Anomalous coursing LCA: always go into the valley of death?

December 1, 2016 Posted by Dr. Duncan Hogg no Comment

“Which way round do you think it goes, anterior or posterior to the aorta?”, said the interventional fellow. My staff replied: “Well, you could do more views whilst I consult the textbook…then you could do more views with a PA catheter in-situ…then take a few more views….but really you need to stop, and request a CTCA!”

Cardiac CT is of such great benefit for these patients (and us), taking away almost all diagnostic doubts in anomalous coursing coronaries. But, looking after your patient after this remains difficult. Much is well described but due to their rarity there is only a modest evidence-base behind further interventions.

Recently I was prompted to revisit Anomalous Coronary Artery from the Opposite Sinus (ACAOS) with the left main arising from the right sinus, and coursing between the aorta and pulmonary, the so-called “malignant course”. I asked our MDT: “What is the best action for a middle-aged asymptomatic patient with ACAOS left main from right, is it always cardiac surgery?

My n=1 before this was an early 50s man who presented with an initially typical inferior ACS, with an inferior WMA on echo, and angio, showing some moderate diffuse atheroma in the distal RCA, which was not subject to PCI. He had a normal ETT, and a holter showing no NSVT. His case was discussed in MDT, and it was agreed in the short-term to follow-up without the offer of surgery. When he was followed in clinic he had complaints of limb tingling and discomfort, lethargy, but no chest pain. Over a year later he was admitted under a colleague with cTnI –ve chest pain, and had in-patient cardiac surgery with two SVGs to his left coronary artery (LCA). He came back to out-patients about 5 months later having just been diagnosed with Huntington’s and unfortunately died of this no more than a year later.

We weren’t going to make him feel better, but did we save him from a sudden cardiac death (SCD) with our intervention? Probably not.

My current patient is over 45 years and completely asymptomatic, seen initially for the incidental finding of LBBB, with normal echo & CMR; DSE was normal; normal BP response to 15 minutes on ETT; normal holter. I recommended avoiding the most strenuous or explosive of exercises, and follow-up with further ETTs and holters. Fascinatingly, there is an identical twin, who was investigated similarly for LBBB, but without the ACAOS finding!

The data is clear that ACAOS left from right, is found disproportionately highly at post mortem in SCD of athletes and army recruits. The mechanism of myocardial ischemia and ventricular arrhythmia due to LCA compression in a hyperdynamic setting fits well enough in these groups.

But, in older individuals when you are naturally less active and your aorta and pulmonary artery have reduced elasticity, is this still going to be the problem? Is the path between the aorta and the PA still “the valley of death”, as you get into middle-age?

The compressive mechanism alone is probably not the only one leading to SCD. The anatomical nature of the orifice may be an influence, as might abnormal vasomotor function, with spasm being the mechanism causing  ischaemia and ventricular arrhythmias.

Cardiac surgery for ACAOS left from right may be a one-off for our patient but it will still have lasting implications, and will it really save their life?

And, assuming it does, what is the best form of surgery? Without a fixed obstruction, arterial grafts aren’t going to take; vein grafts in your 50s aren’t likely to last you a lifetime; coronary re-implantation in the right hands is probably the best option, but that may not be in the armamentarium of your local surgeon, or in fact very many.

Current guidance is based on small series with modest follow-up and expert opinion; but it is recommended that this is always offered for ACAOS left from right.

So, next time you are in the lab with those anomalous coronaries and your registrar or fellow gets excited in identifying the anatomy, remember to share that the harder work is still to come with the clinical decision-making. And maybe, you don’t need to charge into changing what is in the valley of death in all ACAOS?

 

 

This Blog is Posted by Dr. Duncan Hogg

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