Percutaneous Unprotected Left Main Coronary Artery Interventions
Acute Unprotected Left Main Coronary Artery Occlusion in the Setting of ST-elevation Myocardial Infarction – Is Percutaneous Coronary Intervention the Preferred Revascularisation Approach?
Acute occlusion involving the ULMCA accounts for 0.8% of patients who undergo primary PCI.63
This event is often associated
indicate that PCI and CABG have a class Ia indication in patients with cardiogenic shock, but do not provide specific treatment recommendations for ULMCA disease.
with catastrophic events such as cardiogenic shock, lethal arrhythmias and sudden death. Uncertainty surrounds the optimal revascularisation strategy for ST-elevation MI (STEMI) patients due to acute ULMCA occlusion. The revised 2004 American College of Cardiology (ACC)/American Heart Association (AHA) STEMI guidelines64
Data from individual trials with small sample sizes show a high mortality rate for patients with STEMI and ULMCA acute occlusion regardless of the revascularisation strategy chosen. The in-hospital mortality rate of STEMI patients with ULMCA occlusion treated with primary PCI ranges between 35 and 44%,65–67
emergency CABG in the same clinical setting.68
while a rate of 46% was reported after Although data on long-
term follow-up are limited, patients who survive to discharge following ULMCA PCI have a favourable prognosis in terms of subsequent death and MI.65–67
However, considering the high clinical risk profile of this subset of patients, a treatment bias favouring PCI over CABG prohibits direct comparison between the two revascularisation modalities. Moreover, it is unlikely that a randomised controlled trial with sufficient size for this indication will be conducted given the logistical complexity of such a study and the treatment biases that favour one therapy over another. Nevertheless, there is an opportunity through studies to further refine our understanding of ULMCA PCI in STEMI.
PCI may be performed more expeditiously than CABG to promptly reperfuse the infarcted artery, potentially reversing arrhythmic and haemodynamic instability. Delays to reperfusion with CABG, which may take one hour or longer during off-peak hours to establish cardiopulmonary bypass, can be catastrophic in this situation. Hence, emergency PCI performed in a timely fashion by experienced operators should be considered as a preferred alternative to CABG in the following situations:64
ULMCA occlusion with a Thrombolysis In
Myocardial Infarction (TIMI) flow grade less than 3; cardiogenic shock and/or life-threatening arrhythmias; or co-morbidities that pose an excessive risk of CABG-related complications such as chronic obstructive pulmonary disease, cerebrovascular disease.69
Is Intravascular Ultrasound Guidance Needed for Unprotected Left Main Coronary Artery Percutaneous Coronary Intervention? Evaluation of ULMCA disease may be difficult because of anatomical and haemodynamic factors such as large size, overlapping major vessels, aortic cusp opacification and varied angulations. There is a need for proper evaluation of both the distribution and disease severity in cases of ULMCA lesions. Therefore, haemodynamic and intravascular ultrasound (IVUS) assessment of ULMCA disease has associated the functional and/or anatomical relevance of stenosis with the need for treatment and clinical outcome.70,71
Although a small retrospective study reported that IVUS-guided ULMCA PCI with DES did not have a significant clinical long-term
INTERVENTIONAL CARDIOLOGY benefit compared with angiography guided PCI,46 the usefulness of
IVUS-guided stenting may not be hampered by this underpowered retrospective study. Angiography has a clear limitation in assessing the true luminal size of ULMCA, because the left main artery is often short and lacks a normal segment for comparison. In addition to the assessment of an ULMCA lesion before the procedure, IVUS guidance is helpful to obtain an adequate expansion of DES, prevent stent malapposition and achieve full lesion coverage with DES. A subgroup analysis from the MAIN-COMPARE registry reported that IVUS guidance was associated with improved three-year mortality rates compared with conventional angiography-guided procedures after adjustment with propensity-score matching (6.3% IVUS versus 13.6% angiography, log rank p=0.063, HR 0.54, 95% CI 0.28–1.03).27
In
particular, for patients receiving DES, IVUS-guided PCI was associated with a significantly lower three-year incidence of mortality compared with angiographically guided PCI (4.7% IVUS versus 16% angiography, log rank p=0.048, HR 0.39, 95% CI 0.15–1.02).27
Despite the
non-randomised design of the study, these results indicate that IVUS-guided PCI for ULMCA disease may play a significant role in reducing ST and long-term mortality. IVUS assessment of stent underexpansion, incomplete lesion coverage, suboptimal stent area and incomplete stent apposition have been found to predict early and late/very late ST after DES implantation.72–76
Therefore, IVUS-guided PCI
with DES for ULMCA stenosis should be strongly recommended. Finally, optimal coherence tomography (OCT) to assess vascular response to LMCA stenting has recently been reported.77
Are Clinical Safety and Efficacy Equivalent for the Various Drug-eluting Stents in Unprotected Left Main Coronary Artery Percutaneous Coronary Intervention?
To date, data are mostly limited to sirolimus-eluting stents (SES) and PES. Several small observational studies have compared outcomes following SES or PES implantation for ULMCA stenting, showing similar results at mid-term follow-up.17,47
In the Intracoronary stenting and angiographic results: drug-eluting stents for unprotected left main lesions (ISAR-LEFT MAIN) randomised trial,37
607 patients were assigned to ULMCA PCI with SES or PES to compare the one-year composite outcome of death, MI and TLR. At 12- month follow-up, no significant differences were reported in the one- year primary end-point (PES 13.6% versus SES 15.8%, relative risk 0.85, 95% CI 0.56–1.29), angiographic restenosis (six- to nine-month follow-up: PES 16% versus SES 19.4%; p=0.30) and two-year left main specific revascularisation rates (9.2% PES versus 10.7% SES; p=0.47). The incidence of definite (0.7% PES versus 0.3% SES) and probable (0.3% PES versus 0% SES) ST was also similar in the two groups at two-year follow-up.37
Although promising results have been demonstrated with new-generation DES in selected and unselected subsets of patients and lesions, only limited data are as yet available regarding their safety and efficacy in ULMCA PCI. In the Left main Taxus and left main Xience (LEMAX) non-randomised registry, 173 patients with ULMCA disease treated with an everolimus-eluting stent (EES) (Xience V; Abbott Vascular, Santa Clara, CA, US) were compared with a historical cohort of 291 patients treated with PES (Taxus, Boston Scientific, Natick, MA, US) for ULMCA stenosis. At 12-month clinical follow-up, the EES was associated with a lower rate of target lesion failure (a composite of cardiac death, target
47
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100