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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 2, March/April 2021
AFRICA
75
heart rate variability, caused by autonomic dysregulation, and
post-infarction inflammatory and neurohormonal changes are
common among MI patients and have been shown to manifest
physically as mental and psychological changes of depression
and anxiety
33-38
and possibly are the cause of high adverse
outcomes reported among these patients.
49
Patients undergoing CABG probably generate an even greater
inflammatory response than PCI subjects since they generally
have more severe CAD affecting all three coronary arteries or
the left main coronary artery, compared to patients selected for
PCI who are more likely to have single- or two-vessel disease.
The higher prevalence of depression among CABG compared
to PCI subjects in our study could therefore have been related
to the severity of myocardial injury and the greater burden of
atherosclerotic disease in CABG participants (frequently triple-
vessel disease and heart failure compared to single- or double-
vessel involvement in the PCI group).
An important finding in our study was that LSM led to
a significant reduction in the prevalence of depression, from
51.0% pre LSM to 34.7% post LSM intervention. In addition,
we recorded a six-point reduction in the mean depression scores
post LSM (Table 3), indicating a reduction in the severity of
depressive symptoms with LSM intervention. After LSM,
depression was three times more frequent among CABG than
PCI patients (Table 5), suggesting that the PCI group benefited
more from the anti-depressive effect of LSM.
We attributed the marked difference in depression scores
in the PCI compared to the CABG group (7.90 vs 4.30 point
reduction, respectively) (
p
= 0.000) to early ambulation with
improvement in PA in the PCI group. It is noteworthy that PA
scores were similarly low for both CABG and PCI groups at
baseline (
p
= 0.119). There was a large increase in the PA scores
from a mean of 2.81 at baseline to 11.65 after LSM intervention
(Table 3). The PCI group attained higher PA scores compared to
the CABG subjects (
p
= 0.024) by the end of the study period
because of their more immediate mobility post revascularisation
(Table 5).
Although the prevalence of depression in partly compliant
participants fell after LSM intervention (51.0% at baseline to
33.7% post LSM), there was a marked reduction recorded in
LSM-compliant subjects (51.0% patients at baseline to 1.1% post
LSM) (
p
= 0.001). Also, a greater point reduction in depression
score was seen for subjects who adhered fully to LSM measures,
indicating a better reduction in severity of depressive symptoms
with LSM intervention (Table 4). An important finding in our
study was that fully compliant CABG and PCI patients derived
similar benefit from the LSM programme, emphasising the
role of adherence to LSM in reaping maximum benefit after
revascularisation, independent of the type of procedure.
The reduction in incidence and severity of depression
achieved in partly compliant participants was probably due
to modest increments in PA from baseline, without which
depressive symptoms may have persisted over time. This has been
highlighted by May
et al
. in their ground-breaking study, which
showed that depression status may not improve completely after
MI and is associated with a two-fold increased risk of death.
16
Our findings are consistent with previous studies, showing that
LSM improved mental functioning and reduced depression.
50-53
In a meta-analysis on mental health treatment and LSM
for improving clinical outcomes and incidence and severity
of depression among patients with CAD, Rutledge
et al
.
19
demonstrated that not only did LSM reduce depression to the
same extent as mental health treatment, but it was also superior
in reducing all-cause mortality risk. In another study, Carl
et al
.
13
established that LSM reduced depressive symptoms by 63% and
all-cause mortality by 73.0%.
While the adherence to LSM measures showed improvement
in dietary changes and cessation of cigarette smoking among
the majority of the participants, only 40.0% complied with
aerobic exercise recommendations; overall, only one-third of
subjects adhered fully to LSM. Poor compliance with LSM
recommendations has been reported in previous studies.
54,55
Similar to these studies, the reasons for non-adherence to
LSM measures in our study were mainly lack of motivation,
bodily discomfort and fear of an adverse outcome, although
no exercise-related adverse effects were reported among the
participants. Thoracic cage and lower limb discomfort as well as
fear of potentially adverse outcomes after early ambulation post
bypass surgery was another possible factor accounting for the
lower exercise scores among the CABG subjects. It is therefore
not surprising that twice as many PCI subjects participated in
frequent PA compared to the CABG group. This may explain the
higher prevalence and severity of depression after LSM among
the CABG group. This is an important limitation of our study,
which to some extent may have been averted if the interview
after the LSM intervention had been performed six months after
surgery instead of 12 weeks.
Limitations and strengths
Our study has methodological limitations and challenges.
Although subjects were prospectively evaluated, the convenient
non-random sampling method used in this study limited the ability
to generalise our findings to all CAD subjects. Only participants
undergoing revascularisation who were able to participate in the
LSM recommendations were recruited into the study. Participants
recruited were referred by state institutions, so that most
participants were from the lower income group. Furthermore, the
PA levels were self-reported and were not objectively verified at
follow up through stress testing. However, studies have shown that
self-reported activity has significant concordance with objectively
measured PA using actigraphy-assessed PA.
39,40
A further important consideration is that the 12-week period
after revascularisation might have been too short for assessing
the response to LSM in CABG patients since the operation
involved mediastinal surgery and lower-limb vein grafts, which
may have required a longer period of physical recovery before
full PA could be resumed, compared to PCI subjects who
were almost immediately ambulant after their procedure. A
re-evaluation after six months of LSM would have provided a
fairer comparison between the two groups.
The limited time frame of three months for the LSM
intervention in our study also does not permit long-term
inferences to be made from our findings since persistence of
depression over time has been reported by May
et al
.
16
Also,
a more informed assessment of the exercise parameters and
incidence of depression would have been obtained in subjects
matched for ejection fraction and disease severity. A longer-term,
randomised, controlled study is needed to verify our findings
and to relate these findings to haemodynamic severity of the