What Should We Do With an Anomalous Coronary Artery (ALCA) With a Malignant Left Main Course in an Asymptomatic Patient?

The incidental finding of a coronary anomaly is becoming more common with the use of computer tomographic coronary angiography (CTA). Management of such patients depends on symptoms, clinical setting, and our confidence in the prognosis associated with the patient’s specific anatomy. Among the many pathways that the anomalous left main (LM) coronary artery (ALMCA) can take, the most worrisome is the malignant intra-arterial course between the aorta and pulmonary artery, as previously discussed in these pages and elsewhere.¹ 

Dr. Paul Teirstein, Chief of Cardiology, at Scripps Clinic, La Jolla, California, asked our cath lab experts for their opinions on what to do with an asymptomatic executive who had a screening CTA (Figure 1). “The patient is very active and completely asymptomatic. A CT was done because he wanted to see if he had any coronary disease. All three coronary vessels come from the RCA [right coronary artery] with the LAD [left anterior descending coronary artery] traveling between great vessels, i.e., the high-risk path. My questions are: 1) Do we need to do more testing, i.e., stress test and perhaps cardiac monitor to look for VT [ventricular tachycardia]? 2) Should we go straight to CABG [coronary artery bypass graft surgery]?”

Mort Kern, Long Beach VA: Paul, a tough call, as always with this problem. The discovery of an asymptomatic, potentially life-threatening anatomy still requires some reason to operate on this middle-aged patient and unroof the LAD ostium with the potential complications thereof. I favor some demonstration of ischemia obtained during maximal exertion. We reported an investigation using fractional flow reserve (FFR) during dobutamine and adenosine in a 14-year-old patient with ALMCA from the right coronary cusp with vague symptoms and only a lateral perfusion defect.² In Paul’s patient, I favor a stress perfusion study (or the equivalent thereof). I would also strongly consider an invasive FFR, recognizing the difficulty of cath, etc. As an aside, had this patient not been so curious, he wouldn’t have put you (and himself) in this difficult situation. (Just saying, maybe he should have had a stress test first, then the CTA or cath, if positive).

Jeffrey Moses, Columbia University: Drop the LIMA; occlude the LM.    [MK: Thanks, Jeff; as always, to the point.] 

George Vetrovec, Medical College of Virginia: A difficult decision. Given his age, I would strongly consider surgery. If he were 75, I would get a stress test and if negative, assume he has made it this long and it’s likely not to be a clinical problem. But, at 51, yes, he has avoided a problem, but as he ages, his myocardium is likely to become stiffer, which might increase the significance of his anatomy. 

David Kandzari, Piedmont Hospital: USC has one of the most experienced surgeons in the U.S. for creating a baffle for this anomaly (CABG is NOT a solution). I sent two patients with VT/ventricular fibrillation (VF) to him when I was at Scripps. Interestingly, they were both women who became symptomatic in their late 40s, so very different than this patient.  

Will Suh, UCLA: Wow, interesting dilemma! The LAD ostium does not appear to be slit like on the CT. If he has made it to his sixth decade of life without sudden cardiac death, he should be fine without unroofing. I agree with Dr. Kandzari that CABG is the wrong surgery since LIMA won’t mature. I had a case last year with unroofing. The CT nicely shows the neo ostium after surgery (Figure 2). In contrast to Paul’s patient, my patient was symptomatic, the reason he was referred for surgery. My vote is beta blocker without surgery. Wouldn’t it be nice to have the device from “Men in Black” that erases people’s memory so that he doesn’t have to live with anxiety for the rest of his life? [MK: We wish…]  

Pinak Binip Shah, Brigham and Women’s Hospital: This may be one case where I would consider a coronary angiogram, even in the setting of reassuring non-invasive testing to determine: 1) the size of the LAD and how much myocardium subtended and 2) to consider intravascular (IVUS) of the LAD to look for a “slit” orifice. I’m not sure we can tell on these CT slices. Plus, a 2.5 mm LAD is likely small for this man, so it may be compromised. If angiography/IVUS is concerning, I would have the conversation about the unknowns [i.e., risk/benefits of surgery], but would have a low threshold to refer to surgical correction, not CABG.

John Hirshfeld, University of Pennsylvania Medical Center: I agree that a physiologic assessment should be the first step, although the validity of finding no compromise has been questioned. We should look at the rest of the arteriogram as well. Given that the proximal LAD is small, it is possible that it is just a small LAD with a small perfusion territory and a comparatively unimportant vessel. 

Stenting as Alternative to Surgery for the ALMCA?

Andrew Doorey, Christiana Hospital: I would agree with Mort that some demonstration of ischemia should be a basis for intervention. But remember, stenting is a reasonable alternative to surgery. We published a number of cases of anomalous coronaries causing ischemia (without atherosclerotic lesions) treated effectively with first-generation stents.³ We confirmed absence of ischemia on follow-up testing. As far as I know, and I follow many of these people personally, there has never been a subsequent ischemic complication. While most of our cases were anomalous right coronary arteries (RCAs) (with slit-like ostium), a sizable minority were ALCAs that passed between the major vessels. Technically, the cases are pretty easy. We struggled with getting the “inter-arterial” locale exactly, since we only had short stents then (we used intra-procedure transesophageal echocardiography [TEE] at times), but now with longer stents, it is much easier. 

Chris White, Ochsner Medical Center: Drew, have you considered looking at your patients in follow-up for the risk of stent crush? Many of us have been cautioned by the concern over external compression with coronary balloon-expandable stents, and this would be my primary concern in the anomalous LCA patients with risk of compression from the large vessels. 

Andrew Doorey, Christiana Hospital: Good point. We did do repeat angio on everyone at 6 months without any significant compression noted. We thought we had compression of an anomalous LCA, but this was at the ostium (aortic wall compression with the eccentric takeoff). It resolved after we used a third “generation” stent (generation here meant a new manufacturer came out with a stent). We tracked the radial strength of these stents carefully.³ There was no change in angiography at 6 months, resolution of ischemia, and no clinical events (although I only follow probably two-thirds of these patients clinically). We can’t exclude a longer-term risk, but we have used this approach routinely for this uncommon problem. It seems equivalent to surgery. 

Michael Lim, St. Louis University: Interesting problem. The real issue, for me, is finding an objective reason to go ahead with a surgical unroofing procedure rather than just going ahead with it based upon the anatomical pictures. Given that he is “asymptomatic”, I am doubtful that “true ischemia” on a non-invasive test or FFR will be shown. Dr. Paolo Angelini has nicely shown that dobutamine compression of the ostium of the left main with IVUS was a surrogate for [ischemia] correcting this anatomy. Our paper² demonstrated a gradient with an FFR with adenosine or dobutamine that wasn’t <0.80, but we were fine with the concept that a gradient, even though the FFR was only 0.85, was “abnormal” and recommended surgery. Thus, the key point, if you do more testing, is to define what you will be calling “abnormal” beforehand, because [most stress] tests that have been validated in obstructive, atherosclerotic disease may not readily translate to this scenario.

Jeannie Yu, VA Long Beach: As noted earlier, the featured coronary anomaly is one of the more malignant variants. It appears the take-off is quite acute (<45 degrees), and it would not be surprising if the orifice was at least oval (vs slit-like) on double oblique en face view and has at least some intramural course. The narrowing of the LAD may suggest >5.4 mm length of involvement, which is also associated with revascularization. Some suggest that IVUS may be superior to even CCTA in determining intramural course. One thing not mentioned is whether or not the course is subpulmonic versus truly inter-arterial (above the level of the pulmonic valve), the latter of which is associated with higher mortality.  According to a U.S. Army study, this is the anomaly that is most associated with sudden death. Furthermore, 50% of autopsy findings for sudden cardiac death in the setting of anomalous coronaries were in patients that had no preceding symptoms. Mike Cheezum and Brian Ghoshajra mentioned in their 2017 paper in EHJ⁴ the absence of symptoms or ischemia is not necessarily protective or predictive of sudden cardiac death (SCD). Given the type of coronary anomaly he has, I would think it reasonable to aggressively pursue ischemic testing with max exertion on treadmill for electrocardiogram (EKG) and perfusion changes, as well as left heart cath with IVUS and FFR if the anatomy permits (the acuity of the take-off may be a technical issue).

Kirk Garratt, Christiana Hospital: It is worth emphasizing that FFR using adenosine will not be a sensitive method for risk assessment. Dobutamine stress testing will increase contractility and drop afterload, and so would be the better method of assessing a dynamic lesion’s significance, but it doesn’t mimic exercise physiology perfectly. I’m with Mort: maximal exercise stress testing is needed. Combining dobutamine with exercise in the lab (using a leg ergometer) during FFR might also be helpful, but I worry about an unknown impact of the wire crossing over the ostium.

Paul Teirstein, Scripps Clinic: From several stent manufacturers, I am told that all of the current stents get tested in a “vice”-like device that measures radial strength and also in a 2-plate device that tests lateral strength. They all collapse at between 1000 mmHg and 12000 mmHg. Given that the systole is rarely >200 mmHg, it seems unlikely that a stent would ever get crushed. So I suspect stenting is the best approach when treatment is needed. 

The Bottom Line

I thank all our contributors for adding their thoughts and helpful comments. Dr. Teirstein reported that a full review of the CTA and a maximal exercise treadmill with nuclear perfusion with an invasive cath study with IVUS and FFR will follow. Stenting may be better than surgery with unroofing of the intramural LM ostium. CABG is not a good option. We should remember that it takes experience and collaborative knowledge-sharing to make the best decisions for the most complex and uncommon potentially life-threatening scenarios.

References

1. Kern MJ. Anomalous coronary artery angiography made simple. Cath Lab Digest. 2013 Dec; 21(12): 4-8. Available online at https://www.cathlabdigest.com/articles/Anomalous-Coronary-Artery-Angiography-Made-Simple. Accessed April 11, 2018.
2. Lim MJ, Forsberg M, Kern MJ. Images in cardiovascular medicine. Provocable pressure gradient across an anomalous left main coronary artery: a unique diagnostic tool. Circulation. 2005 Mar; 111: e108-e109.
3. Doorey AJ, Pasquale MJ, Lally JF, et al. Six-month success of intracoronary stenting for anomalous coronary arteries associated with myocardial ischemia. Am J Cardiology. 2000; 86: 580.
4. Cheezum MK, Ghoshhajra B, Bittencourt MS, et al. Anomalous origin of the coronary artery arising from the opposite sinus: prevalence and outcomes in patients undergoing coronary CTA. Eur Heart J Cardiovasc Imaging. 2017 Feb; 18(2): 224-235.

Further Reading in CLD

1. Kern M. Anomalous coronary artery angiography made simple. Cath Lab Digest. 2013 Dec; 21(2). Available online at https://www.cathlabdigest.com/articles/Anomalous-Coronary-Artery-Angiography-Made-Simple. Accessed April 13, 2018.
2. Vasilevskiy L, Akhondi H, Robine D. Anomalous left main coronary artery in a STEMI patient. Cath Lab Digest. Apr 2018; 26(4): 42-44. Available online at https://www.cathlabdigest.com/article/Anomalous-Left-Main-Coronary-Artery-STEMI-Patient. Accessed April 13, 2018.

Disclosure: Dr. Kern is a consultant for Abiomed, Merit Medical, Abbott Vascular, Philips Volcano, ACIST Medical, Opsens Inc., and Heartflow Inc.