Cardiovascular Journal of Africa: Vol 26 No 3 (May/June 2015)

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CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015 AFRICA 123
patients with atrial myxoma.23 Large myxomas may almost fully
occupy the atrial outflow and lead to increased LA pressure.24 As
a result, obstructing atrial outflow and atrial arrhythmias could
contribute to elevated LA pressure and dilated LA cavity.
Atrial overload or ventricular hypertrophy, which secondarily
increased the chamber diameter and altered conduction, could
lead to abnormal electrocardiography findings.25 Also tumour size
may have been responsible for the changes on ECG.26 Harikrishnan
et al.21 showed that larger tumour size correlated with LA
enlargement on ECG in patients with LA myxoma. They also
showed that evidence of LA enlargement on ECG disappeared in
most patients after excision of the tumour. However, Aggarwal et
al.27 found no correlation between tumour size and signs of LA
enlargement on ECG. They found that only 35% of the patients
with myxoma had signs of LA enlargement on ECG.
In our study, we found that neither tumour volume nor
LA dimensions correlated with postoperative AF. However,
pre-operative Pd and age were independent predictors of
postoperative AF in our cohort. We also found that P-wave
duration, amplitude and Pd were significantly shortened after
tumour resection.
Abnormal P-wave morphology reflects abnormality of
LA size and LA structural abnormalities.13 Previous reports8,28
showed that age and LA dimension are independent predictors
for occurrence of AF after cardiac surgery. However, a prior
study has demonstrated that age and LA dimension were not as
powerful as abnormal P-wave morphology.13
Similar to previous studies, 8,13,28 our results suggested that
abnormal P-wave morphology was the main independent
predictor for the development of postoperative AF but the
aetiology of AF following cardiac surgery was multifactorial.
Pre-operative factors such as age, previous rheumatic fever,
hypertension, coronary syndromes, LV hypertrophy, LA
enlargement, history of congestive heart failure, electrolytic
imbalance, obesity, male gender, chronic obstructive pulmonary
disease,29 and surgical factors such as traumatic laceration of
the atrial tissue (suture line, haematoma and other traumatic
causes)30 may increase the incidence of postoperative AF.
LV diastolic dysfunction led to an increase in LV end-diastolic
diameter and LA pressure. The elevated atrial pressure dilates the
atrium and triggers non-homogeneous fibrosis, which changes
the shape and geometry of the atrium. All these changes may
induce atrial arrhythmias, especially atrial fibrillation.31,32 P-wave
dispersion was also demonstrated to be influenced by elevated
LA pressure.33
In our study, LV diastolic function was impaired in patients
with postoperative AF. Although statistically non-significant,
tumour volumes of postoperative AF patients were higher,
suggesting a positive effect on atrial pressure. Higher atrial
pressure may prolong the duration and dispersion of the P wave
in this patient group. There was no difference between patient
groups in terms of LA dimensions, which may have been a result
of inaccurate measurement. LA volume or multiplane dimension
measurements could clarify our results.
Maximal P-wave duration and Pd have been shown to
be a non-invasive predictor of AF in patients with mitral
and aortic stenosis, dilated cardiomyopathy, acute myocardial
infarction, and atherosclerotic heart disease.34,35 However, there
has been no study evaluating the predictive value of Pd for
postoperative AF in patients with LA myxoma. Our study
suggests a significant association between postoperative AF
and pre-operative Pd values in these patients. All patients who
developed AF postoperatively had significantly increased Pd
(more than 40 ms).
We also found that patients who developed postoperative
AF were significantly older than non-AF patients. Previous
reports estimated a 24% increase in the incidence of new-onset
postoperative AF with each additional five years of age. 36
Age-related degenerative change and electrophysiological
abnormality of atrial cells are the main causes of post-CABG
AF in advanced age, mainly patients older than 70 years of age.37,38
Cardiac myxomas are the most common primary tumour
of the heart, and roughly 90% of the tumours are located
in the atria, with the LA accounting for 80% of those.25 The
most common symptom is dyspnoea, followed by palpitation. 39
Atrioventricular valve and outflow tract obstruction, and AF
may contribute to dyspnoea and palpitation. Dyspnoea was the
most common reported symptom in our study.
Symptoms depend on the size, form, mobility and location
of the tumour.40 The obstruction, mainly caused by large,
pedunculated tumours, can decrease cerebral flow and lead to
syncope. Also the risk of embolism is higher for polypoid or
multilobular tumours.41 Twelve patients presented with cerebral
symptoms in our study and their tumours were larger than those
without cerebral symptoms.
Study limitations
The retrospective design of our study and the small sample
size were limitations. Third, there was no long-term Holter
monitoring for the detection of AF episodes. Continuous-
rhythm Holter monitoring during the intensive care period, and
telemetry monitoring up to discharge may be a more accurate
method to detect transient episodes of AF during hospital stay.
Fourth, tumour volume was calculated with the assumption that
the tumour was spherical in shape.
Conclusion
This study showed a high incidence of postoperative AF
following surgery in patients with LA myxoma. To identify
patients at risk for AF after surgery, Pd is an independent
predictor and can be used for patient risk stratification.
References
1. Mahoney EM, Thompson TD, Veledar E, Williams J, Weintraub WS.
Cost-effectiveness of targeting patients undergoing cardiac surgery for
therapy with intravenous amiodarone to prevent atrial fibrillation. J Am
Coll Cardiol 2002; 21; 40: 737–745.
2. Attaran S, Shaw M, Bond L, Pullan MD, Fabri BM. Atrial fibrillation
postcardiac surgery: a common but a morbid complication. Interact
Cardiovasc Thorac Surg 2011; 12: 772–777.
3. Hata M, Akiyama K, Wakui S, Takasaka A, Sezai A, Shiono M. Does
warfarin help prevent ischemic stroke in patients presenting with post
coronary bypass paroxysmal atrial fibrillation? Ann Thorac Cardiovasc
Surg Aug 2012; 20. [Epub ahead of print].
4. Treggiari-Venzi MM, Waeber JL, Perneger TV, Suter PM, Adamec R,
Romand JA. Intravenous amiodarone or magnesium sulphate is not cost-
beneficial prophylaxis for atrial fibrillation after coronary artery bypass