Published studies have shown that there is a strong link between hypertension and coronary artery disease (CAD). Hypertension has been identified as is a major independent risk factor for the development of CAD, stroke, and renal failure. Despite increasing knowledge of the benefits of antihypertensive agents, the optimal choice of these medications remains controversial. Furthermore, there are many important lingering questions regarding the optimal treatment of hypertension to prevent and help manage ischemic heart disease.
The American Heart Association, American College of Cardiology, and American Society of Hypertension have issued a scientific statement to address the treatment of hypertension among patients with established CAD. The statement, available for free online at http://hyper.ahajournals.org, was published jointly in Circulation, Hypertension, the Journal of the American College of Cardiology, and the Journal of the American Society of Hypertension. The writing committee consisted of internationally recognized experts in the fields of cardiology and hypertension research.
According to Clive Rosendorff, MD, PhD, DScMed, who chaired the writing group that developed the scientific statement, a general target blood pressure (BP) of less than 140/90 is recommended to prevent heart attacks and strokes in patients with hypertension and established CAD. “It’s important to note, however, that there are different types of heart disease that may warrant slight changes in BP targets,” he says. Clarifying BP goals is especially important because there has been some confusion regarding the appropriate targets for BP management in the general population.
The scientific statement notes that a target BP of less than 140/90 is reasonable to avoid heart attacks and strokes, but stipulates that a lower target of less than 130/80 may be appropriate in some individuals with CAD who have already experienced a stroke, heart attack, or transient ischemic attack. This lower target may also be appropriate for patients with other cardiovascular conditions, such as those with peripheral arterial disease or abdominal aortic aneurysms (Table).
“When considering a lower BP target, decisions often are left to the discretion of physicians,” says Dr. Rosendorff. “The key is to consider factors like how well patients can tolerate BP medications, their overall risk for stroke, and the potential for using less rigid prescription therapies.”
In theory, the relationship between diastolic BP and coronary events should show a J-shaped curve, according to Dr. Rosendorff. Unfortunately, there are no data on the diastolic BP levels that correspond to the lower limit of autoregulation in coronary circulation, in healthy individuals, or in patients with hypertension and CAD.
The scientific statement notes that it would be reasonable to assume that rapidly reducing diastolic BP to very low levels may be more harmful to patients with combined hypertension and CAD, but there is currently no experimental or clinical trial evidence that supports this idea. As such, clinicians must rely on clinical studies with surrogate end points and the few relevant trials that have outcomes data to attempt to resolve this issue.
According to the scientific statement writing group, most patients with CAD can achieve lower BP levels safely. The vast majority of patients will not experience problems when standard medications are used. However, clinicians should use caution in patients with coronary artery blockages and aim to lower BP levels slowly. The statement notes that physicians should not strive to decrease the diastolic BP to less than 60 mm Hg, particularly in patients older than 60 years of age.
Specific evidence-based recommendations and contraindications are discussed in the scientific statement to guide clinicians when selecting antihypertensive medications in patients with various forms of heart disease. Most patients will benefit from taking β-blockers as monotherapy or in combination with other drug classes. Other combination therapy agents that have shown to be effective in various types of patients include ACE inhibitors, angiotensin-receptor blockers, calcium-channel blockers, aldosterone antagonists, direct renin inhibitors, thiazide diuretics, and chlorthalidone and indapamide, which are thiazide-type diuretics.
“In the spectrum of drugs that are available for the treatment of hypertension, β-blockers take center stage and are the first-line therapy in patients with established CAD because they can greatly improve outcomes,” Dr. Rosendorff says. β-blockers help slow heart rate and reduce the force of cardiac contractions, thus decreasing the heart’s consumption of oxygen. They also increase blood flow to the heart by prolonging the time between contractions.
Managing Modifiable Factors
In addition to treating hypertension, the writing group also recognizes the importance of modifying other risk factors for heart attack, stroke, and other vascular diseases, according to Dr. Rosendorff. “These include abdominal obesity, abnormal cholesterol levels, diabetes, and smoking.” It is recommended that physicians consult other recent guidelines on the assessment of cardiovascular risk, lifestyle management relating to diet and exercise, and the management of obesity and dyslipidemia when caring for hypertension in patients with established CAD.