Initial therapy for mild hypertension

Reducing the risk for coronary heart disease and stroke in hypertensives--comments on mechanisms for coronary protection and quality of life

The four most popular classes of antihypertensive drugs may all be considered suitable choices when initiating treatment for hypertension. The practitioner must decide which agent is appropriate for each individual patient. The main goal of treatment should be to prevent coronary events and stroke, while preserving quality of life. A 40% reduction in stroke can probably be achieved with any antihypertensive treatment, a reduction in coronary events is much harder to achieve. Available evidence from studies in men, summarized in this review, indicates that beta-blockade is superior to thiazide diuretics for the prevention of coronary events. Clinical trials have not yet produced long-term prognostic data on the effects of ACE-inhibitors or calcium antagonists on coronary events in hypertensive patients. A recent review on calcium antagonists in post-MI patients concluded that the results were disappointing, as pooled data actually showed a trend towards increased mortality with calcium antagonists as compared with placebo. Because of the large number of hypertensive patients at increased risk for coronary events in the community, the difference observed in coronary events between beta-blockade and other first-line drugs in hypertension (24%) may have important implications for clinical practice. This overall conclusion, however, has to be accepted with some reservations in view of the following observations. Firstly, no reduction in sudden death has been observed with the hydrophilic beta-blockers. Secondly, no reduction in coronary mortality in the smoking subgroup has been observed with the non-selective beta-blockers. Thus, it seems that the prevention of coronary events is more likely to be observed in patients given beta-blockers with certain pharmacological characteristics: relative lipophilicity, which enables passage of the beta-blocker through the blood-brain barrier to exert effects on pertinent central nervous beta 1-receptors. This is potentially useful in reducing the risk of sudden death. The addition of beta 1-selectivity is important for the risk reduction in smokers. Cardioselectivity is also an advantage in relation to side-effects and quality of life. The reduced risk for coronary events with certain beta-blockers is probably independent of the reduction in blood pressure: possible mechanisms studied are cardiac anti-ischaemic effects, antifibrillatory effects, antiatherosclerotic and anti-thrombotic effects.

Metoprolol versus thiazide diuretics in hypertension. Morbidity results from the MAPHY Study

The present study in hypertensive men (40-64 years old) with untreated diastolic blood pressure above 100 mm Hg was aimed at investigating whether metoprolol (n = 1,609) given as initial treatment would lower the risk for coronary events (sudden death and myocardial infarction) more effectively than thiazide diuretics (n = 1,625). A substantial part of this study was the metoprolol arm of the Heart Attack Primary Prevention in Hypertension (HAPPHY) study. The HAPPHY study was a pooling of the effect of different beta-blockers, mainly metoprolol and atenolol, in which no favorable effect in relative risk was observed for atenolol as compared with diuretics. In the present study, 255 patients suffered definite coronary events during follow-up; 25% of these events were fatal, 39% were acute myocardial infarctions, and 36% were silent myocardial infarctions. The risk for coronary events was significantly lower in patients on metoprolol than in patients on diuretics (111 versus 144 cases, p = 0.001, corresponding to 14.3 versus 18.8 cases/1,000 patient years and a relative risk of 0.76 at the end of the trial; 95% confidence interval 0.58-0.98). This difference in risk has potentially important implications for clinical practice because of the large number of hypertensive patients who are at increased risk for coronary events. Because a placebo group, for ethical reasons, could not be included, relative risk can only be expressed in relation to diuretics. There was no difference between the two treatment groups in baseline characteristics, blood pressure during follow-up, or stroke rates. Thus, the difference in risk for coronary events is probably mediated via mechanisms other than blood pressure control. However, present data might suggest that different beta-blockers may have different efficacy in preventing coronary events. The reasons for this possibility are as yet unknown.

Decreased coronary heart disease in hypertensive smokers. Mortality results from the MAPHY study

The present primary prevention study aimed at investigating whether metoprolol given as initial antihypertensive treatment would lower cardiovascular complications of high blood pressure to a greater extent than thiazide diuretics. Patients were randomized to metoprolol (n = 1,609, 8,110 patient-years) or a thiazide diuretic (n = 1,625, 8,070 patient-years). At randomization, 535 patients in the metoprolol group and 524 patients in the diuretic group were classified as smokers. Blood pressure control during follow-up was equally effective regardless of smoking habits at randomization. Cardiovascular and coronary heart disease mortality was three to four times higher in smokers than in nonsmokers, underlining the importance of smoking as a risk factor. Total and cardiovascular mortality were significantly lower for the metoprolol group than for the thiazide diuretic group in the whole study population (p = 0.028 and p = 0.012), as well as in smokers (p = 0.013 and p = 0.016). Coronary heart disease mortality was significantly lower for patients on metoprolol than for patients on diuretics in the whole study population (p = 0.048) as well as in smokers (p = 0.021). The results suggest that initial antihypertensive therapy with metoprolol is associated with a lesser incidence of total, cardiovascular, and coronary heart disease mortality as compared with initial diuretic treatment, both in the whole study population and in smokers. The favorable effect of metoprolol must be mediated via mechanisms other than the blood pressure-lowering effect of metoprolol because equal blood pressure control was achieved with both types of medication, irrespective of smoking habits at randomization.

Primary prevention in patients with hypertension: comments on the clinical implications of the MAPHY Study. Metoprolol Atherosclerosis Prevention in Hypertensives Study

The MAPHY Study was conducted to investigate whether metoprolol, a relatively beta 1-selective beta-blocker, given as initial antihypertensive treatment, would lower cardiovascular complications of high blood pressure to a greater extent than do thiazide diuretics as initial treatment at similar blood pressure control. In a controlled, randomized, stratified primary prevention study (n = 3234; 16,180 patient-years) in white men (40 to 64 years old) with mild to moderate uncomplicated hypertension, a treatment schedule starting antihypertensive treatment with metoprolol was compared with treatment starting with a thiazide diuretic. The two treatment groups were well matched in blood pressure and other major clinical characteristics at randomization, as well as at the last follow-up during treatment. Total mortality was significantly lower in patients randomized to metoprolol. At the median follow-up time (4.2 years) 28 deaths occurred in the metoprolol group and 54 in the diuretic group--a difference of 48% in total mortality (95% confidence limit, ranging from 68% to 17%), mainly because of a highly significant reduction in coronary heart disease at this point in time. The benefit demonstrated with metoprolol seems to have important implications for clinical practice and public health policy, since hypertension and coronary heart disease are major health problems worldwide.

New concepts in the treatment of elderly hypertensive patients

Present evidence from several secondary and primary prevention trials indicates that if antihypertensive treatment is initiated with a cardioselective beta-blocker such as metoprolol, a better preventive effect on total mortality, cardiovascular mortality, and atherosclerotic complications can be expected than if diuretics are used as initial therapy. Results from a large-scale, multicenter international study have shown that a regimen in which antihypertensive treatment is initiated with metoprolol once daily is effective, safe, and well tolerated in elderly hypertensive patients. This might be of particular importance since a steep increase in cardiovascular mortality and other atherosclerotic complications is seen with age. In many elderly hypertensive patients, symptoms of heart failure might be caused by poor filling in stiff hearts rather than ineffective systolic contractions. By reducing heart rate with use of a cardioselective beta-blocker, diastole will be prolonged; this will improve filling and hence stroke volume and will increase coronary flow. Long-term treatment with metoprolol has also been found to reduce left ventricular systolic wall stress, reverse hypertrophy, improve left ventricular compliance, decrease the stiffness of large arteries, reduce total peripheral resistance, and reduce albuminuria. The improvement in the stiffness of the large arteries might be of particular clinical importance in elderly patients who have isolated systolic hypertension.