Refractory Angina and Anterior Ischemia in a Patient with a Patent Left Internal Mammary Artery Bypass Graft

Case Description.A 50-year-old man was referred to our institution for evaluation and management of angina pectoris. He had experienced exertional chest pain three years prior to this admission, which had initially been treated medically. However, accelerating symptoms prompted risk stratification and subsequently coronary artery bypass graft surgery within one year of diagnosis of coronary artery disease. He received a left internal mammary artery (LIMA) graft to the left anterior descending artery (LAD) and sequential saphenous vein graft (SVG) to the first and second obtuse marginal branches. Following surgical revascularization, he was initially able to return to an active lifestyle without symptoms. He subsequently presented with recurrent angina pectoris. Exercise TC-99m Sestamibi stress testing demonstrated a medium size area of reversible ischemia of the anterior wall. Coronary angiography revealed an 80% stenosis of LAD distal to the anastomosis of the LIMA graft. This was successfully dilated and stented, but resulted in only partial relief of symptoms. He was then referred to our institution for a second opinion. His past medical history was significant for hypertension and hyperlipidemia. Current medications included aspirin, a beta-blocker, an angiotensin-converting enzyme (ACE) inhibitor and a nicotinic acid derivative. Physical examination was remarkable for a temperature of 37.6° C, a regular heart rate of 76 beats per minute, blood pressure of 156/92 mmHg, respiratory rate of 14 breaths per minute, height of 177 cm, weight of 79 kg, and a body mass index of 25 kg/m2. The neck veins were not distended and no carotid bruits were detected. The heart sounds were normal and there were no obvious murmurs, rubs of gallops. Abdominal and neurological examination was normal. The peripheral pulses were normal and there was no pitting edema. Diagnostic coronary angiography revealed total occlusion of the LAD at the origin of the first diagonal branch. The left circumflex artery was of small caliber and diffusely diseased. There was mild, non-obstructive disease of the right coronary artery. The sequential SVG was widely patent. The LIMA was widely patent and the distal LAD had mild non-obstructive disease, without evidence of in-stent restenosis. However, there was critical narrowing of the ostium of the second diagonal branch, which was visualized by retrograde filling of the LAD by the LIMA graft. *endicsubendsub** Howard C. Herrmann, MD University of Pennsylvania Medical Center Interventional Cardiology Philadelphia, Pennsylvania This case presents no easy interventional option. There is no mention of a subsequent stress test confirming the second diagonal artery as the source of the patient’s angina. However, assuming this to be the cause, I would start with more aggressive medical management. The patient’s reported blood pressure (156/92 mmHg) and heart rate (76 beats/minute) suggest "room" for additional beta-blockade and anti-hypertensive therapy. A long-acting nitrate medication might also be helpful. If the patient remained symptomatic on an intensified regimen with provocable ischemia in the diagonal territory, then the interventional approach undertaken provides an elegant solution to his problem. However, the technical challenges and lower success rate crossing a chronic total occlusion, the risk of jeopardy to a large septal perforator branch, the need for multiple stents, and the increased risk of restenosis, would make this a second choice therapy for me. James Ferguson, MD St. Luke’s Episcopal Hospital Texas Heart Institute Houston, Texas In reviewing this case (and this may be a little heretical in an interventional cardiology journal), I would have opted for medical management. The patient has undergone bypass surgery with a patent LIMA to the LAD, but is incompletely revascularized. He has a high-risk diagonal lesion at the ostium of the second diagonal, which was approached via a totally occluded LAD. The problem with pursuing an interventional strategy in this gentleman is that I’m not sure the risk benefit ratio is anywhere close to favorable. Given the presence of adequate (though incomplete) revascularization and stable coronary lesions, I believe that by intervening, you: • Potentially jeopardize the LAD; • Potentially jeopardize a perfectly good LIMA; • Have an exceedingly high risk of restenosis (total occlusion, ostial lesion) in both the LAD and the diagonal; and • May take an otherwise stable, non-acute atherosclerotic process and convert it to a potentially unstable one (with a high risk of subsequent closure, potentially acute). The patient’s blood pressure is inadequately controlled. His anti-anginal management can be improved upon a lot. We have no documentation of high-risk features in his stress test, other than demonstrable ischemia on perfusion scanning. He is not on a statin. The status of other potentially modifiable risk factors is unknown. Simply stated, I feel the risk of doing a percutaneous revascularization procedure in this patient is not really justified at this point. Yes, he has symptomatic angina, but it is stable. The expected long-term patency of this lesion following revascularization is dismal, and when he comes back with restenosis (hopefully rather than a new acute event), you will be exactly where you started out (if you are lucky), or potentially with even less favorable or stable anatomy (if you are not). I don’t think you have done the patient any favors, and you have risked destabilizing an otherwise stable situation. James Tcheng, MD Duke University Medical Center Durham, North Carolina This case featured a number of decision points where each step depended on the previous step and contributed to the success of the next. From an overall management standpoint, the operators are to be commended for a logical, sequential approach to the difficult anatomic dilemma of the isolated large diagonal branch not ordinarily approachable by conventional means. The first decision point presented itself even before the referral for PCI. In my mind, there were 4 other alternatives that needed to be considered: continued medical therapy, PCI of the diagonal via the LIMA, redo CABG, or TMR. However, these can be quickly discarded: the patient had already proven refractory to medical therapy, the lesion was anatomically impossible to reach via the LIMA, re-do CABG would be difficult to justify given the small vessel diameter and lack of a mortality benefit, and TMR was unlikely to provide long-lasting relief. The second decision concerns the preparation for the PCI procedure. The key point to approaching chronic total occlusions is visualization of the vessel distal to the occlusion; the technique of simultaneous visualization via separate cannulation of two different coronary supplies frequently proves invaluable. Technically, vascular access using both the right and left femoral vessels is usually the most convenient, with a small (5 French) diagnostic catheter placed in the opposite groin cannulating the vessel providing the collaterals. Two complete manifold setups (with pressure transducer, flush bag, and contrast source) are recommended when using this technique. The third decision is the selection of the equipment to use to attempt the crossing of the total occlusion. My preference is to use a guide catheter formed to provide support from the back wall of the aorta (rather than a Judkins curve guide catheter). Support from the guidewire delivery catheter can also be invaluable; my choice is to use a single lumen catheter with a radioopaque tip marker (rather than a balloon catheter) since this will give better visualization of the exact position of the tip and reduce the potential for catheter tip-induced trauma. Guidewire choice is also critical; I would use a coated, hydrophilic guidewire rather than a conventional coil-tip wire. The timing of administration of a GP IIb/IIIa inhibitor should be mentioned. In our lab, we typically withhold therapy until after the lesion has been successfully crossed, the guidewire is identified to be in the true lumen, and distal vessel perforation has been confirmed to be absent. The last part of the puzzle still awaits further technological refinement. Unfortunately, PCI of total occlusions is still fraught with high rates of restenosis and reocclusion. Perhaps the anti-proliferative stents will finally solve this dilemma and render these cases truly and completely rewarding. George Vetrovec, MD Chairman, Division of Cardiology West Hospital Richmond, Virginia The attached illustrates important clinical and technical points. From a clinical perspective, this patient demonstrates that functionally important ischemia can occur in the face of patent grafts, particularly in the proximal left anterior descending (LAD) distribution when there is mid vessel occlusion precluding retrograde filling of the proximal vessel segment and the proximal vessel or left main has significant obstructive disease. The circumstances for ischemia are magnified when there are important diagonals at ischemic jeopardy, as in this example. Though not illustrated by this case, another scenario is one with similar anatomy as described, but important collateral filling of other ungrafted vessel(s) via septal collaterals, again producing symptomatic ischemia in the face of apparently satisfactory patent grafts. Thus, it is always important to assess the adequacy of revascularization by myocardial territory, not simply by graft patency; this information should be utilized in planning treatment. As to the technical approach to this procedure, I would concur with the antegrade approach to re-opening the LAD. From the illustration, attempting to approach the diagonal retrograde via the left internal mammary graft (LIMA) would have been much less ideal if possible at all. The sharp angulation would have made wire manipulation and balloon delivery difficult and stent delivery potentially impossible. In addition, there would also be the possibly of damaging the LIMA, thus compromising the stable distal graft supply. However, I am a "minimalist" and would not have accessed the LIMA from an alternative site unless I was having difficulty crossing the LAD antegrade. The safety of a case like this is the fact that even if the proximal lesion is in the left main, the majority of the distal vascular is "protected" by the grafts. Another ideal technical aspect of this case is the fact that the diagonal could be approached directly and stented across the LAD because of the distal graft. This is more ideal in terms of the quality of revscularization and long-term outcome compared to stenting across the diagonal and dilating through the stent, which may have been necessary in a circumstance without a distal graft. The latter approach often does not yield an optimal result in the diagonal. However, in this case the operators achieved an excellent angiographic result, which should provide an optimal opportunity for long-term patency. I certainly support the authors’ wire technique. Often in a chronic total, a stiffer wire is needed to cross the lesion and the use of an over-the-wire system not only gives better support for "pushability", but enhanced steerability of the guidewire, which may be important given the necessary rotation into the diagonal branch at or near the point of crossing the total occlusion. Lastly, I certainly concur with the use of a GP IIb/IIIa inhibitor, as this should provide the best outcome result for a complex procedure. Though not mentioned by the authors as part of the post-procedure medications, I must presume the patient was also discharged on lipid therapy, quite possibly a statin titrated to achieve an LDL cholesterol of