November 20, 2012 — Ischemic heart disease affects nearly 10 million Americans, and remains the leading cause of death among U.S. adults. This condition is most often due to a build-up of fat or plaque in the heart’s arteries that can reduce critical blood flow to the heart and often other parts of the body as well. With appropriate medical care, this condition remains stable in the vast majority of patients with few or no symptoms and the ability to pursue normal activities without limitations. Still, ongoing medical therapy and careful monitoring are essential to prevent heart attack and untimely death and should be based on strong scientific evidence and individual patient preferences.
The American College of Cardiology (ACC)/American Heart Association (AHA) Task Force on Practice Guidelines, along with the American College of Physicians (ACP), American Association for Thoracic Surgery (AATS), Preventive Cardiovascular Nurses Association (PCNA), Society for Cardiovascular Angiography and Interventions (SCAI), and The Society of Thoracic Surgeons (STS), jointly released comprehensive guidelines to provide clinicians with a framework to optimally care for patients with stable ischemic heart disease (SIHD).
The 170-page report presents an extensive assessment of the evidence and key issues involved in the diagnosis, risk assessment, treatment and follow up of known or suspected SIHD. Among the topics covered are guideline-directed medical therapy as the cornerstone of treatment for most patients; how to optimally care for women and other subgroups of patients who may be more prone to complications; the use of newer imaging and diagnostic technologies; the role of catheter-based and surgical procedures in treatment; the value of patient preferences in decision making; and the need for careful follow up to monitor for progression of disease and adherence to therapy.
“We have a phenomenal body of evidence about effective therapies both in terms of improving survival and quality of life,” said Stephan D. Fihn, M.D., MPH, division of general internal medicine at the University of Washington and chair of the 2012 writing committee. “These guidelines help identify those therapies that have been shown to possess benefit and those that have not, which can guide medical decision making.”
While an earlier ACC/AHA guideline on chronic stable angina that was issued in 2002 focused on specific drugs and interventions to reduce individual cardiovascular risk factors, the present document represents a more holistic view to managing SIHD. It also highlights key clinical considerations for certain subgroups of patients — in particular, women, older adults and people with diabetes and kidney disease — who may present with different symptoms and have worse outcomes in terms of cardiac events.
“Our thinking about this disease has evolved. We now better understand the interplay of risk factors involved in both the progression of the disease and the occurrence of adverse events such as heart attack and cardiac death,” said Fihn, who is also director, Office of Analytics and Business Intelligence at the Veterans Health Administration. “With this new guideline, we have transitioned from arbitrarily picking and choosing individual therapies to recognizing there is a package of lifestyle modifications and medications — what we call guideline-directed medical therapy — that benefits most patients.”
This “package” should ideally include an antiplatelet drug like daily aspirin (75-162 mg daily) and an appropriate dose statin in addition to heart healthy lifestyle changes. Therapy should also be tailored to individual patients to assure additional risk factors such as smoking, high blood pressure and diabetes are concurrently addressed.
The writing committee, which was comprised of diverse, multidisciplinary health care professionals spanning primary care, imaging and cardiology, including cardiac surgery, also took a stance on when to use more invasive strategies. For the vast majority of patients with stable disease — even those with considerable ischemia — medical management is warranted before considering revascularization by placing a stent in the blocked artery or through surgical bypass grafting.
“Overall, there is a misperception that somehow opening up and stenting an artery saves lives for patients with stable disease; however, in the majority of these cases there is no evidence from any study that this procedure prolongs life,” said Julius M. Gardin, M.D., cardiologist, professor and chair, department of medicine at Hackensack University Medical Center's and vice chair of the writing committee. He adds that even if clinicians identify a narrowing, they need to demonstrate the functional significance of that narrowing.
“The percent narrowing in and of itself isn’t as important as what it [the blockage] is doing downstream in terms of the heart getting — or not getting — enough nutrients,” said Gardin. “For this reason, we emphasize testing to show this, whether it’s through some of the non-invasive imaging tests or in the cath lab.” When such testing does show evidence of a severe blockage in patients on optimal medical therapy, and they are limited by their chest pain, coronary stenting or bypass surgery provides relief faster and at least as effectively as medicines. Of course, patients with stable symptoms should have the final say in how their chest pain is treated.
As in the previous guideline for patients with chronic stable angina, the standard treadmill stress test is still recommended as the first-line test for diagnosing SIHD or assessing the risk of death or complications in someone who can tolerate exercise and has a normal or interpretable ECG. However, because patients are now often older, more overweight/obese and perhaps unable to exercise, other imaging techniques such as nuclear myocardial perfusion imaging or echocardiography with pharmacologic stress are often needed. Routine annual stress and imaging studies are generally not recommended in stable patients unless there are changes in clinical circumstances. The guideline also highlights and identifies the limited niches where newer imaging technologies such as cardiac magnetic resonance and cardiac computed tomography might provide benefit.
Throughout the report, the writing committee stresses the need to inform patients and engage them in their own care, pointing to the value of shared decision making, which also considers personal preferences.
“Patient preference is very important in terms of directing care, so the answer may not be the same for every patient,” said Gardin. “Additionally, to provide quality care, we need to consistently devote time to each patient to educate them about the things that they can do in terms of self-care — stopping smoking, watching their diet, losing weight, getting regular exercise and taking their medications as prescribed.”
Although the writing committee was not expressly charged to evaluate the cost-effectiveness of specific recommendations, Fihn says clinicians who practice according to the recommendations based upon the strongest evidence and avoid expensive tests and treatments in circumstances for which there is little evidence will maximize value to patients and payers.
The new guideline was developed by experts at ACC and AHA in partnership with ACP, AATS, PCNA, SCAI, and STS without commercial support. The recommendations were also informed by discussions with other ACC writing committees to ensure consistency.