle two-dimensional echocardiographic study of 125 patients. Am. J
Cardiol 1981; 48: 418-28.
Sokolow M, Lyon TP. The ventricular complex in left ventricular Hypertophy
as obtain by Unipolar precordial and limb leads, Am Heart J 1949; 37: 161 –
86.
Sakomot T, Tei C, Murayama M, et al. Giant T wave inversion a
manifestation of Asymmetrical septal hypertrophy (ASH) of the left ventricle:
Echocardiographic and Ultrasono – Cardiotomographic study. Jpn Heart J
19776; 17: 611-29.
Yamaguchi H, Ishimura T, Nishiyama S, et al. Hypertrophic nonobstructive
Cardiomyopathy with giant negative T wave (apical Hypertrophy)
ventriculographic and echocardiographic feature in 30 patients. Am J
Cardiol. 1979; 44: 401 – 12.
Olivotto J, Cecchi F, Casey AS, Dolarra A, Treverse JH, Maron BJ. Impact of
atrial fibrillation on the clinical course of hypertrophic cardiomyopathy.
Circulation 2001; 104: 2517 – 24.
Thorvalden, P Asplund K, et al. Stroke incidence, case fatality and mortality
in the WO MONICA report. World Health Organization Minitoring Trens
and Determinants in Cardiovasular Disease. Stroke 1995;26: 361-7.