Total Occlusion of Left Main Coronary Artery in NSTE-ACS Patient : A Case Report

Author : D.U. Setyowati, A. Kailani, M. Silalahi, M. Zaini
Upload Date : 19-04-2018

Background: Total occlusion of left main coronary artery (LMCA) is an unusual manifestation of coronary atheromatous disease. Total left main coronary artery occlusion can be either acute or chronic. Acute total LMCA occlusion is usually associated with higher mortality, presenting with extensive acute myocardial infarction, cardiogenic shock or sudden cardiac death.1,3 Patients who survive to present with either acute or chronic complete LMCA occlusion consist of a selective group, as a high mortality is already associated with subtotal narrowing of the vessel. Total occlusion of LMCA is rare in patients undergoing coronary angiography, because it usually results in sudden death. The incidence of it ranges from 0.04 to 0.43 %.6 Most patients with acute total occlusion of the LMCA suffer extensive transmural myocardial infarction. Acute LMCA obstructions resulting in minimal myocardial damage or in a non-Q-wave infarction have rarely been reported.4

Objective: To present a case of a Total Occlusion in patient, without meet ST segment elevation at ECG test.

 Case Illustration: A 55-years old woman, presents to the Emergency Department (ED) after two week of chest discomfort, lethargic, accompanied with shortness of breathing. She felt heaviness, tightness, and burning sensation on the chest. It was more intense, easily provoked by mild activity, but still responded to rest. 1 day before admission it become more frequent, severe than the usual chest discomfort.  It occurred for more than 15 mins. She also complained about having nausea and vomiting. She has a medical history of 5 years uncontrolled hypertension. She did not take any routine hypertension drug since then. Especially for the past few years she has not seen her internist anymore. When she feel unhealthy, she simply went straight to drug stores and took hypertension drug without any prescription, nor seeing the physicians. Her vital sign shows quite unstable hemodynamic status, which are 90/75 mmHg for blood pressure test, 117 beats per minute heart rate, 22 breaths per minute respiratory rate, and blood oxygen saturation level is 98%. On physical examination, there was no elevated jugular venous pressure, nor any abnormality for the cardiopulmonary region. Clammy foot with lower peripheral perfusion was found. 27,74 detected for the Troponin I level test. Cardiomegaly on CXR results. ECG shows tachicardial sinus with depression on ST segment of 3 mm at II, III, AVF lead, QS on V1-V4, Ischemia inferior wall with Old MCI. Echocardiography shows LVH concentric with EF 41% and grade II diastolic dysfunction. TIMI risk score was 4. Then, she was diagnosed with Non-STEACS, got oxygen supply, Ringer Lactate infusion, 5 mg ISDN, 300 mg Clopidogrel and 160 mg Aspilets and 20 mg Furosemide injection. The she delivered to cath lab to having a Rescued PCI. Unexpectedly, while performing coronary angiography, total occlusion has been found on the mid-distal LM, LAD, LCX ostium, and 50% stenosis on the RCA ostium. TIMI 3 flow after undergo Rescued percutaneous coronary intervention (PCI) on the mid LAD and LM-proximal LCX. Evaluation by serial ECG showed a resolution on ST segment and clinical manifestation as well.

Discussion: In a vast majority of the patients, a significant decrease of left ventricular function is immediately encountered, followed by cardiogenic shock and severe ventricular arrhythmias. The management is based on urgent reestablishment of coronary flow. Emergency utilization of intracoronary thrombolysis, left main balloon angioplasty, and insertion of an intra-aortic balloon pump (IABP) are among the recommended urgent means of revascularization. Although a review of the literature can initially give the impression that attempts at emergent mechanical revascularization are commonly associated with survival, and at times with only minimal myocardial damage, one should be aware that there is a tendency to report only successful outcomes of acute interventions. Even with successful emergency balloon angioplasty, some patients do not survive the postoperative period as a result of extensive myocardial damage and subsequent multisystem failure. Survival with non-interventional, conservative medical management is extremely rare.4

Typical ECG findings with LMCA occlusion can show a widespread horizontal ST depression, most prominent in leads I, II and V4-6; ST elevation in aVR ≥ 1mm; and ST elevation in aVR ≥ V1. Meanwhile this patient’s ECG shown an ST segment depression at II, III, AVF lead, QS on V1-V4. Significant disease (>50% narrowing) of the left main coronary artery is reported in approximately 5% of patients undergoing coronary arteriography, while total occlusion of the left main coronary artery is an infrequent finding.2 Patients who do not die during the acute phase of total occlusion usually have a dominant right coronary artery and extensive collateral circulation to the left coronary artery.7 We can concluded that there is direct evidence that collateral vessels can at least partially compensate for the loss of normal coronary flow, and it is not reasonable to infer that she may be functionless from the angiographic evidence. This cases which failed to show collateral flow preinfarction, had evidence of significant LV dysfunction (ejection fraction of 41%) after sustaining an acute nontransmural myocardial infarction. Consequently, cardiac output is very low and most patients, especially those with acute closure, need intra-aortic balloon counter-pulsation for hemodynamic support. But fortunately she has a great collateral artery from RCA that fulfill the LMCA area’s oxygen demand. This explained why ST depression on the inferior site was formed as a reciprocal change from the anterior part. Apart from facilities availability and her syntax score is 33, whereas for this patient we did an emergency rescued PCI due to life saving matter. She discharged after 6 days of treatment care and seeing cardiologist in a stable condition.

Conclusion: The rarity with which total LMCA occlusion is seen suggests this may be a terminal event in many patients in whom it occurs. Survival may be dependent on the rate at which occlusion of the LMCA occurred. Gradual development of occlusion may allow for functional collaterals to develop survival chance. Total occlusion of the LMCA represents a unique clinical condition with specific angiographic characteristics. Symptoms correspond to the presence and qualities of collateral vessels, associated myocardial damage, and impaired hemodynamics.2 The ability of collaterals to maintain myocardial demand is affected by the extent of atherosclerotic disease in the collaterals donor artery. In acute cases, the management includes immediate restoration of left main blood flow and hemodynamic support by mechanical interventional means such as balloon angioplasty and IABP, commonly followed by surgical revascularization. CABG surgery has long been the standard of care for patients with LMCA disease, whereas PCI was only performed as salvage treatment. However, over time, the PCI treatment has undergone considerable therapeutic evolution. Remarkable advancements in stent technology, technical refinement, and adjunctive drug therapy have led to progressively improved PCI outcomes for LMCA disease.4,5

KEYWORDS : Left Main Coronary Artery Occlusion, Collateral Vessel, Non-STEACS, Intra-Aortic Balloon Pump

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