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C32 Cardiology and Cardiac Surgery
Ischemic Heart Disease Toronto Notes 2019
Adjunctive Therapies
• ASAandheparindecreasepost-proceduralcomplications
• furtherreductioninischemiccomplicationshasbeendemonstratedusingGPIIb/IIIainhibitors
(abciximab, eptifibatide, tirofiban) in coronary angiography and stenting • followingstentimplantation
■ dual antiplatelet therapy (ASA and clopidogrel) for 1 mo with BMS or ≥12 mo with DES ■ DAPT study showed benefit of dual antiplatelet therapy beyond 12 mo
■ ASA and prasugrel can be considered for those at increased risk of stent thrombosis
Procedural Complications
• mortalityandemergencybypassrates<1% • nonfatalMI:approximately2-3%
CORONARY ARTERY BYPASS GRAFT SURGERY
• objectiveofCABGiscompletereperfusionofthemyocardium
Indications
• CABG
■ ≥50% diameter stenosis in the left main coronary artery
■ ≥70% diameter stenosis in three major coronary arteries
■ ≥70% diameter stenosis in the proximal LAD artery plus one other major coronary artery
■ survivors of sudden cardiac arrest with presumed ischemia-mediated VT caused by significant
(≥70% diameter) stenosis in a major coronary artery • other
■ ≥70% diameter stenosis in two major coronary arteries (without proximal LAD disease) and evidence of extensive ischemia
■ ≥70% diameter stenosis in the proximal LAD artery and evidence of extensive ischemia
■ multivessel CAD in patients with diabetes
■ LV systolic dysfunction (LVEF 35% to 50%) and significant multivessel CAD or proximal LAD
stenosis where viable myocardium is present in the region of intended revascularization • PCI
■ UA/NSTEMI if not a CABG candidate
■ STEMI when PCI can be performed more rapidly and safely than CABG • CABGorPCI
■ one or more significant (≥70% diameter) coronary artery stenosis amenable to revascularization and unacceptable angina despite medical therapy
Duration of Triple Therapy in Patients Required Oral Anticoagulation (OAC) After Drug-Eluting Stent Implantation: The ISAR-TRIPLE Trial. Journal of the American College of Cardiology 66.9 (2015):1088-1089
Study: RCT comparing whether shortening the duration of clopidogrel therapy from 6 months to 6 weeks after DES implantation was associated with superior net clinical outcome in patients receiving concomitant aspirin and OAC.
Population: 614 patients from 3 European centres receiving DES implantation on OAC and aspirin. Intervention: 6 week vs. 6 month clopidogrel therapy post-DEC
Outcome: Death, myocardial infarction, definite stent thrombosis, stroke, thrombolysis in myocardial infraction major bleeding at 9 months Results: Primary endpoint occurred in 9.8% in 6 week group vs. 27 patients in 6 month group (HR: 1.14; 95% CI: 0.68-1.91; p-0.63)
Conclusions: Six weeks of triple therapy is not superior to 6 months. Physician should weigh trade-off between ischemic and bleeding risk when choosing shorter or longer duration of triple therapy.
Table 10. Choice of Revascularization Procedure
PCI
Less invasive technique
Decreased periprocedural morbidity and mortality Shorter periprocedural hospitalization
Single or double-vessel disease Inability to tolerate surgery
Percutaneous Coronary Intervention vs. Coronary-Artery Bypass Grafting for Severe Coronary Artery Disease: The SYNTAX Trial NEJM 2009;360;961-972
Study: Prospective RCT.
Population: 1,800 patients with untreated three- vessel or left main coronary artery disease and anatomically equivalent for both Percutaneous Intervention (PCI) and Coronary Artery Bypass Graft (CABG).
Intervention: PCI vs. CABG.
Outcome: Composite of death from any cause, stroke, MI, or repeat revascularization in 12 mo post-intervention.
Results: Incidence of primary outcome was lower in the CABG intervention vs. PCI (12.4% vs. 17.8%, p=0.002, NNT=19). PCI was associated with significantly higher rates of repeat revascularization (13.5% vs. 5.9%, p<0.001) and cardiac death (3.7% vs. 2.1%, p=0.05), while CABG had higher rates of stroke (2.2% vs. 0.6%, p=0.03).
Conclusions: In patients with three-vessel or left main coronary artery disease CABG is superior to PCI in preventing major adverse cardiovascular
and cerebrovascular events within 12 mo of intervention.
Advantages
Indications
CABG
Greater ability to achieve complete revascularization Decreased need for repeated revascularization procedures
Triple-vessel or left main disease
DM
Plaque morphology unfavourable for PCI
Considerations
Used when arterial grafts are not available or many grafts are required, such as triple or quadruple bypass
Most preferred option because of excellent patency Improved event-free survival (angina, MI) Decreased late cardiac events
No increase in operative risk
Used in bilateral ITA/IMA grafting
Patients receiving bilateral ITAs/IMAs have less risk of recurrent angina, late MI, angioplasty
Prone to severe vasospasm post-operatively due to muscular wall
Primarily used as an in situ graft to bypass the RCA
Use limited because of the fragile quality of the artery, other technical issues, increased operative time (laparotomy incision), and incisional discomfort with associated ileus
For younger patients (<60 yr of age)
Is preferred due to longer term graft patency
Operative mortality 2-3x higher than first operation
10% perioperative MI rate
Reoperation undertaken only in symptomatic patients who have failed medical therapy and in whom angiography has documented progression of the disease
Increased risk with redo-sternotomy secondary to adhesions which may result in laceration to aorta, RV,
IMA/ITA, and other bypass grafts
Table 11. Conduits for CABG
Graft
Saphenous Vein Grafts
(SVG)
Left Internal Thoracic/Mammary Artery (LITA/LIMA) (LIMA to LAD)
Right Internal Thoracic/ Mammary Artery (RITA/RIMA)
Radial Artery (free graft) Right Gastroepiploic
Artery
Complete Arterial Revascularization
Redo Bypass Grafting
Occlusion/Patency Rate
At 10 yr, 50% occluded, 25% stenotic, 25% angiographically normal
90-95% patency at 15 yr
Pedicled RIMA patency comparable to LIMA
Free RIMA patency less
85-90% patency at 5 yr 80-90% patency at 5 yr