The New and Revised 2011 ACCF/AHA PCI and CABG Guidelines: A Revascularization Consensus is at the Heart of the Matter

The simultaneous publication of these two evidence based practice guidelines and their uniquely shared revascularization section represents an unprecedented joint effort by cardiologists and cardiovascular surgeons. The respective committees in conjunction with key members of the Stable Ischemic Heart Disease, STEMI and UA/NSTEMI guidelines should be congratulated on their thorough review of the relevant evidence, and balanced discussion of the merits of these two revascularization strategies in clinically relevant scenarios. Clinicians can now consult either guideline and find the best revascularization management strategy for their patients.

Additionally, readers will notice that an effort has been made to limit narrative text and employ summary and evidence tables with references for each recommendation for clarity and transparency. Revascularization strategies are divided between those indications intended to prolong survival, and those intended to improve symptoms. Most studies cited in this document reported results that historically were based on angiographic criteria (≥70% stenosis, ≥50% main left stenosis). Fractional flow reserve, when available was also considered. The Synergy Between Coronary Intervention With Taxus and Cardiac Surgery (SYNTAX) was used as a reasonable surrogate for the extent and complexity of CAD.

For patients with unprotected main left stenosis or complex CAD a “heart team” approach was recommended, in which an interventional cardiologist and a cardiothoracic surgeon would review the clinical material with the patient and make recommendations. The Syntax score and the Society for Thoracic Surgery (STS) database score could be incorporated into the decision making process. This approach has been shown to have lower patient mortality in concurrent registries than those patients randomly assigned to either PCI or CABG. PCI for significant mail left stenosis was up-graded from a Class IIb to a Class IIa Level of Evidence B recommendation in stable patients to improve survival compared to medical therapy when both the anatomic situation is favorable (those with low procedural risk and high likelihood of good long term outcome (e.g. SYNTAX score of ≤22, ostial or main left trunk disease), and the risk of cardiac surgery is significantly increased (STS score ≥5%). PCI for significant unprotected main left stenosis in the setting of UA/NSTEMI for patients who are not surgical candidates, and for patients with STEMI when there is a delay to, or increased risk of surgery and have a distal coronary TIMI flow grade of <3 on angiography also received a Class IIa recommendation.

CABG and PCI results for improvement of symptoms were reviewed in comparison to optimal medical therapy defined as guideline determined medical therapy (GDMT), acknowledging the contribution of the COURAGE trial. In general, revascularization was considered reasonable for patients with unacceptable angina despite GDMT.

CABG was compared to PCI for the various combinations of anatomic disease and left ventricular function for the indications of survival and symptom relief.

The findings for systemic reviews of PCI vs. medical therapy are summarized as follows:

• PCI has not been demonstrated to improve survival in stable patients.
• PCI reduces the incidence of angina PCI may increase the short term risk of MI PCI does not lower the long term risk of MI

A discussion of the evolving field of hybrid revascularization was included.

Procedural considerations for PCI emphasized adequate hydration while minimizing contrast administration in those patients with a creatinine clearance of <60 mL/min or less. N-acetyl L-cysteine is no longer recommended for the prevention of contrast induced acute kidney injury.

Anaphylactoid prophylaxis is recommended for patients with a previous reaction to contrast media, but not shellfish or seafood.

High dose, preprocedural statin administration received a Class IIa recommendation for prevention of peri-procedural MI.

The assessment of bleeding risk and glomerular filtration with appropriate adjustment in medication dosages was recommended for all patients.

Likewise, physicians should routinely record procedural radiation dosimetry (as well as plans for follow-up care) in cases with high procedural radiation dose.

The PCI writing committee reviewed institutional and patient specific criteria for primary and elective PCI in hospitals without surgical backup and listed these in easily referenced tables. These criteria are concordant with the standards of the Society for Cardiac Angiography and Interventions.

PCI in specific clinical situations (i.e., UA/NSTEMI, STEMI and cardiogenic shock), and anatomic situations (i.e., saphenous vein grafts with embolic protection, bifurcation lesions, chronic total occlusions etc.) is reviewed. Early - but not very early – angiography with intent for revascularization is recommended for high risk patients (Global Registry of Acute Coronary Events-GRACE score > 140).

The use of radial artery access to minimize bleeding complications and the choice of drug eluting stents (DES) vs. bare metal stents (BMS), and other adjunctive devises such as fractional flow reserve, intravascular ultrasound, rotational atherectomy, aspiration thrombectomy, vascular closure devices, cutting balloon, and the treatment of the “no reflow” phenomenon are all discussed.

Of particular importance is the summary and discussion of adjunctive pharmacotherapy including dual antiplatelet and anticoagulant medications. The use of tricagrelor has now been integrated into the guideline based on the findings of the Platelet Inhibition and Patient Outcome (PLATO) trial. Tricagrelor is a non thienopyridine p2y12 reversible inhibitor that achieved a significant 1.9% absolute risk reduction and a 16% relative risk reduction in the composite endpoint of vascular death, nonfatal MI, and non fatal stroke when compared with clopidogrel. There was no significant difference between the drugs for CABG related bleeding and the recommended time for withdrawal prior to CABG remains the same for clopidogrel and tricagrelor at 5 days. The drug has been approved for ACS patients but not for elective PCI or after fibrinolysis. Because the outcomes data from the North American cohort did not reach the same statistical outcomes as the entire study, and the dose of aspirin use generally in that cohort was higher than other geographic areas, the FDA has recommended that the low dose (81 mg) of aspirin be used with tricagrelor following loading.

The maintenance dose of aspirin after all PCI now has a Class IIa recommendation for the low dose (81 mg/day), since there is no superiority for higher doses and there is less bleeding.

The loading dose for clopidogrel by consensus is 600 mg, and the recommendations the dose and duration of therapy for prasugrel and clopidogrel remain unchanged from the 2009 ACCF/AHA focused update for STEMI and PCI.

There are several new and updated recommendations in the CABG guideline. Highlighting the procedural recommendations:

• The use of a trained professional for perioperative TEE in high risk cases, valvular heart disease or hemodynamically unstable patients.
• Considerations for the use of off pump-CABG vs. traditional on-pump CABG.
• Discussion of the systemic inflammatory response syndrome.
• The use of arterial conduits under various anatomic situations (e.g. the proscription against using a right internal mammary artery graft in a non critically stenosed right coronary artery).
• The use of minimally invasive access incisions.
• CABG under special clinical circumstances, such as acute MI or failed PCI.

For elective CABG, clopidogrel and tricagrelor should be discontinued for at least 5 days prior to surgery, and 7 days for prasugrel. For urgent CABG, clopidogrel and tricagrelor should be discontinued for at least 24 hours.

Beta blockers, if not contraindicated should be administered preoperatively, postoperatively and at discharge to prevent atrial fibrillation. Amiodarone may be used if beta blockers are contraindicated.

All cardiac surgery programs are advised to participate in risk-adjusted stat, regional and/or national registries.

The treatment of complications, and CABG for specific patient subsets such as the elderly, women, patients with diabetes, patients with anomalous coronary arteries, patients with end stage renal disease, chronic obstructive pulmonary disease, concomitant valvular surgery, repeat CABG, patients with peripheral arterial disease, and patients with previous stroke are all discussed with evidence review and recommendations in the guideline.

Finally, both economic considerations for CABG and CABG vs. PCI, as well as a discussion of future research needs round out the CABG guideline.