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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 28, No 6, November/December 2017
374
AFRICA
We calculated the predictive values of the ECG patterns
suggestive of right ventricular hypertrophy (RVH) or right atrial
enlargement (RAE) for the diagnosis of PH. Table 2 shows the
sensitivity, specificity and positive and negative predictive values
for the occurrence of PH. Sensitivity ranged between 6.2 and
47.7% while specificity ranged between 79.3 and 100%. The NPV
ranged between 81.5 and 88.9%. The PPV was lowest at 25% for
RBBB and QRS right-axis deviation (
≥
100°), and highest at
100% for QRS axis
≥
100° combined with R/S ratio in V1
≥
1 or
R in V1
>
7 mm.
We calculated the predictive values of the ECG patterns for
the diagnosis of indirect signs of PH (RVH or RAE) in patients
with PH. The sensitivity for predicting RVH and RAE were
relatively similar for all parameters, ranging from 2.1 to 56.3%
and 2.6 to 57.9%, respectively (Table 3). The specificity was
higher for both RVH and RAE for all parameters (all
>
60%). The
PPV was found to be higher for RVH than for RAE, for which
all parameters had values above 90%. The NPV was higher for
RAE than for RVH, but for both, it was relatively low (all
<
50%).
Discussion
The main findings from this study of the predictive value
of ECG abnormalities in patients with PH in SSA are the
following. A strictly normal ECG was exceptional, with the most
prevalent abnormalities being pathological Q wave, tachycardia,
QRS right-axis deviation and left ventricular hypertrophy. The
specificity of ECG abnormalities suggestive of PH was generally
high, but prevalence of those relating to right heart strain were
rather less frequent. Altogether, our findings suggest that on
their own, ECG abnormalities cannot discriminate patients
who are more likely to be diagnosed with PH via costly and
technically demanding examinations, nor can they reliably rule
out patients for whom such examinations should be withheld.
Previous studies of heart failure in SSA have reported
that a completely normal ECG is very rare in the presence of
heart disease.
18,19
In general, the ECG abnormalities have higher
specificity than sensitivity. The low sensitivity in our study
precludes the ECG from being sufficient for screening without
complementary tests, but the ECG is a simple, non-invasive
and inexpensive test to perform. It could be implemented in
screening protocols as a supplement to physical examination,
signs and symptoms, exercise test, chest X-ray and medical
history of predisposing factors such as chronic infections, chronic
obstructive pulmonary disease and congenital heart disease.
The specificity, as well as the NPV, was high for the parameters
indicating PH. Positive findings on an ECG could therefore
warrant further investigation with more advanced diagnostics.
The most useful parameters seemed to be QRS right-axis
deviation of more than 100° and R/S ratio in V1
>
1 or R wave
in V1
>
7 mm, especially when both were present.
Overall, the indirect ECG features of PH, namely RVH and
RAE, had high specificity and high PPV. Both were higher for
RVH than for RAE, possibly explained by the fact that RAE was
seen only in more advanced disease. Sensitivity and NPV were
lower, and the absence of ECG abnormalities indicating RVH or
RAE could not exclude their presence. The sensitivity of indirect
ECG features was, however, superior to direct ECG indication of
PH, suggesting that a positive ECG can point to RVH or RAE
better than to PH directly.
Previous studies have assessed the role of ECG in predicting
right ventricular dysfunction but not PH directly, therefore
offering less opportunity for comparison with our findings. A
study conducted in Canada showed that ECG abnormalities
suggestive of RVH were rare in patients with normal RVSP,
and had a high positive predictive value.
20
Although Henkens
et
al.
showed that ECG-derived ventricular gradient was superior
to conventional ECG parameters, QRS right-axis deviation,
suggesting chronically increased RV pressure load, was shown
to have a sensitivity and specificity of 84 and 96%, respectively.
21
Increased R/S ratio in V1 or increased R wave in V1 was
the best predictor for RVH and RAE, which is in agreement
with the results of Nagai
et al.
,
22
who found that increased R/S
ratio in V1 indicated right ventricular systolic dysfunction. Also
Table 2. Predictive values of ECG patterns suggestive of right ventricular
hypertrophy or right atrial enlargement for the diagnosis
of PH in the PAPUCO registry (RSVP
>
35 mmHg)
ECG criterion
Sensitivity
(%)
Specificity
(%)
Positive
predictive
values
(%)
Negative
predictive
values
(%)
QRS axis
≥
100°
38.5
94.7
62.5
87.1
Extreme axis deviation (QRS
>
190°)
6.2 100.0 100.0
82.4
R/S ratio in V1
>
1 or R in V1
>
7 mm 47.7
95.8
72.1
88.9
Definite right ventricular hypertrophy
30.8 100.0 100.0
86.4
• QRS axis
≥ +
100°; and
• R/S ratio in V1
≥
1 or R in V1
>
7 mm
Right bundle branch block and QRS
right-axis deviation (
≥
100°)
1.5
99.0
25.0
81.5
P
>
2.0 mm in lead II or
>
1.5 mm in
lead V1/V2, unchanged duration
36.9
79.3
28.9
84.6
Table 3. Predictive values of ECG patterns for the diagnosis of indirect signs of pulmonary hypertension
(right ventricular hypertrophy or right atrial enlargement) in patients with pulmonary hypertension from the PAPUCO registry
ECG criterion
Sensitivity (%)
Specificity (%)
Positive predictive values (%) Negative predictive values (%)
RVH RAE
RVH RAE
RVH
RAE
RVH
RAE
QRS axis
≥
100°
45.8
47.4
85.7
73.9
91.7
75.0
31.6
46.0
Extreme axis deviation (QRS
>
190°)
8.3
7.9
100.0
95.7
100.0
75.0
24.2
38.6
R/S ratio in V1
>
1 or R in V1
>
7 mm
56.3
57.9
78.6
65.2
90.0
73.3
34.4
48.4
Definite right ventricular hypertrophy
37.5
42.1
92.9
87.0
94.7
84.2
30.2
47.6
• QRS axis
≥ +
100°; and
• R/S ratio in V1
≥
1 or R in V1
>
7 mm
Right bundle branch block and QRS right-axis
deviation (
≥
100°)
2.1
2.6
100.0
100.0
100.0
100.0
23.0
38.3
P
>
2 mm in lead II or
>
1.5 mm in lead V1/V2,
unchanged duration
45.8
39.5
85.7
60.9
91.7
62.5
31.6
37.8
RVH, right ventricular hypertrophy; RAE, right atrial enlargement.