According to new recommendations, patients once considered to be “prehypertensive” now require more than just lifestyle modification.
The American Heart Association has issued, for the first time, guidelines that focus specifically on the treatment of hypertension in the prevention and management of ischemic heart disease. The Scientific Statement addresses in detail the needs of high-risk individuals as well as those with angina and other indications of atherosclerotic disease, MI, and ischemia-related heart failure (HF).
The new recommendations have “enormous implications for primary-care clinicians,” says Clive Rosendorff, MD, professor of medicine in the Division of Cardiology at Mount Sinai Medical Center, in New York City, and chair of the committee that wrote the guidelines. Changes in two areas in particular—BP goals and certain recommended medications—reflect research of recent years and are highly relevant for patients in primary care.
Treatment goals—a downward shift
“The currently accepted goal for hypertension control, enshrined in the JNC-7 [The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure] recommendations published in 2003, is for BP <140/90 mm Hg, except in cases of diabetes and chronic kidney failure, where the target is <130/80,” Dr. Rosendorff says. “What this Scientific Statement has done is to add a whole new cohort of patients to the <130/80 group.”
The newcomers include all patients with established coronary heart disease (CHD) and its equivalents (such as carotid artery occlusion and peripheral arterial disease), acute MI, ischemic HF, “and perhaps most radically, all patients at high risk of CHD,” Dr. Rosendorff notes.
These additional patients, he observes, had been placed by JNC-7 within the “prehypertension” [120-139/80-89] range, for which careful monitoring and lifestyle interventions were recommended, but a more aggressive approach including medication was not.
For some patients within the groups in question, new target BPs may be even lower. In those with stable angina and left ventricular (LV) dysfunction and for those with HF, for example, “consideration should be given” to reductions to 120/80, the new guidelines say.
These treatment goals are “hedged with a number of caveats,” Dr. Rosendorff warns. In particular, clinicians are advised to proceed slowly when diastolic BP (DBP) is elevated and to exercise caution when inducing DBP <60 in patients who have diabetes mellitus or symptomatic coronary artery disease (CAD), or in those who are older than 60 years of age.
Lowering systolic BP in older patients with wide pulse pressures can bring DBP below this threshold, which “should alert the clinician to assess very carefully any untoward signs or symptoms, especially those due to myocardial ischemia,” the authors say.
Primary prevention of CAD
The guidelines distinguish between individuals at low and high risk of CAD. The latter group (for whom target BPs, as discussed previously, should be 130/80) includes those with diabetes or chronic renal disease as well as anyone with a 10-year Framingham risk score =10%.
“It is heavily biased to favor age; a high proportion of older patients [e.g., a 70-year-old with no other risk factors] would achieve this score,” Dr. Rosendorff notes.
While lifestyle modifications (including smoking cessation, weight loss, reduced sodium intake, exercise, and a healthy diet pattern) are described as “entirely appropriate” for these patients, the guidelines observe that their impact is generally modest and emphasize the need for pharmacotherapy to achieve target BPs.
BP reduction per se, rather than specifics of drug choice, is the key factor involved in CAD risk reduction, the authors state, but they mention that evidence supports ACE inhibitors and angiotensin receptor blockers (ARBs), calcium channel blockers, or thiazide diuretics as first-line agents and as components of combined treatment if monotherapy isn’t enough (Table 1).
“Notably absent from that list are beta blockers,” observes Dr. Rosendorff. “The consensus in the hypertension community is that fewer data support the use of this drug class for the primary prevention of CAD.” The apparent “disconnect” between the impact of beta blockers on brachial and central arterial pressure suggests an explanation for its relative inefficacy in this regard, he states. Moreover, the use of some beta blockers has been linked to increased diabetes prevalence.
Symptomatic CAD and stable angina
Once there is evidence of established CAD or heart failure, however, “beta blockers come in from the periphery to center stage,” Dr. Rosendorff states. “They are a keystone of treatment for those conditions.”
Beta blockers are, according to the guidelines, the antihypertensives of first choice for patients with angina because these antianginal drugs effectively alleviate anginal symptoms in addition to lowering BP. Patients who also have diabetes and/or LV dysfunction should receive an ACE inhibitor or ARB as well, with a thiazide diuretic added to the mix if there is a history of MI. The triple combination should be considered even without such a history, the authors say.
Calcium channel blockers may play a supporting role. In the absence of LV dysfunction, a nondihydropyridine calcium channel blocker, such as diltiazem or verapamil, can take the place of a beta blocker when the latter is contraindicated or causes intolerable side effects in the patient; a long-acting dihydropyridine calcium channel blocker can be added to the beta blocker-ACE inhibitor/ARB-thiazide combination if that regimen proves to be inadequate for either the angina or BP reduction.
Nitrates, antiplatelet and anticoagulant drugs, and lipid-lowering agents are by no means contraindicated in hypertensive patients, but the risk of hemorrhagic stroke lends urgency to the need to reduce severe hypertension when antiplatelet or anticoagulant drugs are being taken.
Ischemic heart failure
Ischemic heart disease is responsible for most HF. A majority of these patients are also hypertensive, and drugs for HF generally lower BP as well. The guidelines recommend a regimen that combines drugs from a number of classes: a beta blocker, ACE inhibitor or ARB, diuretic, and (in severe cases) an aldosterone receptor agonist. Each of these has been shown to have beneficial effects for both conditions, says Dr. Rosendorff.
Certain beta blockers in particular have been shown in clinical trials to improve outcome in HF patients: carvedilol, metoprolol, and bisoprolol. Nitrates may also have a role in the treatment of black patients with hypertension and advanced HF. A 2004 trial suggested that addition of hydralazine and isosorbide nitrate increased the benefit of the above regimen. (Hydralazine appears to reduce the tolerance that had heretofore limited the utility of long-term nitrates in this application.)
Some medications should be avoided because they have been associated with increased mortality or worsened HF symptoms in studies or because such risks can be reasonably inferred from the agent’s mechanism of action, the guidelines say. These include nondihydropyridine calcium channel blockers, doxazosin, and moxonidine. Clonidine, in the same class as moxonidine, should “probably” be avoided as well, and alpha blockers as a group should be used with caution and only when other agents fail to achieve adequate BP control.
In addition to pharmacotherapy, the guidelines endorse a behavioral-modification program that includes sodium restriction and a “closely monitored” exercise program for HF patients. Well-supervised training appears to reduce recurrent cardiac events in this population, the authors observe.
The American Heart Association Scientific Statement Treatment of Hypertension in the Prevention and Management of Ischemic Heart Disease appeared in Circulation (2007;115:2761-2788) and is available at: http://circ.ahajournals.org/cgi/content/full/115/21/2761 (accessed June 4, 2008).