Cardiovascular Journal of Africa: Vol 32 No 3 (MAY/JUNE 2021)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 32, No 3, May/June 2021 AFRICA 121
stroke would not receive anticoagulant therapy. This number
was surprisingly high and raised questions about the use of
the CHADS2 score as an independent risk-stratification tool.
However, with the development of the L2CHADS2 scale, only
four subjects (11.4%) with a zero or one point score developed
a LA/LAA thrombus. There were 231 (44.4%) subjects with a
CHA2DS2-VASc score of two points or more, but these patients
did not have a LA/LAA thrombus. This means that almost half
of these patients would have unnecessarily been exposed to
oral anticoagulation. In contrast, use of the L2CHADS 2 score
would have minimised this number and reduced the risks of
haemorrhage from unnecessary anticoagulant therapy.
Compared to the CHADS2 and CHA2DS2-VASc score,
the thrombosis incidence in the low- and intermediate-risk
subjects, retrospectively identified by the L2CHADS2 score,
was significantly lower, and in the high-risk group it was
significantly higher. This was in accord with the expectations
of a thromboembolic risk-stratification system, with higher
scores predicting higher incidence of LA/LAA thrombosis. Risk
scores based on the CHADS2 and CHA2DS2-VASc scales had
obvious limitations in our study. It therefore supported the use of
modified risk scores and the need for further prospective studies
on risk stratification in patients with NVAF.
The R2CHADS2 score posits that renal dysfunction is an
important predictor of stroke and peripheral embolism in NVAF
patients with intermediate and high stroke risk, and is based on
the ROCKET-AF and ATRIA stroke risk studies proposed in
2013.33,34 But in our study, a significant independent effect of
renal dysfunction on LA/LAA thrombus was not documented,
and so the relationship between them was not explored further.
The results of the present study indicated that we could
improve the accuracy of LA/LAA thrombus prediction if we
simultaneously considered LAA morphology. In addition, renal
dysfunction, a significant risk factor for bleeding, was added
to the R2CHADS2 scoring scheme that is intended to estimate
the risk of thromboembolic events and guide antithrombotic
therapy, which may not be appropriate.
The causes and mechanisms of atrial thrombi are not
completely equivalent for every patient with NVAF, so the
benefits of anticoagulant therapy may depend on the potential
stroke risks themselves, and therefore the risk/reward ratio of
different people may need comprehensive assessment to make
optimal decisions regarding anticoagulant therapy. This is one
reason why it can be relatively difficult to make decisions about
the use of anticoagulation in patients with NVAF. Therefore, if
we could develop objective criteria to assess the risk of stroke
in NVAF patients and guide the use of anticoagulants in this
population, it would be a good step forward.
Study limitations
This was a single-centre retrospective study of a limited number
of NVAF patients, with only 35 having LA/LAA thrombus. In
addition, the patients with NVAF in the study were refractory
to pharmacotherapy. Their general physical condition was
relatively good and they could tolerate radiofrequency ablation
or cardioversion. Even in those with a history of stroke, the
symptoms were mild and prognoses good, so the present results
cannot be extrapolated to the overall patient population with
NVAF. Because this was a retrospective study, it may have been
affected by recall bias and it was difficult to select reasonable
controls. Therefore, larger prospective studies would be needed
to verify the conclusions. Finally, although TEE has high
sensitivity and is the gold-standard test for LA/LAA clots,
it cannot discern thrombi less than 2 mm and therefore may
produce false negative findings.
Conclusions
This study suggests that LAAmorphology is a powerful predictor
of thrombus formation and possible subsequent arterial embolic
events in patients with NVAF. Compared with the CHADS2 and
CHA2DS2-VASc schemes, the L2CHADS 2 score developed here
has the advantage of identifying ‘truly low-risk’ patients without
sacrificing overall predictive ability. It can provide insights
into the value of the L2CHADS 2 score for the management of
patients with NVAF, which are novel and could prove to be
clinically very relevant. Of course, further prospective clinical
studies on the relationship of the L2CHADS2 score to outcomes
in larger populations of NVAF patients will be needed before its
widespread adoption in the world.
This work was supported by grants from 2018 Supporting Project of Medical
Guidance (Chinese and Western Medicine) of Science and Technology
Commission of Shanghai Municipality (18411966700).
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