The ACC/AHA Guidelines: What's New
NEW ORLEANS, LA—New recommendations are indicated for the treatment of extracranial carotid and vertebral artery disease (ECVD), UA/NSTEMI, and hypertrophic cardiomyopathy (HCM), according to several researchers who discussed the recent 2011 changes to the American College of Cardiology/American Heart Association (ACC/AHA) guidelines at a symposium during ACC.11, the American College of Cardiology's 60th Scientific Session.
Extracranial Carotid and Vertebral Artery Disease (ECVD) Guidelines
Jonathan L. Halperin, MD, Mt. Sinai Medical Center, New York, NY, and Thomas Brott, MD, Mayo Clinic, Jacksonville, FL, presented several key updates to the ACC/AHA guidelines for ECVD. In asymptomatic patients with known or suspected carotid stenosis, duplex ultrasonography is now recommended as the initial diagnostic test to detect hemodynamically significant carotid stenosis. However, it is not recommended for the routine screening of asymptomatic patients who have no clinical manifestations of or risk factors for atherosclerosis.
In patients who have symptoms or signs of ECVD, initial evaluation should include noninvasive imaging for the detection of ECVD. In patients who exhibit symptoms corresponding to the territory supplied by an internal carotid artery, magnetic resonance angiography (MRA) or computed tomography angiography (CTA) is indicated when sonography either cannot be obtained or yields equivocal or otherwise non-diagnostic results. In addition, “Aspirin alone, clopidogrel alone, or the combination of aspirin plus extended-release dipyridamole is recommended and preferred over the combination of aspirin with clopidogrel,” said Dr. Brott,
Antiplatelet agents are recommended over oral anticoagulation in patients with or without ischemic symptoms. In addition, it may be beneficial to administer a vitamin K antagonist (eg, dose-adjusted warfari)n to patients with atrial fibrillation or a mechanical prosthetic heart valve in order to achieve a target INR of 2.5 (range 2–3).
In terms of treatment, the guidelines recommend that patients at average or low surgical risk should undergo carotid endarterectomy (CEA) if the diameter of the lumen of the ipsilateral internal carotid artery is reduced by more than 50–70%. Carotid artery stenting (CAS) is indicated as an alternative to CEA in symptomatic patients at average or low risk of complications associated with endovascular intervention.
The guidelines also state that is reasonable to perform CEA in asymptomatic patients who have more than 70% stenosis. They also state that it is reasonable to choose CEA over CAS in older patients, especially when arterial pathoanatomy is unfavorable. The effectiveness of CAS in asymptomatic patients or in high-risk patients with or without symptoms is not well established. Dual-antiplatelet therapy with aspirin and clopidogrel is recommended before and for at least 30 days after CAS.
Scott Wright, MD and Jeffrey L. Anderson, MD discussed changes to the UA/NSTEMI guidelines. When PCI is planned, thienopyridine is recommended for patients with UA/NSTEMI; regimens should include either clopidogrel 300–600mg as early as possible or at the time of PCI, or prasugrel 60mg promptly and no later than 1 hour after PCI. In patients with UA/NSTEMI undergoing PCI, clopidogrel 75mg daily or prasugrel 10mg daily should be given for at least 12 months. Medication may be discontinued if the risk of mortality due to bleeding outweighs the anticipated benefits of thienopyridine therapy.
The guidelines also state that upstream GP IIb/IIIa inhibitors should not be used in UA/NSTEMI patients at low risk for ischemic events or at high risk of bleeding who are already receiving ASA and clopidogrel. Prasugrel may be harmful to patients with a prior history of stroke and/or TIA for whom PCI is planned.
Clopidogrel or prasugrel may be continued for longer than 15 months in patients following DES placement, said Dr. Anderson. In patients with chronic kidney disease who have UA/NSTEMI, CrCl should be estimated and the doses of renally cleared medications should be adjusted accordingly. An invasive strategy is reasonable in patients with mild (stage II) and moderate (stage III) CKD.An insulin-based regimen may be used to achieve and maintain glucose levels <180mg/dL for hospitalized patients with diabetes and UA/NSTEMI (in either a complicated or uncomplicated course).
It is reasonable to use an early invasive strategy (within 12–24 hours of admission) over a delayed invasive strategy for initially stabilized high-risk patients who have UA/NSTEMI. A delayed approach is reasonable in patients with no risk.
Hypertrophic Cardiomyopathy (HCM) Guidelines
Barry J. Maron, MD, FACC, Co-Chair of the ACC/AHA Task Force on Practice Guidelines Writing Committee, noted how rare HCM studies are because it is a heterogeneous condition that is relatively uncommon in cardiologic practice and has a low event rate. Despite the lack of data, the revised guidelines are more systematic and contain more specific recommendations and levels of evidence.
Dr. Maron states that ”the greatest value of genetic testing for HCM is found in family screening, which has the potential for a definitive positive or negative diagnosis.” The guidelines state that HCM is best managed by: 1) screening first-degree relatives, 2) assessing risk for and preventing SCD, 3) avoiding competitive sports and exercise, and 4) controlling symptoms.
Myectomy is now indicated if LVOT obstruction occurs; if angina, dyspnea, and/or syncope significantly reduce quality of life; and if symptoms persist despite medical therapy. After surgical septal myectomy, observational data suggests that HCM-related and SCD mortality rates are better than expected, said Bernard J. Gersh, MD, ChB, DPhil, FACC, FAHA, Co-Chair of the ACC/AHA Task Force on Practice Guidelines Writing Committee. However, there is no data that confirms mortality benefit as the sole indication for myectomy.
It is recommended that ablation be used in the case of LVOT obstruction; if symptoms persist despite medical therapy; if the patient is a suboptimal surgery candidate; and if the patient prefers it after a balanced discussion, said Dr. Maron. However, the chance of procedural complications is greater for ablation compared to myectomy. Patients ≤65 years have better symptom resolution with myectomy. Although no impairment in short-term survival was seen with ablation, its long-term effects are still unknown.