CLINICAL DECISION MAKING

Post-Stent Very Proximal Left Anterior Descending Coronary Artery Aneurysm

David Lubell, MD and Luis Gruberg, MD
David Lubell, MD and Luis Gruberg, MD
Case description. A 39-year-old male with recent onset angina was admitted to our department with an acute infero-lateral myocardial infarction. The patient had no prior cardiac medical history, except for episodes of chest pain in recent months. As a result of the chest pain, the patient performed a cardiac stress test, which was positive for ischemia. He did not have other cardiac risk factors and did not undergo further evaluation. Due to severe and prolonged chest pain on the day of admission, he presented to the emergency room where the electrocardiogram revealed Q-waves and S-T segment elevation in all three inferior leads with a first degree A-V block. The patient was treated with thrombolytic therapy (STK) with signs of successful reperfusion, after which the patient remained asymptomatic. Laboratory studies showed a peak cardiac troponin-I of > 50 ng/ml and a creatine phosphokinase (CK) of 2,072 U/L with elevated homocysteine levels and reduced HDL levels. An echocardiogram performed two days after admission revealed mildly reduced left ventricular systolic function, segmental wall motion abnormalities and right ventricular dysfunction. In addition to the inferolateral infarct, the echocardiogram demonstrated a posterior and right ventricular infarct. Eight days after admission the patient underwent coronary angiography that revealed two-vessel disease involving a severe stenosis in the mid-portion of the left anterior descending coronary artery (LAD) and of the distal right coronary artery (RCA) (Figure 1 A and B). There was also a 50–75% lesion in the ostial portion of the posterolateral artery. Primary stenting of both the mid-LAD and the distal RCA were successfully performed and plain balloon angioplasty of the ostial portion of the posterolateral artery (Figure 1B and 2B). There were no peri-procedural complications and the patient was discharged the next day on dual antiplatelet therapy (aspirin and clopidogrel), statins, beta-blockers and ACE inhibitors. Two months later the patient performed a routine stress test, which was positive for ischemia. Ten days after the exam, the patient experienced recurrent episodes of chest pain, shortness of breath and cold sweats. The symptomatic episodes became more frequent and three days later, the patient admitted himself to the hospital emergency room. An electrocardiogram on admission did not show any significant changes and cardiac enzymes were normal. Coronary angiography at this time revealed that all previous stents remained patent, but a pseudo-aneurysm had developed in the proximal portion of the LAD (Figure 3A) that compromised the proximal portion of the stent and the origin of the first diagonal branch (Figure 3B). Furthermore, there was a 90% lesion in the mid-RCA, proximal to the stent previously deployed (Figure 3C). Considering the perilous position of the pseudo-aneurysm and the unstable status of the patient, a debate ensued as to what type of intervention could be performed safely and with optimal long-term results. James B. Hermiller, Jr., MD, FACC Director, Cardiac Catheterization Laboratory The Care Group at St. Vincent’s Hospital Indianapolis, Indiana This patient’s unstable syndrome is likely due to the high-grade stenosis in the right coronary artery just proximal to the previous stent. There had been a modest stenosis in this area at the time of the original PCI with subsequent disease progression. This lesion could be easily direct-stented with a drug-eluting stent. Intravascular ultrasound interrogation pre- and post-stenting would be helpful, ensuring optimal stent expansion and lesion coverage. The LAD lesion is more problematic, because the aneurysmal segment is adjacent to a moderate-sized diagonal branch. Coronary aneurysms are noted in 0.3 to 4.9% of diagnostic coronary angiograms. Aneurysms following coronary intervention are uncommon and are more likely to occur following ablative techniques, particularly excisional atherectomy with or without stenting. Although there was initial concern that the sirolimus or paclitaxel-eluting stents might cause aneurysm formation, randomized studies have shown no greater risk compared to bare metal stents. In the TAXUS IV study, only 1 of 558 patients having angiographic follow-up developed an aneurysm and this occurred in a patient receiving a bare metal stent. Potential complications of coronary aneurysms include thrombosis, distal embolization, rupture, vasospasm and myocardial infarction. The natural history and prognosis remains obscure. Assuming that this aneurismal segment requires intervention, IVUS would be essential in planning a therapeutic strategy. The size and location of the aneurysm in relation to the diagonal branch and presence of obstructive LAD disease could be precisely determined using IVUS. One could also verify whether this was a pseudoaneurysm (PSA) as the three-layered appearance typical of coronary arteries would be absent in a PSA. There are several approaches to this lesion. In narrowed neck aneurysms due to plaque ulceration, simply stenting over the origin of the dilated segment will often compress the entrance to the dilated segment, resulting in closure of the aneurysmal area at follow-up. Of course, a PTFE-covered stent could be employed to seal off the PSA; however, the side branch would be sacrificed. A more favorable approach was recently presented by Ioannis and Colombo.1 They recently describe the use of a custom-modifed PTFE-covered stent. An appropriately sized JoStent is inflated, and with a surgical blade, an opening is made in the middle of the stent the size of one cell, creating a side branch opening. A 1.5 mm balloon is inserted through the opening and sandwiched with a deployment balloon. The system is then advanced over the diagonal and LAD wires and each balloon is inflated separately and then together. A second stent is then telescoped through the side of the JoStent and deployed in a T-stent geometry. High-pressure deployment (20 atm) would be employed and IVUS would be utilized to ensure complete stent expansion. Reference 1. Iakovou I, Stankovic G, Montorfano M, et al. Is overdilatation of 3.0 mm sirolimus-eluting stent associated with a higher restenosis rate? Cathet Cardiovasc Intervent 2005;64:129–133. Peter Gonschior, MD Medizinische Klinik Wallgau, Germany A 39–year–old patient with significant signs of myocardial ischemia received thrombolysis and was later adequately treated interventionally with conventional stenting after a substantial myocardial infarction. Only two months later, the follow-up reveals an aggressive form of coronary artery disease with an aneurysm at the proximal LAD stent involving the first diagonal branch and a stenosis proximal to the RCA stent. It is not clear why a patient at that age with signs of myocardial ischemia did not undergo an immediate angiogram and adequate treatment, with the result being an unnecessary, substantial infarct. If the patient’s compliance is the problem, strict follow-up schedules should be planned. It should be possible to explain to a 39-year-old patient the consequences of undergoing early bypass surgery. Furthermore, regular noninvasive work-ups of the patient’s peripheral arteries should be performed to avoid further unnecessary ischemia. Intravascular ultrasound (IVUS) has recently revealed further insight into coronary pathology, especially in cases with coronary events and no angiographic signs of stenosis. In this case, a prior IVUS at the site of the aneurysm should be able to specify the anatomy (site of aneurysm, mechanism of aneurysm formation and perfusion, length, etc.) and enable the physician to work out the strategy to cover the origin of the arterial malformation safely with interventional means and to avoid surgery for such a young patient. Stenting with conventional devices should be better able to close the aneurysm and provide a sufficient long-term outcome. A prerequisite is that no signs of cellular necrosis at the aneurysm site are found and that malapposition of the stent should be avoided. If balloon dilatation after IVUS with occlusion of the side branch shows signs of ischemia, the operator should avoid side branch occlusion. A stent device with side holes would be able to occlude the aneurysm and allow perfusion of the side branch. If such a device is not available at the hospital in a situation requiring immediate treatment, the new DCA devices could be used to “shape” such a stent, as reported here in the Journal. However, we experienced negative results with the old directional coronary atherectomy devices and stent strut resection and recurrent balloon rupture thereafter.1 Alternatively, if IVUS shows involvement of the proximal side branch, a Y-stent could be used to cover that safely, but the angiogram makes this unlikely. Drug-eluting struts (DES) with late positive remodeling (RAVEL) and the absence of available side holes might render DES unsuitable. If IVUS shows that the lesion proximal to the RCA stent is induced by “neointima” or cellular substrates, DES or brachytherapy would be a therapeutic option, as the length of the treated vessel will be substantial. Post-interventional IVUS control should allow the operator to exclude device malapposition. Risk factors should definitely be re-evaluated and all should be treated adequately and aggressively (dose of statins, Lpa, homocysteine, collagen diseases...) to avoid further unnecessary complications.
References
1. Gonschior P, Christian V, Berthold H, Franz-Josef N. Rupture of an angioplasty balloon after treatment of a recurrent in-stent restenosis lesion of the left anterior descending coronary artery with directional coronary atherectomy. J Invas Cardiol 2000;12:105–108.