DISCUSSION
Spontaneous left atrial intramural dissecting hematoma is exceedingly
rare entity with unknown true incidence. Most of the information is
available from isolated case reports. From aetiological perspective LAIH
causes could be grouped into 4 major categories based on available
published literature. Firstly, it can be secondary to complications of
post cardiac surgeries like mitral and aortic valve replacement.
Secondly it can be a result of iatrogenic complications secondary to
percutaneous interventions (mainly due to high-risk coronary
interventions, and during radiofrequency Cath ablation in
electrophysiology lab [2-5]. Thirdly it has been reported
to occur in conditions like amyloidosis, mitral annular calcification
and/or annular abscess, blunt chest trauma and dissecting aortic
aneurysms and lastly as in our case it can be spontaneous[6-9]. Usually LAIH has predilection to posterior LA wall
(81%) due to lower quantity of fibrous tissue; however, in our case it
occupied the whole of left atrium. Our patient posed a diagnostic
dilemma as he did not have any predisposing factors and closely mimicked
acute coronary syndrome (ACS)/pericarditis at presentation which
mandated coronary angiogram. Retrospectively we thought that PR segment
depression on presentation EKG could be secondary to atrial ischemia
rather than ACS/pericarditis though there was no PR segment elevation.
The pathological report did show necrosis of underlying LA endocardium.
We used unfractionated heparin for ACS treatment initially which could
be hypothesized to cause cystic degeneration of LA intramural thrombus.
There is a close overlap between left atrial dissection and LAIH. The
former is thought to originate from contained atrioventricular
separation allowing pressurised blood flow from left ventricle to
dissect the layers of posterior LA. In our case surgeons observed
separation of endocardium and epicardium in posterior LA wall,
henceforth it might be appropriate to term this LA mass as spontaneous
intramural multiseptated dissecting hematoma. There are no definitive
guidelines for management with some cases having predisposing factors
being observed conservatively and majority of the cases went to
operating theatre, as they were symptomatic. The work up of LAIH starts
from imaging as clinical and laboratory parameters are mostly variable
and misleading.