CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 6, July 2012
AFRICA
327
12-lead ECG correlated with persistently poor LV systolic
function at six months. T-wave inversion also correlated with LV
systolic function at baseline.
Typically, LV systolic functional recovery in PPCM is a slow
and drawn-out process that enters the second year of treatment.
2
On this basis, while LVEF in those patients subjected to
six-month follow up improved overall, just under half still had
defined impaired LV dysfunction, and this represents a major
therapeutic target for treatment. Therefore, long-term follow
up using the ECG in PPCM might well show ECG reversal
to normality as late as 18 months after first diagnosis, as our
long-term echocardiographic data suggest.
8
Moreover, we have
identified potentially useful markers (i.e. major T-wave inversion
and/or ST-segment depression on the 12-lead ECG) as simple but
important prognostic markers that might trigger more intensive/
aggressive treatment and follow up in PPCM cases.
Our findings and the overall utility of the 12-lead ECG in this
clinical setting require careful interpretation when fundamental
investigations such as echocardiography remain inaccessible to
most hospitals and patients in sub-Saharan Africa. Serum levels
of NT-proBNP are known to strongly predict the degree of heart
failure,
12
yet this test is still not available in most referral hospitals
in Africa where PPCM is prevalent. Surprisingly, because of vast
differences in sensitivity and specificity in detecting HF, it has
been suggested that the overall cost-effectiveness of measuring
serum NT-proBNP becomes comparable to that of screening for
HF using the 12-lead ECG alone,
25,26
due mainly to the relatively
low specificity of the 12-lead ECG.
26
The scarcity of the serum NT-proBNP test in our setting
almost mandates using something as inexpensive and easy as
the 12-lead ECG to screen for PPCM, even if its sensitivity and
specificity prove to be imperfect. These data will be particularly
useful if (after comparing ECG patterns in healthy African
women, derived from the Heart of Soweto cohort
27
) the 12-lead
ECG has the potential to be applied as a ‘rule-out’ test (i.e.
high specificity to identify all truly negative for PPCM cases).
Unfortunately, the ability to combine 12-lead ECG with typical
symptoms of HF (to increase its accuracy in detecting PPCM)
is confounded by their parallel presence in the late stages of
pregnancy (but not typically post-partum).
As indicated, our data suggest that baseline major T-wave
abnormalities were associated with poorer LV systolic function
at baseline, and, alongside baseline ST-segment depression, they
were also associated with persistent LV systolic dysfunction in
the short to medium term (i.e. six months). In Western countries,
major ST-segment depression and T-wave abnormalities are
often regarded as indications of myocardial ischaemia, bearing
consistent prognostic significance for cardiovascular disease
mortality across prospective studies, especially for men.
28
We remain wary of the fact that gender differences in ECG
findings often show women to have a higher prevalence of
ST-segment depression or T-wave changes, such as to question
the true significance of any association between ST-segment
depression and T-wave abnormalities with coronary heart disease
(CHD) mortality in women.
28
However, we are greatly reassured
by the number of large, population-based studies that show major
TABLE 4. COMPARING BASELINEAND SIX-MONTH ECG CHARACTERISTICS IN
44 PPCM PATIENTSWITH FOLLOW-UP DATA
Baseline
% of population
6-month follow up
% of population
p
-value
Rate and rhythm Mean heart rate (beats/min)
±
SD
104
±
18
77
±
14
<
0.001
Proportion in sinus rhythm
84 (95% CI: 70–93)
66 (95% CI: 50–80)
0.049
Proportion with sinus tachycardia
48 (95% CI: 32–63)
7 (95% CI: 1–19)
<
0.001
Proportion with arrhythmias
• premature ventricular complex
• sinus arrhythmias
2 (95% CI: 0.06–12)
7 (95% CI: 1–19)
2 (95% CI: 0.06–12)
27(95% CI: 15–43)
1.0
0.011
Axis
Proportion with QRS axis being:
• abnormal
• left axis
• right axis
• indeterminate
36 (95% CI: 22–52)
18 (95% CI: 8–33)
11 (95% CI: 4–25)
7 (95% CI: 1–19 )
14(95% CI: 5–27)
7 (95% CI: 1–19)
5 (95% CI: 0.6–15)
2 (95% CI: 0.06–12)
0.014
0.107
0.237
0.306
Conduction
Proportion with bundle branch block (BBB)
• left BBB
• right BBB
20 (95% CI: 10–35)*
9 (95% CI: 3–22)
2 (95% CI: 0.06–12)
18 (95% CI: 8–33)
9 (95% CI: 3–22)
2 (95% CI: 0.06–12)
0.787
1.0
1.0
Repolarisation
Proportion with T-wave abnormalities
• major
• minor
45 (95% CI: 30–61)**
30 (95% CI: 17–45)
16 (95% CI: 7–30)
27(95% CI: 15–43)
34 (95% CI: 20–50)
9 (95% CI: 3–22)
0.123
0.647
0.334
Proportion with ST-segment changes
• major ST changes
• minor ST changes
• ST-segment elevation
0
2 (95% CI: 0.06–12)
2 (95% CI: 0.06–12)
0
0
0
–
0.315
0.315
Hypertrophy
Proportion with left ventricular hypertrophy
[Defined by Minnesota Codes III
1
and (IV
1-3
or V
1-3
)]
7 (95% CI: 1–19 )
7 (95% CI: 1–19 )
1.0
Atria
Proportion with atrial abnormalities
• left atrium
• right atrium
• bi-atrial
20 (95% CI: 10–35)**
5 (95% CI: 0.6–15)
9 (95% CI: 3–22)
7 (95% CI: 1–19 )
9 (95% CI: 3–22)
2 (95% CI: 0.06–12)
7 (95% CI: 1–19)
0
0.133
0.557
0.694
0.078
*This sum exceeds that of individual BBB as some patients manifested incomplete BBB (either left or right).
**This sum exceeds that of individual sub-categories as some patients manifested features of each sub-category.
