Left main coronary artery: Difference between revisions
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==Overview== | ==Overview== | ||
The left main coronary artery is the origin of the [[left coronary artery]] that lies between the aorta and the bifurcation of the left coronary artery into the [[left anterior descending artery]] and the [[left circumflex artery]]. It is 1 to 25 mm long, and is normally 3 to 5 mm wide. Severe narrowing of the left main coronary artery can result in death due to [[coronary ischemia]], and is an indication for [[coronary artery bypass grafting]] or [[coronary stenting]]. | The left main coronary artery is the origin of the [[left coronary artery]] that lies between the aorta and the bifurcation of the left coronary artery into the [[left anterior descending artery]] and the [[left circumflex artery]]. It is 1 to 25 mm long, and is normally 3 to 5 mm wide. Severe narrowing of the left main coronary artery can result in death due to [[coronary ischemia]], and is an indication for [[coronary artery bypass grafting]] or [[coronary stenting]]. | ||
==PCI in the Left Main Patient== | |||
In carefully selected patients, percutaneous [[LMCA|left main]] intervention can safely and effectively treat patients in whom [[coronary artery bypass graft]] [[surgery]] is a suboptimal option. Data from the [[SYNTAX]] trial supports such an approach. | |||
==Patient Selection== | |||
* Careful selection of patients for PCI is critical. | |||
* [[Fractional Flow Reserve|Fractional Flow Reserve (FFR)]] may be helpful in determining if a [[lesion]] is critical | |||
* [[Mortality]] and procedural results vary depending upon whether the [[lesion]] is [[ostium|ostial]] and/or in the shaft versus [[distal]] and involves the bifurcation. Thus, careful and meticulous [[angiography]] in multiple views is critical to fully assess the [[LMCA|left main]] at it's [[ostium]] and bifurcation. Optimal views include but are not limited to the AP caudal and the LAO Caudal. | |||
* [[CABG|Coronary Artery Bypass Grafting (CABG)]] is currently the standard of care for patients with [[LMCA|left main disease]]. However, this recommendation may be modified as data emerge regarding: | |||
# Very low in-hospital [[mortality]] among patients treated with [[LMCA|left main]] [[stent]]ing | |||
# Comparable or better MACE-free survival rates vs [[CABG]] in some registries | |||
# Low [[restenosis]] rate with [[drug eluting stent]] use | |||
===Appropriate Candidate for Left Main PCI=== | |||
#Nonoperative candidates | |||
#Low-risk patients who decline [[CABG]] | |||
#A patient who is both able and willing to take life long [[aspirin]] and [[clopidogrel]] ([[dual antiplatelet therapy]]) | |||
===High Risk Candidate for Left Main PCI=== | |||
:High-risk features in patients undergoing [[LMCA|left main]] disease PCI include: | |||
#Absence of [[saphenous vein]] or [[internal mammary artery]] [[graft]]s [[distal]]ly | |||
#Concomitant [[RCA]] disease | |||
#Lack of [[collateral]]s from [[RCA]] | |||
#[[Distal]] bifurcation involvement | |||
#[[LV dysfunction]] | |||
#Presence of [[clot]] | |||
#Extensive [[calcification]] | |||
== Technique == | |||
===Pre-interventional Preparation=== | |||
# The [[anatomy]] should be well characterized before the PCI | |||
# Evaluation of the potential to occlude or 'snowplow' a ramus is critical | |||
===Hemodynamic Monitoring and Support=== | |||
#[[Hemodynamic]] support with [[IABP|intra aortic balloon pump (IABP)]] placement is not mandatory, but should be considered for high-risk patients | |||
#If an [[IABP|Intra aortic balloon pump]] is not placed, consideration should be given to placement of a 4 or 5 French sheath in the [[contralateral]] [[groin]] in case one needs to be placed urgently | |||
#[[Percutaneous]] [[cardiopulmonary]] support (CPS) is an option for very-high-risk patient | |||
#[[Pulmonary artery line]] monitoring may be helpful | |||
===IVUS Use=== | |||
#Characterizes extent of [[plaque]] | |||
#Characterizes extent of [[calcification]] | |||
# Can be used to calculate the MLD/MLA (minimal [[lumen]] diameter/area) accurately and ascertain the significance of [[stenosis]] | |||
# [[QCA]] alone may not be adequate to determine the [[physiologic]] significance of an often eccentric [[LMCA|LM]] [[stenosis]] | |||
# [[IVUS]] may assist in sizing the [[stent]] appropriately to avoid [[stent]] malaposition and consequent higher risk of [[stent thrombosis]] and [[restenosis]] | |||
# In the presence of bifurcation disease you can use [[IVUS]] to determine the degree of [[plaque]] extent in the [[circumflex]] and use Murray's Law to calculate the [[stent]] size (diameter of the [[proximal]] main branch (diameter of [[distal]] main branch + diameter of [[distal]] side branch) X 0.67 | |||
===Guiding Catheter Selection=== | |||
# Use larger guiding catheters (i.e.: 7 or 8 French) in case [[distal]] bifurcation intervention becomes necessary | |||
# Select a guide that provides good support, but which can be backed out of the [[ostium]] if you are dealing with an [[ostium|ostial]] [[stenosis]] | |||
# Do not occlude [[ostium]] with the guide | |||
# Make side holes with an 18 gauge needle if necessary | |||
===Balloon Technique=== | |||
# Short [[occlusion]]/inflation times are critical to reduce [[ischemic]] time | |||
# Consideration should be given to a [[perfusion]] [[balloon]] in a very high risk patient and the [[distal]] tip should be placed in the [[LAD]]. | |||
# Select equipment in advance | |||
# Use a rapid exchange system | |||
# Dilute [[contrast]] in the indeflator to allow faster deflation | |||
===Stent Technique=== | |||
* Adequate [[stent]] sizing and post-[[dilation]] cannot be understated | |||
* [[Stent]] selection: | |||
** Consider using a [[drug eluting stent]] especially if the [[vessel]] is less than 4.5 mm | |||
** Good radial strength (larger Taxus [[stent]]s tend to recoil) | |||
** High visibility for [[ostium|ostial]] or bifurcation placement | |||
** Assure that [[aorta|aorto]]-[[ostium|ostial]] region covered by [[stent]] if there is [[ostium|ostial]] [[lesion]] ([[stent]] positioning in two orthogonal views is particularly important) | |||
===New Device Approaches to High Risk Lesion Morphologies=== | |||
* [[calcification|Calcified]] [[lesion]]s: | |||
** [[Rotational atherectomy]] | |||
** [[Stent]]ing | |||
* Bulky [[plaque]]: | |||
** Directional [[atherectomy]] + [[stent]]ing | |||
** [[Stent]]ing alone | |||
* [[Distal]] bifurcation involvement: | |||
** Similar to other bifurcation [[therapy|therapies]] but higher risk | |||
** DCA alone | |||
** DCA + [[stent]]ing of principal [[vessel]] | |||
** [[Stent]]ing of principal [[vessel]] (usually [[LAD]]) & rescuing [[circumflex]] | |||
** Bifurcation [[stent]]ing (V [[stent]]ing with kissing [[balloon]]s, crush or reverse crush, T [[stent]]ing, or Y, Culotte; in double barrel V or crush [[stent]]ing [[Left circumflex coronary artery|LCX]] limb is often the site of [[restenosis]] and re-crossing into the barrel is often challenging ) | |||
==Pharmacotherapy== | |||
* [[Antiplatelet]] regimen: | |||
# [[aspirin|ASA]] 325 mg PO prior to the procedure, use non-[[enteric coating|enteric coated]] to assure rapid [[absorption]] | |||
# [[Clopidogrel]] at a [[loading dose]] of 600 mg at least 2 hours prior to the intervention | |||
# [[Glycoprotein IIb/IIIa inhibitor]] administration is typical for this high risk [[lesion]] [[morphology]] | |||
* If [[UFH|unfractionated heparin]] ([[UFH]]) is used as an [[antithrombin]], then [[UFH]] should be dosed to achieve an [[activated clotting time|activated clotting time (ACT)]] of 250 seconds in the presence of a [[Glycoprotein IIb/IIIa inhibitor]] or 300 seconds in the absence of a [[Glycoprotein IIb/IIIa inhibitor]] | |||
==Sheath Removal== | |||
* A bad [[vagal reaction]] in a freshly implanted [[stent]] or in a patient awaiting PCI who has a significant [[LMCA|LM]] [[lesion]] can be very hazardous (risk of [[thrombosis]], or a downward spiral of poor [[perfusion]] leading to [[subendocardial]] [[ischemia]] leading to poorer [[LV function]], leading to poorer forward output). | |||
* Some operators will preemptively administer an [[ampule]] of [[atropine]] prior to the sheath pull or will have a low threshold to administer a full [[ampule]] of [[atropine]]. | |||
==Data Regarding The Efficacy and Safety of Left Main Stenting with Drug Eluting Stents<ref name="pmid17576862">Chieffo A, Park SJ, Valgimigli M, Kim YH, Daemen J, Sheiban I et al. (2007) [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=17576862 Favorable long-term outcome after drug-eluting stent implantation in nonbifurcation lesions that involve unprotected left main coronary artery: a multicenter registry.] ''Circulation'' 116 (2):158-62. [http://dx.doi.org/10.1161/CIRCULATIONAHA.107.692178 DOI:10.1161/CIRCULATIONAHA.107.692178] PMID: [http://pubmed.gov/17576862 17576862]</ref>== | |||
A [[retrospective]] multicenter registry study has demonstrated favorable long-term outcomes after the implantation of [[DES|drug eluting stents (DES)]] in non-bifurcation [[lesion]]s involving unprotected [[left main coronary artery|left main coronary arteries]]<ref name="pmid17576862">Chieffo A, Park SJ, Valgimigli M, Kim YH, Daemen J, Sheiban I et al. (2007) [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=17576862 Favorable long-term outcome after drug-eluting stent implantation in nonbifurcation lesions that involve unprotected left main coronary artery: a multicenter registry.] ''Circulation'' 116 (2):158-62. [http://dx.doi.org/10.1161/CIRCULATIONAHA.107.692178 DOI:10.1161/CIRCULATIONAHA.107.692178] PMID: [http://pubmed.gov/17576862 17576862]</ref>. | |||
The study, which was published in the online edition of [http://circ.ahajournals.org/ Circulation], examined registry data among 147 patients who were electively treated with percutaneous coronary intervention (PCI) with [[DES]] in unprotected [[left main coronary artery]] [[lesion]]s. | |||
At a median follow-up of 886 days, the major adverse [[cardiac]] event rate was 7.4% with a cumulative [[cardiac]] [[mortality]] of 2.7%. Only seven patients required target [[vessel]] [[revascularization]]. The [[restenosis]] rate at six-month [[angiographic]] follow-up was 0.9% with a late loss of -0.01 mm. Additionally, there were no [[angiographic]]ally proven cases of [[stent thrombosis]], although [[stent thrombosis]] could not be excluded in the four patients who died of unknown causes. | |||
While the results of the study suggest that the use of [[drug eluting stent]]s in nonbifurcation unprotected [[left main coronary artery]] [[stenosis]] is both safe and effective, Dr. Alaide Chieffo and colleagues note that the results are from a [[retrospective]] registry with a relatively small number of patients due to the low occurrence of this [[anatomy|anatomical]] subset. Currently there is no [[randomized control trial|randomized data]] comparing PCI with [[DES]] implantation versus [[coronary artery bypass graft]] [[surgery]]. The ongoing [[SYNTAX]] trial will evaluate 710 patients with [[LMCA|left main]] disease who have been randomized to either a [[DES]] or [[CABG]]. | |||
==Follow-up of the Patient with a DES in the Left Main== | |||
* [[LMCA|Left main]] [[restenosis]] may present as [[sudden death]] rather than recurrent [[angina]] | |||
* Screen aggressively for [[restenosis]] (with either [[angiography]] or Multi Detector CT for [[ostium|ostial]] disease) | |||
* Some operators perform [[platelet]] inhibition testing to confirm that the patient is not a [[clopidogrel]] non-responder. | |||
* Some operators dose the patient with 150 mg of [[clopidogrel]] per day in case the patient is a [[clopidogrel]] non-responder | |||
* Relook [[angiography]] recommended even in absence of sx at 2-3 months post-procedure to catch early [[restenosis]] and some operators recommend additional [[angiography]] at 6 months to identify late [[restenosis]] | |||
* [[coronary angioscopy|Angioscopy]] may aid in determining if [[clot]] is present at the end of the procedure, and if clot is present on repeat evaluation. | |||
==References== | |||
{{reflist|2}} | |||
[[Category:Up-To-Date]] | |||
[[Category:Up-To-Date cardiology]] | |||
[[Category:Cardiology]] | |||
{{WikiDoc Help Menu}} | |||
{{WikiDoc Sources}} | |||
==References== | ==References== | ||
Revision as of 17:44, 6 September 2013
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: LM, LMCA
Overview
The left main coronary artery is the origin of the left coronary artery that lies between the aorta and the bifurcation of the left coronary artery into the left anterior descending artery and the left circumflex artery. It is 1 to 25 mm long, and is normally 3 to 5 mm wide. Severe narrowing of the left main coronary artery can result in death due to coronary ischemia, and is an indication for coronary artery bypass grafting or coronary stenting.
PCI in the Left Main Patient
In carefully selected patients, percutaneous left main intervention can safely and effectively treat patients in whom coronary artery bypass graft surgery is a suboptimal option. Data from the SYNTAX trial supports such an approach.
Patient Selection
- Careful selection of patients for PCI is critical.
- Fractional Flow Reserve (FFR) may be helpful in determining if a lesion is critical
- Mortality and procedural results vary depending upon whether the lesion is ostial and/or in the shaft versus distal and involves the bifurcation. Thus, careful and meticulous angiography in multiple views is critical to fully assess the left main at it's ostium and bifurcation. Optimal views include but are not limited to the AP caudal and the LAO Caudal.
- Coronary Artery Bypass Grafting (CABG) is currently the standard of care for patients with left main disease. However, this recommendation may be modified as data emerge regarding:
- Very low in-hospital mortality among patients treated with left main stenting
- Comparable or better MACE-free survival rates vs CABG in some registries
- Low restenosis rate with drug eluting stent use
Appropriate Candidate for Left Main PCI
- Nonoperative candidates
- Low-risk patients who decline CABG
- A patient who is both able and willing to take life long aspirin and clopidogrel (dual antiplatelet therapy)
High Risk Candidate for Left Main PCI
- High-risk features in patients undergoing left main disease PCI include:
- Absence of saphenous vein or internal mammary artery grafts distally
- Concomitant RCA disease
- Lack of collaterals from RCA
- Distal bifurcation involvement
- LV dysfunction
- Presence of clot
- Extensive calcification
Technique
Pre-interventional Preparation
- The anatomy should be well characterized before the PCI
- Evaluation of the potential to occlude or 'snowplow' a ramus is critical
Hemodynamic Monitoring and Support
- Hemodynamic support with intra aortic balloon pump (IABP) placement is not mandatory, but should be considered for high-risk patients
- If an Intra aortic balloon pump is not placed, consideration should be given to placement of a 4 or 5 French sheath in the contralateral groin in case one needs to be placed urgently
- Percutaneous cardiopulmonary support (CPS) is an option for very-high-risk patient
- Pulmonary artery line monitoring may be helpful
IVUS Use
- Characterizes extent of plaque
- Characterizes extent of calcification
- Can be used to calculate the MLD/MLA (minimal lumen diameter/area) accurately and ascertain the significance of stenosis
- QCA alone may not be adequate to determine the physiologic significance of an often eccentric LM stenosis
- IVUS may assist in sizing the stent appropriately to avoid stent malaposition and consequent higher risk of stent thrombosis and restenosis
- In the presence of bifurcation disease you can use IVUS to determine the degree of plaque extent in the circumflex and use Murray's Law to calculate the stent size (diameter of the proximal main branch (diameter of distal main branch + diameter of distal side branch) X 0.67
Guiding Catheter Selection
- Use larger guiding catheters (i.e.: 7 or 8 French) in case distal bifurcation intervention becomes necessary
- Select a guide that provides good support, but which can be backed out of the ostium if you are dealing with an ostial stenosis
- Do not occlude ostium with the guide
- Make side holes with an 18 gauge needle if necessary
Balloon Technique
- Short occlusion/inflation times are critical to reduce ischemic time
- Consideration should be given to a perfusion balloon in a very high risk patient and the distal tip should be placed in the LAD.
- Select equipment in advance
- Use a rapid exchange system
- Dilute contrast in the indeflator to allow faster deflation
Stent Technique
- Adequate stent sizing and post-dilation cannot be understated
- Stent selection:
- Consider using a drug eluting stent especially if the vessel is less than 4.5 mm
- Good radial strength (larger Taxus stents tend to recoil)
- High visibility for ostial or bifurcation placement
- Assure that aorto-ostial region covered by stent if there is ostial lesion (stent positioning in two orthogonal views is particularly important)
New Device Approaches to High Risk Lesion Morphologies
- Calcified lesions:
- Bulky plaque:
- Directional atherectomy + stenting
- Stenting alone
- Distal bifurcation involvement:
- Similar to other bifurcation therapies but higher risk
- DCA alone
- DCA + stenting of principal vessel
- Stenting of principal vessel (usually LAD) & rescuing circumflex
- Bifurcation stenting (V stenting with kissing balloons, crush or reverse crush, T stenting, or Y, Culotte; in double barrel V or crush stenting LCX limb is often the site of restenosis and re-crossing into the barrel is often challenging )
Pharmacotherapy
- Antiplatelet regimen:
- ASA 325 mg PO prior to the procedure, use non-enteric coated to assure rapid absorption
- Clopidogrel at a loading dose of 600 mg at least 2 hours prior to the intervention
- Glycoprotein IIb/IIIa inhibitor administration is typical for this high risk lesion morphology
- If unfractionated heparin (UFH) is used as an antithrombin, then UFH should be dosed to achieve an activated clotting time (ACT) of 250 seconds in the presence of a Glycoprotein IIb/IIIa inhibitor or 300 seconds in the absence of a Glycoprotein IIb/IIIa inhibitor
Sheath Removal
- A bad vagal reaction in a freshly implanted stent or in a patient awaiting PCI who has a significant LM lesion can be very hazardous (risk of thrombosis, or a downward spiral of poor perfusion leading to subendocardial ischemia leading to poorer LV function, leading to poorer forward output).
- Some operators will preemptively administer an ampule of atropine prior to the sheath pull or will have a low threshold to administer a full ampule of atropine.
Data Regarding The Efficacy and Safety of Left Main Stenting with Drug Eluting Stents[1]
A retrospective multicenter registry study has demonstrated favorable long-term outcomes after the implantation of drug eluting stents (DES) in non-bifurcation lesions involving unprotected left main coronary arteries[1].
The study, which was published in the online edition of Circulation, examined registry data among 147 patients who were electively treated with percutaneous coronary intervention (PCI) with DES in unprotected left main coronary artery lesions.
At a median follow-up of 886 days, the major adverse cardiac event rate was 7.4% with a cumulative cardiac mortality of 2.7%. Only seven patients required target vessel revascularization. The restenosis rate at six-month angiographic follow-up was 0.9% with a late loss of -0.01 mm. Additionally, there were no angiographically proven cases of stent thrombosis, although stent thrombosis could not be excluded in the four patients who died of unknown causes.
While the results of the study suggest that the use of drug eluting stents in nonbifurcation unprotected left main coronary artery stenosis is both safe and effective, Dr. Alaide Chieffo and colleagues note that the results are from a retrospective registry with a relatively small number of patients due to the low occurrence of this anatomical subset. Currently there is no randomized data comparing PCI with DES implantation versus coronary artery bypass graft surgery. The ongoing SYNTAX trial will evaluate 710 patients with left main disease who have been randomized to either a DES or CABG.
Follow-up of the Patient with a DES in the Left Main
- Left main restenosis may present as sudden death rather than recurrent angina
- Screen aggressively for restenosis (with either angiography or Multi Detector CT for ostial disease)
- Some operators perform platelet inhibition testing to confirm that the patient is not a clopidogrel non-responder.
- Some operators dose the patient with 150 mg of clopidogrel per day in case the patient is a clopidogrel non-responder
- Relook angiography recommended even in absence of sx at 2-3 months post-procedure to catch early restenosis and some operators recommend additional angiography at 6 months to identify late restenosis
- Angioscopy may aid in determining if clot is present at the end of the procedure, and if clot is present on repeat evaluation.
References
- ↑ 1.0 1.1 Chieffo A, Park SJ, Valgimigli M, Kim YH, Daemen J, Sheiban I et al. (2007) Favorable long-term outcome after drug-eluting stent implantation in nonbifurcation lesions that involve unprotected left main coronary artery: a multicenter registry. Circulation 116 (2):158-62. DOI:10.1161/CIRCULATIONAHA.107.692178 PMID: 17576862