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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 31, No 4, July/August 2020
AFRICA
181
measurements were performed according to the American
Society of Echocardiography (ASE) chamber guidelines
4
by
two accredited readers, S Nel and F Peters. Left ventricular
end-diastolic volumes, end-systolic volumes and left ventricular
ejection fraction (LVEF) were measured using the Simpson
method. Measurements relating to left ventricular diastolic
function were performed as per the ASE guidelines on diastolic
function and included pulse-wave Doppler at the mitral tips
and tissue Doppler of both medial and lateral mitral annuli.
5
Measurements relating to the right ventricle were based on ASE
guidelines on the right ventricle.
6
Echocardiography was used to
specifically diagnose ILVNC, dilated cardiomyopathy (DCMO)
and hypertrophic cardiomyopathy (HCM) based on predefined
criteria (Table 1).
Continuous variables are summarised as the mean ± standard
deviation as appropriate. Categorical variables are presented as
frequencies and percentages. Sensitivity, specificity, positive and
negative predictive values, and the likelihood ratio for a positive
or negative test for ECG against echocardiography as the gold
standard were calculated with their 95% confidence interval.
Results
The baseline characteristics of all family members screened
are summarised in Table 2. A total of 83 close relatives of 38
unrelated patients with ILVNC accepted our invitation for
screening. Pre-existing hypertension was found in 11 (13.2%)
of the screened members. With regard to these 11 family
members, two had a history of previous cerebrovascular
accident. The majority of family members who were screened
were asymptomatic. However, three were symptomatic with two
having New York Heart Association (NYHA) class II dyspnoea
and one being in NYHA class III.
A total of 83 ECGs were performed, with 61 (74.5%) subjects
having a normal ECG (Table 3). Abnormal findings were
observed in 22 subjects (26.5%). In 16 of the 22 subjects, left
ventricular hypertrophy (LVH) was detected (72.7%). Only one
of these subjects with LVH had pre-existing hypertension.
Echocardiographic screening revealed unexplained left
ventricular dysfunction in 10 (12.05%) of the cohort of relatives
screened (Table 4). Of the 10 participants with unexplained LV
dysfunction, one had pre-existing hypertension, and nine had no
known pre-existing cardiovascular abnormalities. The remaining
nine individuals satisfied the criteria for the diagnosis of dilated
cardiomyopathy. None of the participants met any of the criteria
for ILVNC, HCM or hypokinetic DCMO. Six of these subjects
diagnosed with DCMO were asymptomatic whereas two were
in NYHA class II and one was in NYHA class III. Three of
the nine individuals diagnosed with DCMO were from the same
family.
A comparison between a strategy of clinical and ECG
screening only versus echocardiographic findings (Table
5) revealed that 61 (73.5%) subjects had a normal clinical
evaluation and a normal ECG. Within this group, abnormal
echocardiograms were found in seven (11.5%) subjects. The
echocardiographic abnormalities found were six subjects had
DCMO and one had unexplained LV dysfunction but did not
meet the criteria for DCMO, HCM or LVNC.
Table 1. Diagnosis of ILVNC, DCMO and HCMO
ILVNC
A combination of the echocardiographic criteria of Oechslin
et al
.
3
and Stöllberger
7
were used for the diagnosis of ILVNC in this study.
These criteria have previously demonstrated the ability to distinguish normal individuals from subjects with ILVNC in a sub-Saharan Afri-
can population. A diagnosis of ILVNC was made when all four of the following criteria were present:
• A ratio of non-compacted to compacted myocardium > 2 when measured at end-systole
• The presence of more than three prominent trabeculations in the left ventricular apex that did not originate from the septum
• Deep intertrabecular recesses that filled with blood from the ventricular cavity as visualised on colour Doppler ultrasound
• No evidence of congenital or acquired heart disease
DCMO
Left ventricular or biventricular systolic dysfunction and dilatation that is not explained by abnormal loading conditions or coronary artery
disease. LVEF < 45% associated with left ventricular dilatation
8
Hypokinetic non-dilated
cardiomyopathy
Left ventricular or biventricular global systolic dysfunction without dilatation (defined as LVEF < 45%), not explained by abnormal loading
conditions or coronary artery disease
8
HCM
The presence of left ventricular wall thickness ≥ 15 mm in one or more left ventricular myocardial segments with no other haemodynamics or
metabolic cause
9
ILVNC: isolated left ventricular non-compaction, DCMO; dilated cardiomyopathy, HCM: hypertrophic cardiomyopathy.
Table 2. Baseline characteristics of screened
non-compaction cardiomyopathy relatives
Patients (
n
)
83
Age at presentation (years)
30.7 ± 15.3
Females,
n
(%)
46 (55.2)
Pre-existing hypertension,
n
(%)
11 (13.2)
Systolic blood pressure (mmHg)
127 ± 21
Diastolic blood pressure (mmHg)
78 ± 14
Heart rate (beats/min)
76 ± 15
Connection,
n
(%)
Parent
9 (10.8)
Sibling
29 (35.0)
Child
41 (49.4)
Other*
4 (4.8)
NYHA class,
n
(%)
I
80 (95.4)
II
2 (3.4)
III
1 (1.2)
*Other: niece, nephew, aunt or uncle. NYHA: New York Heart Association.
Table 3. ECG characteristics of screened non-compaction
cardiomyopathy relatives
Patients (
n
)
83
Sinus rhythm,
n
(%)
83 (100)
Heart rate (beats/min)
76 ± 15
Abnormal axis,
n
(%)
3 (3.6)
Left
2 (66.7)
Right
1 (33.3)
Bundle branch block
1
LBBB
0
RBBB
1
Left ventricular hypertrophy,
n
(%)
16 (19.3)
(Sokolow–Lyon criteria)
LBBB: left bundle branch block, RBBB: right bundle branch block.