Download 1 Metastatic myocardial abscess on the posterior wall of left ventricle

Metastatic myocardial abscess on the posterior wall of left ventricle: a case report
Javaid Iqbal, Iftikhar Ahmed, Wazir Baig
Corresponding author:
Javaid Iqbal (JI): Department of Cardiovascular Science, Queen’s Medical Research
Institute, University of Edinburgh, UK
[email protected]
Other Authors:
Iftikhar Ahmed (IA): Department of Medicine, Leeds General Infirmary, UK
[email protected]
Wazir Baig (WB): Department of Cardiology, Leeds General Infirmary, UK
[email protected]
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Abstract
Left ventricular free wall myocardial abscess is a rare and potentially fatal complication
of infective endocarditis. Ante-mortem diagnosis of myocardial abscess using
conventional imaging modalities is both difficult and unreliable. We report a case of
tricuspid valve endocarditis caused by staphylococcus aureus and resulting in a metastatic
abscess at the posterior wall of the left ventricle. We have also briefly discussed various
diagnostic modalities including cardiac MRI in the diagnostic work up of myocardial
abscess.
Introduction
Myocardial abscess (MA) is a suppurative infection of the myocardium, endocardium,
native or prosthetic valves, perivalvular structures, or the cardiac conduction system. It is
a serious and quite life-threatening disease, where early recognition and institution of
appropriate medical and surgical therapy is vital for patient survival. The overall
mortality rate associated with staphylococcus aureus endocarditis is 42%. If treated with
antibiotics only, the mortality rate is 75%. If treated with antibiotics and surgery, the
mortality rate falls to 25%. The presence of an intra-cardiac abscess increases the
mortality rate 13.7-fold. In the past, most cases of myocardial abscess were found during
autopsy; however, detection of myocardial abscess can now be achieved ante-mortem,
using non-invasive diagnostic modalities including transthoracic echocardiography
(TTE), trans oesophageal echocardiography (TOE), radionuclide scintigraphy, computed
tomography (CT) scan, and magnetic resonance imaging (MRI).
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Case presentation
A 28-year old intravenous drug user was admitted in a district general hospital with a two
weeks history of fever, malaise and myalgia. He had no past medical history of note. On
examination he was pyrexial but hemodynamically stable. His cardiovascular
examination revealed signs of tricuspid regurgitation. His respiratory, abdominal and
neurological examination was normal. Clinically, the diagnosis of infective endocarditis
was suspected. His three sets of blood cultures were drawn and empirical intravenous
antibiotic treatment commenced.
His blood tests showed elevated white blood cell count with predominant neutrophilia
and mild normochormic, normocytic anemia. His ECG revealed non-specific ST-changes
but no conduction abnormality. His Chest X-Ray was within normal limits. Transthoracic
echocardiography confirmed vegetations on tricuspid valve with severe tricuspid
regurgitation. Blood cultures grew staphylococcus aureus and vigorous antibiotic
treatment was continued appropriately. However, patient’s condition continued to
deteriorate with spiking fever and worsening symptoms of right heart failure. He was
referred to the regional cardiothoracic centre for evaluation of valve surgery in the view
of uncontrolled infection.
On arrival to The General Infirmary at Leeds, the patient was acutely unwell with
temperature of 38.5°, pulse 120/min, blood pressure 100/70 and respiratory rate 26/min.
He had signs of sever tricuspid regurgitation and right heart failure. His chest X-Ray
showed multiple cavitating lesions depicting metastaic pulmonary abscesses. There was
also evidence of splenic abscesses on his abdominal ultrasound scan. Repeat
Transthoracic echocardiography confirmed vegetations on tricuspid valve with severe
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tricuspid regurgitation but there was also a small cavity detected in the wall of the left
ventricle which was a new finding (Figure 1). TOE was planned but the patient could not
tolerate it. Immediate surgical opinion was sought but the cardiothoracic surgeons were
reluctant to operate with limited amount of information. Cardiac MRI was obtained,
which exhibited a 4.5cm diameter left ventricular posterior wall abscess contained by
only a 2mm thin layer of myocardium (Figure 2). The abscess was considered to be in a
location suitable for surgical treatment and urgent surgery was planned but,
unfortunately, patient had a cardiac arrest prior to surgery and could not be resuscitated.
Discussion
MA has been reported in about 20% of patients with IE [1]. They are usually adjacent to
area of valve infection and represent a direct extension of the infection [2]. Rarely,
embolization of septic material results in a metastatic myocardial abscesses remote from
the main focus as was the case here [3]. Ante-mortem diagnosis of MA remains a
challenge and a high index of clinical suspicion is required. TTE has a sensitivity of 23 %
and specificity of 98.6% in diagnosing MA [4]. If Ellis et al criteria are used, TTE can be
86% sensitive and 88% specific [5]. However posterior location of an abscess can still be
easily missed [6]. At present, TOE is considered the investigation of choice for MA but it
has only 87% sensitivity and 94.6% specificity [7] and in our case patient could not
tolerate it. Cardiac MRI is a non-invasive imaging modality with high temporal and
spatial resolution. To our knowledge, no studies have compared the diagnostic value of
TOE and cardiac MRI in such cases. However, our experience shows that in suitable
patients, cardiac MRI has superior diagnostic yield and provides better morphological
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evaluation to plan surgical intervention [8]. In the setting of prosthetic valves Indium-111
or Technetium-99 leukocyte scintigraphy can also be helpful to reveal a focal area of
increased uptake in the myocardium suggesting location of abscess [9]. The patients with
this lethal disease can be saved by aggressive antibiotic treatment and prompt surgical
intervention [10]. This can be best achieved by a multidisciplinary care involving
cardiologists, microbiologists, cardiac radiologists and cardiothoracic surgeons.
Conclusions
In conclusion, myocardial abscess is a life threatening illness. A high index of clinical
suspicion is required to make a prompt diagnosis. Final diagnosis may need multimodality imaging. An early diagnosis, aggressive medical therapy, multi-disciplinary
care and timely surgical intervention may save life in this otherwise fatal condition.
Consent
Written informed consent was obtained from the patient’s next of kin for publication of
this case report and the accompanying images. A copy of the written consent is available
for review by the Editor-in-Chief of this journal.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
JI collected data, performed the literature search and drafted the manuscript.
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IA was involved in the literature search and manuscript review.
WB supervised this patient’s care and the preparation of the manuscript.
All authors approved the final manuscript.
Acknowledgements
1. Professor Mohan Sivananthan, Leeds General Infirmary, for providing expert
opinion on MR images
2. Dr. Fizah Shafiq, University of Uxbridge, for proof reading the manuscript
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Figures:
Figure1: Transthoracic Echo - Short axis view showing abscess cavity
Figure 2: Cardiac MRI - 4.5cm diameter left ventricular posterior wall abscess contained
by only a 2mm thin layer of myocardium
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Figure 1
Figure 2