Case presentation
A 78-year old gentleman with wild type CA was referred for consideration
of CABG. During an amyloid clinic walk test he suffered a cardiac arrest
secondary to ventricular fibrillation. Spontaneous circulation returned
after a single direct current electrical cardioversion. Myocardial
ischaemia was thought to be causative and coronary angiography revealed
triple-vessel coronary artery disease with left main stem involvement
(Fig 1). Cardiac magnetic resonance imaging (Fig 2) was characteristic
of CA, with severe biventricular hypertrophy, mildly reduced left
ventricular ejection fraction (LVEF) of 58%, and severely reduced
longitudinal function of both ventricles. On tissue characterisation
transmural late gadolinium enhancement was present with biventricular
involvement.
Other medical history included percutaneous intervention (PCI) to the
left anterior descending artery (LAD) 2 years previously and paroxysmal
atrial fibrillation. The patient’s baseline functional classification
was New York Heart Association II.
The case was discussed in the coronary intervention multi-disciplinary
team meeting. Input from amyloid specialists suggested that if the
patient were not to have coronary artery disease, prognosis for CA would
be 60-84 months. Euroscore II suggested a 2.32% mortality risk, but due
to the severity of CA this was felt to be a considerable underestimate.
Given complex coronary anatomy and left main stem involvement, albeit in
the presence of CA, consensus decision was for high risk inpatient CABG.
Considering good LVEF of 58% and excellent functional baseline, a
balanced mortality risk of 5-8% was quoted.
Surgery took place two weeks later. The heart was extremely hypertrophic
and beefy, and cardiac manipulation was impossible. Peri-operative TOE
revealed severe biventricular hypertrophy with preserved systolic
function. Three bypass grafts were undertaken: saphenous vein conduits
to the posterior descending artery and first obtuse marginal, and
pedicled left internal mammary artery to the LAD. The patient came off
cardiopulmonary bypass easily on low dose milrinone. In view of severe
LV hypertrophy, an intra-aortic balloon pump was placed via the right
femoral artery.
Over the next 24 hours the patient became increasingly hypotensive and
vasoplegic. Worsening metabolic acidosis ensued despite fluid
resuscitation and increasing vasopressor and inotropic support with
noradrenaline, vasopressin and milrinone. A Swan-Ganz catheter was
inserted, and cardiac index calculated at 1.8L/min/m2 with low systemic
vascular resistance. TOE showed a small pericardial collection. Given
continued deterioration, the patient returned to theatre for
re-sternotomy to exclude tamponade. All conduits were patent, and whilst
some clot was evacuated from the pericardium there was no consequent
change in haemodynamics. The chest was closed, and the patient returned
to ICU with an adrenaline infusion added.
Over the following days the clinical condition slowly improved.
Inotropic and vasopressor requirements decreased, and the balloon pump
was removed 3 days postoperatively allowing tracheal extubation. As a
result of prolonged LCOS, liver and renal failure ensued. The patient
developed marked jaundice and required continuous renal replacement
therapy. Haemodynamics continued to stabilise over the subsequent 2
weeks allowing weaning of inotropic support. Despite this, there was no
resolution of organ failure and he remained jaundiced and filter
dependent. Three weeks following surgery the patient again deteriorated
with a profound LCOS, requiring increasing doses of noradrenaline,
milrinone and adrenaline. Echocardiogram showed severe biventricular
impairment with low stroke volume and high filling pressures, but no
evidence of tamponade. In the context of CA and multi-organ failure,
consensus opinion was that further intubation, ventilation, and organ
support would be futile. Following family discussions, a do not
resuscitate order was completed and decision for no further escalation
in treatment agreed. The patient died shortly thereafter.