Multiple risk functions for predicting coronary heart disease: the concept, accuracy, and application

Effects of doxazosin on serum lipids: a review of the clinical data and molecular basis for altered lipid metabolism

The goal of antihypertensive treatment must be not only the reduction of high blood pressure, but also the effective management of elevated cholesterol levels and other risk factors of coronary heart disease (CHD). In controlled clinical trials, doxazosin has been shown to have antihypertensive efficacy comparable with other classes of antihypertensive agents and to lower the levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides while increasing the levels of high-density lipoprotein cholesterol. Doxazosin appears to inhibit the development of CHD on two fronts. First, doxazosin binds to the alpha 1-adrenoreceptor and inhibits the receptor-mediated responses to epinephrine and norepinephrine. Second, doxazosin has direct and indirect effects on lipid metabolism by increasing LDL receptor activity, decreasing intracellular LDL synthesis, reducing the synthesis and secretion of very low-density lipoprotein cholesterol, and stimulating lipoprotein lipase activity. Doxazosin may also inhibit platelet aggregation. Long-term studies will determine how these actions translate into reductions in the morbidity and mortality rates of CHD. First-year results from the Treatment of Mild Hypertension Study (TOMHS) have demonstrated expected reductions in blood pressure for all antihypertensive agents studied. The lipid changes have varied with the type of antihypertensive treatment and have been favorable for doxazosin.

Hypertension in the elderly: epidemiology and pathophysiology

In all but a few remote and unacculturated tribes, blood pressure rises with advancing age. By the time Western adult males or females reach their 70s their probability of being hypertensive (BP greater than 140/90 mmHg) exceeds 50%. Unlike various other risk factors for vascular disease, hypertension retains its predictive power as age increases, but since the baseline risk is higher, the number of cases of disease attributable to hypertension is much higher in the elderly than in the young. The reason for the rise in blood pressure with aging is not well established, although a high lifetime intake of sodium may be a contributing factor. It now appears that the major hemodynamic abnormality is an increased peripheral resistance. It is possible that an accentuation of changes that take place with normal aging might be responsible for this phenomenon. They include a reduction in renal function, decreased baroreceptor sensitivity, or increased sympathetic activity. Up until the present time studies have been unable to isolate the mechanisms involved.

Evaluation of the associations between carotid artery atherosclerosis and coronary artery stenosis. A case-control study

To evaluate the consistency, strength, and independence of the relation of carotid atherosclerosis to coronary atherosclerosis, we quantified coronary artery disease risk factors and extent of carotid atherosclerosis (B-mode score) in 343 coronary artery disease patients and 167 disease-free control patients. In univariable analyses, there was a strong association between coronary status and extent of carotid artery disease in men and women older than and younger than 50 years (p less than 0.001 for men and women greater than 50 years, p less than 0.001 for women less than or equal to 50 years, p = 0.045 for men less than or equal to 50). The relation remained strong after control for age in men and women older than 50 years and in women younger than 50 (p less than 0.001 for men and women greater than 50 years, p = 0.003 for women less than or equal to 50) but did not persist after control for age in men younger than 50. Logistic models that included coronary disease risk factors, with or without B-mode score, as independent variables and presence or absence of coronary disease as the outcome variable indicated that the extent of carotid atherosclerosis was a strong, statistically significant independent variable in models for men and women older than 50 years of age. Next, we examined the usefulness of B-mode score as an aid in screening for coronary artery disease in men and women older than 50 years. Classification rules, both including and excluding B-mode score, were developed based on logistic regression and, for comparison, recursive partitioning (decision trees). The performance of these rules and the bias of their performance statistics were estimated. The improved classification of the study sample when B-mode score was incorporated in the rule was statistically significant only for men (p = 0.015). However, the addition of B-mode score was found to 1) increase the median discrimination score for both sex groups based on the logistic model, and 2) yield better sensitivities and specificities for rules based on recursive partitioning. Thus B-mode score is strongly, consistently, and independently associated with coronary artery disease in patients older than 50 and is at least as useful as well-known risk factors for identifying patients with coronary artery disease.

Initial drug therapy for hypertensive patients with hyperlipidemia

Hypertension and hyperlipidemia are cardiovascular risk factors that commonly coexist. Studies have indicated that it is important to control both risk factors to achieve significant reductions in morbidity and mortality. Recent debate has focused upon whether traditional step I antihypertensive agents can substantially lower these risks because of their effects on plasma lipids. This debate continues to be unresolved. However, for the patient with elevated lipid levels, diuretics and beta-blockers may make the management of the lipid disorder more difficult. Therefore it may be desirable to select alternative step I antihypertensive agents that will not interfere with the therapy for hyperlipidemia. Alternative step I agents include alpha 1-blockers, ACE inhibitors, and calcium channel blockers. These agents either have no effect on plasma lipids or they improve the lipid profile. Generally, these drugs are well tolerated and provide good alternatives for patients with hyperlipidemias. The initial drug of choice can be chosen depending upon other patient variables such as age, race, or concomitant diseases.

Review of the effects of doxazosin, a new selective alpha 1-adrenergic inhibitor, on lipoproteins in patients with essential hypertension

Control of high blood pressure has failed to reduce the risk of atherosclerotic coronary heart disease (CHD). Hypercholesterolemia, which is common among hypertensive patients, cigarette smoking, and hypertension are the major risk factors for CHD. To minimize CHD risk, elevated blood pressure and atherogenic lipid levels should be lowered, but various antihypertensive agents appear to adversely affect lipid levels, actually precluding the CHD risk reduction expected from blood pressure control. Doxazosin, a once-daily, long-acting, alpha 1-adrenergic inhibitor, not only is effective therapy for essential hypertension but also has a favorable impact on lipids. During controlled studies of doxazosin's antihypertensive efficacy, the following blood lipid levels were measured: total cholesterol, total triglycerides, high-density lipoprotein (HDL) cholesterol (including HDL2 and HDL3), low-density lipoprotein (LDL) cholesterol, very low-density lipoprotein cholesterol, and apoproteins (apos) AI and B. Results showed total cholesterol (-0.8 to -8.9 percent), total triglycerides (-5.0 to -17.4 percent), and LDL (-9.0 to -16.9 percent) were reduced. The positive prognostic indicators, HDL (+0.7 to +13.0 percent) and HDL:total cholesterol ratio (+3.1 to +26.3 percent), were increased. Apo B decreased, but apo AI remained unchanged. In these hypertension studies, doxazosin has favorably reduced two major CHD risk factors. As part of a new, long-term, controlled, multicenter trial, the prospective benefits of these risk factor reductions on CHD morbidity and mortality will be quantified for doxazosin and other antihypertensive agents.

Usefulness of thallium-201 scintigraphy in predicting the development of angina pectoris in hypertensive patients with left ventricular hypertrophy

Hypertension and left ventricular (LV) hypertrophy are independent risk factors for the development of coronary artery disease. To determine whether patients at higher risk for coronary artery disease can be identified, 40 asymptomatic hypertensive men with LV hypertrophy were prospectively studied using exercise thallium-201 scintigraphy and exercise radionuclide angiography. Endpoints indicative of coronary artery disease were defined as the subsequent development of typical angina pectoris, which occurred in 8 patients during a median follow-up of 38 months, or myocardial infarction, which did not occur. The exercise electrocardiogram was interpreted by standard ST-segment criteria and by a computerized treadmill exercise score. Abnormal ST-segment responses were present in 16 of the 40 hypertensives (40%), whereas the treadmill score was positive in 8 of those same 40 patients (20%). Scintigraphic perfusion defects assessed both visually and semiquantitatively were observed in 8 of 40 (20%) patients. An abnormal ejection fraction response to exercise was present in 40% (16 of 40) of patients, and 3 of 40 (7.5%) developed new wall motion abnormalities during exercise. Six of 8 patients with either perfusion defects or abnormal treadmill score developed typical angina during follow-up. All 5 patients with concordant positive exercise scintigrams and treadmill score developed chest pain during follow-up and had coronary artery disease confirmed by coronary angiography. However, only 7 of 16 (44%) patients with positive ST changes or abnormal ejection fraction responses during exercise developed chest pain during follow-up. In contrast, of 32 patients with negative scintigrams only 2 developed atypical chest pain syndromes, and significant coronary artery disease was excluded by angiography in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors associated with high density lipoprotein cholesterol in a population with high high density lipoprotein cholesterol levels

A cross-sectional study of a random sample of 976 coloureds (mixed race) of the Cape Peninsula, ages 15 to 64 years old, revealed a population with unexpectedly high levels of high density lipoprotein (HDL) cholesterol. The mean level for men was 55.4 +/- 16.1 mg/dl (SD) and for women, 60.8 +/- 16.0 mg/dl. The ratio of HDL cholesterol to total cholesterol expressed as a percentage was 26.3% +/- 9.5% for men and 28.1% +/- 9.3% for women. The HDL cholesterol levels were apparently lower than those of black and Negro populations, yet higher than those of Caucasian populations. Men with levels of HDL cholesterol above the median reported a personal history and a family history of coronary heart disease less frequently than did men with lower levels, while women with high levels of HDL cholesterol were less likely to have a history of hypertension or diabetes. Stepwise multiple regression analysis of variables significantly associated with HDL cholesterol levels showed that they explained 29.7% and 24.7%, respectively, of the variation in HDL cholesterol in men and women. Those variables independently associated with HDL cholesterol in both men and women were: serum triglyceride (-), cigarette consumption (-), alcohol, body mass index (-), age, and serum low density lipoprotein cholesterol levels (-). The reasons for the relatively high HDL cholesterol levels in this population are unknown. However, it would seem possible that these levels offer some protection against the high risk factors of smoking, hypertension, and hypercholesterolemia.

Risk factors for coronary artery disease in healthy persons with hyperinsulinemia and normal glucose tolerance

We studied the relation of serum insulin levels to plasma lipid levels and blood pressure in two groups drawn from among 247 healthy, normotensive nonobese subjects with normal glucose tolerance. One group of 32 subjects was defined as having hyperinsulinemia (serum insulin, greater than 2 SD above the mean) and then compared with 32 normoinsulinemic subjects (serum insulin within 1 SD of the mean) matched for age (mean, 39 years), sex (22 men and 10 women), and body-mass index (24.7). The two groups had similar patterns of smoking, drinking, and physical exercise. Plasma glucose levels after an oral glucose challenge were significantly higher (P less than 0.05) in the hyperinsulinemic group. In addition, the mean (+/- SEM) fasting plasma triglyceride levels in subjects with hyperinsulinemia were significantly higher (1.73 +/- 0.2 vs. 1.24 +/- 0.1 mmol per liter) and the plasma high-density lipoprotein cholesterol concentrations were lower (1.21 +/- 0.06 vs. 1.43 +/- 0.06 mmol per liter) than in subjects with normoinsulinemia. Both systolic (126 vs. 119 mm Hg; P less than 0.05) and diastolic (85 vs. 78 mm Hg; P less than 0.01) blood pressures were significantly elevated in the group with hyperinsulinemia. We conclude that healthy persons with hyperinsulinemia and normal glucose tolerance have an increase in risk factors for coronary artery disease, as compared with a well-matched group of healthy subjects with normal insulin levels.

Job characteristics in relation to the prevalence of myocardial infarction in the US Health Examination Survey (HES) and the Health and Nutrition Examination Survey (HANES)

Associations between psychosocial job characteristics and past myocardial infarction (MI) prevalence for employed males were tested with the Health Examination Survey (HES) 1960-61, N = 2,409, and the Health and Nutrition Examination Survey (HANES) 1971-75, N = 2,424. A new estimation method is used which imputes to census occupation codes, job characteristic information from national surveys of job characteristics (US Department of Labor, Quality of Employment Surveys). Controlling for age, we find that employed males with jobs which are simultaneously low in decision latitude and high in psychological work load (a multiplicative product term isolating 20 per cent of the population) have a higher prevalence of myocardial infarction in both data bases. In a logistic regression analysis, using job measures adjusted for demographic factors and controlling for age, race, education, systolic blood pressure, serum cholesterol, smoking (HANES only), and physical exertion, we find a low decision latitude/high psychological demand multiplicative product term associated with MI in both data bases. Additional multiple logistic regressions show that low decision latitude is associated with increased prevalence of MI in both the HES and the HANES. Psychological workload and physical exertion are significant only in the HANES.

A biopsychosocial model of medical student distress

Medical student distress was examined in two consecutive first-year classes (N = 312) in September, before they interacted with the school regimen, and again in May before exams. Anxiety means were one SD above the normative mean for nonpatients at both times. The number of students reporting a significant level of depression doubled from September (N = 36) to May (N = 78). The correlation of distress in September and May was .40, indicating that for many students distress was enduring. A biopsychosocial model of initial distress explained more variance (36%) in the cross-validation sample than did any one variable alone. Distressed students had higher Type A scores. Also, anger held in was a risk factor for distress in students with a family history of cardiovascular disease (CVD). Students who hold anger in may experience prolonged stress which, coupled with a family history of CVD, could make them psychobiologically vulnerable to distress.

Systemic hypertension, left ventricular hypertrophy and coronary artery disease

The potential mechanisms for the development of myocardial ischemia in hypertensive left ventricular (LV) hypertrophy involve changes in the coronary circulation characterized by a reduction of coronary vascular reserve and an acceleration of the atherosclerotic process. This combination of factors is probably reflected in the epidemiologic findings of increased coronary morbidity and mortality in hypertension, particularly when it is associated with LV hypertrophy. The failure of several antihypertensive trials to reduce coronary morbidity and mortality emphasizes the importance of early detection of significant coronary artery disease (CAD) among hypertensive patients with LV hypertrophy. A strategy to detect asymptomatic CAD based on combined probability of 2 noninvasive tests is discussed. Results obtained in hypertensive LV hypertrophy showed a 20% to 30% incidence of abnormal exercise test results, and these positive findings were predictive for the development of typical angina during a 3-year follow-up. Based on these results and reported data, it is extrapolated that patients with silent ischemia may contribute up to 40% of the coronary mortality observed in previous antihypertensive trials. These findings suggest the need for an early detection and separate follow-up of these patients with silent CAD, to better assess the influence of antihypertensive treatment on coronary morbidity and mortality.

How can we diagnose coronary heart disease in hypertensive patients?

Chest pain is a common complaint among hypertensive patients. Hypertension and coronary heart disease each may present with symptoms and signs that are clinically indistinguishable. Noninvasive testing by routine exercise stress testing and stress radionuclide angiography are not reliably predictive of ischemia resulting from obstructive epicardial coronary artery disease and should be abandoned for that diagnostic purpose. Noninvasive thallium-201 myocardial perfusion imaging for this purpose may prove to be a valuable tool, avoiding the risk and expense of coronary arteriography. However, carefully performed prospective studies are not available. Because of the high prevalence of both diseases, a high priority must be given to obtaining these data and evaluating other noninvasive methods (especially positron emission tomography) if they appear promising.

Plasma lipid and lipoprotein concentrations in Chinese males with coronary artery disease, with and without hypertension

Plasma lipid and lipoprotein concentrations were determined in 125 Chinese males with a medical history and electrocardiographic abnormalities consistent with the diagnosis of coronary artery disease (CAD). All subjects underwent coronary arteriography, and patients were divided into 3 groups based upon the results of the coronary arteriograms: 1) patients with a negative angiogram (CAD-, n = 30), without hypertension; 2) patients with a positive angiogram, without hypertension (CAD+, n = 70); and 3) patients with a positive angiogram, who had hypertension (CAD + HT, n = 25). Mean fasting plasma lipid and lipoprotein concentrations of these 3 groups of patients were compared to values in age and weight-matched groups of normal individuals (n = 80) and untreated patients with hypertension and no evidence of CAD (HT, n = 20). The results indicated that total plasma triglyceride, cholesterol, and LDL-cholesterol levels were significantly higher (P less than 0.001) than normal in patients with CAD+ and CAD + HT, whereas only plasma cholesterol levels were higher than normal in patients with HT. Although patients with CAD- had values intermediate between normal and CAD, the differences were not statistically significant. In addition, the ratio of LDL to HDL-cholesterol was significantly increased (P less than 0.05-0.001) above normal in patients with CAD+, CAD + HT, and HT. As before, the values in patients with CAD- were intermediate. These data document the presence of multiple abnormalities of lipid and lipoprotein concentration in patients with angiographic evidence of CAD, whether or not they were hypertensive. Furthermore, abnormalities in lipid and lipoprotein metabolism were seen in patients with hypertension alone.

Plasma lipid lowering effects of doxazosin, a new selective alpha1 adrenergic inhibitor for systemic hypertension

Hypertension and hypercholesterolemia are 2 major risk factors for atherosclerotic coronary artery disease (CAD). Elevations of both blood pressure and serum cholesterol levels should be reduced to control CAD risk. Doxazosin is a once-daily, long-acting, selective alpha 1-adrenergic inhibitor that is effective for the treatment of essential hypertension. During controlled studies of doxazosin's antihypertensive efficacy, 3 serum lipid parameters were measured; total cholesterol, total triglyceride and high density lipoprotein (HDL) cholesterol. In 10- to 12-week placebo-controlled studies, 142 doxazosin-treated patients were compared with 155 placebo-controlled subjects. Doxazosin patients had an increase of 8.9% in the HDL/total cholesterol ratio (p less than 0.05), whereas total cholesterol, HDL cholesterol and triglyceride levels were not significantly different between the 2 study groups. During a 52-week comparison of doxazosin versus atenolol, doxazosin treatment was associated with a significant decrease in total triglyceride levels (5%; p less than 0.001) and increases in HDL cholesterol levels (3.9%; p less than 0.01) and HDL/total cholesterol ratio (5.4%; p less than 0.0001). Doxazosin is an effective antihypertensive agent that has a favorable impact on serum lipid levels, thereby promoting a beneficial effect on 2 major CAD risk factors.

Comparison of effects on lipid metabolism of antihypertensive drugs with alpha- and beta-adrenergic antagonist properties

Elevated blood cholesterol levels are a major cause of coronary heart disease. High-density lipoprotein cholesterol is regarded as a protective cholesterol fraction that is negatively associated with the incidence of coronary heart disease. Thus, the ratio of high-density lipoprotein to total cholesterol levels is an expression of the total atherogenicity--the higher the ratio, the lower the risk of coronary heart disease. There is a sharp contrast between alpha- and beta-adrenergic blockers with regard to their effect on the profile of blood lipids. In most studies, alpha blockers increased high-density lipoprotein cholesterol levels and decreased serum triglyceride levels. In addition, alpha blockers generally reduce total serum cholesterol levels. On the other hand, most beta blockers reduce serum levels of high-density lipoprotein cholesterol and increase serum triglyceride levels. European clinical trials recently investigated the effects of alpha blockers and beta blockers on blood lipids in a total of 104 and 281 patients with hypertension, respectively. On the average, selective alpha blockade increased the high-density lipoprotein cholesterol:total cholesterol ratio by 11.3 percent and reduced serum triglyceride levels by 11.4 percent. In contrast, the selective and nonselective beta-adrenergic blockers atenolol, metoprolol, and propranolol reduced that ratio by 11.7 percent and increased serum triglyceride levels by 25.8 percent. This difference between alpha and beta blockers may significantly influence the risk profile of coronary heart disease and should be given strong consideration when choosing drug therapy for hypertensive patients.

The orthogonal electrocardiogram as risk indicator for the prediction of myocardial infarction and/or cardiac death

In a prospective study on Coronary Heart Disease (CHD) orthogonal electrocardiograms (Frank) were recorded annually for ten years from 1,444 asymptomatic, middle-aged males with a mean age of 57.4 +/- 10.6 years. Cases with overt or suspected CHD were excluded. The purpose of the study was to identify risk indicators in electrocardiograms and to compare them with other known risk factors used for prediction of acute CHD events such as myocardial infarction (MI) and/or cardiac death (CD). Such acute events occurred in 88 cases. Pre-event ECGs of these acute events were compared with all others without events, using logistic regression analysis. Identified ECG risk indicators were then compared with other known risk factors such as smoking, blood pressure, cholesterol, age, weight, etc. The predictive power of the ECG, derived mainly from the ST-T complex, exceeded all others by a wide margin. The amplitude of the first 1/8 of the ST-T complex in lead x (similar to V5-V6) together with relative body weight proved best when one pre-event record was available. Prediction improved when ECG changes between two pre-event recordings were included. Precision of measurements by computer appeared essential for improvements in CHD prediction.

The antihypertensive effects of doxazosin: a clinical overview

Doxazosin is a long-acting selective alpha 1-adrenoceptor antagonist which has been shown to be effective and well tolerated in the treatment of hypertension given in once-daily doses as monotherapy for up to 1 year or as an adjunct to thiazide or beta-adrenoceptor blockers. Doxazosin has a pharmacokinetic profile in both young adult and elderly subjects which is compatible with once-daily administration. This has been confirmed by measurement of steady state pharmacokinetics in patients receiving long-term doxazosin therapy. In controlled double-blind studies involving approximately 550 patients on doxazosin 1-16 mg once daily, significant reductions in both standing and supine BP were maintained throughout the 24 h dosing interval. Effectiveness of doxazosin in terms of BP lowering and proportion of responders was similar to that achieved with hydrochlorothiazide 25-100 mg once daily, atenolol 50-100 mg once daily, nadolol 40-160 mg once daily, metoprolol 100-200 mg per day given twice daily, or prazosin 1-20 mg per day given twice daily. Doxazosin was as effective in elderly patients as in the younger age group and was as effective in blacks as in caucasians. Doxazosin was well tolerated. Side-effects were generally mild to moderate in severity. Overall incidence, including postural effects early in treatment, was similar to that seen with the comparative agents. In comparison with placebo, doxazosin favourably increased (P less than 0.05) the HDL/total cholesterol ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Therapy of mild hypertension: an overview

The "push to treat" persons with mild hypertension in an effort to decrease cardiovascular risk and, ultimately, coronary mortality began even before data from clinical trials on the value of active treatment were published. Today, although active therapy has not been proved to be of value to all patients with mild hypertension, the impetus to prescribe drug therapy is even stronger. No drug is without risks; therefore, drug treatment is recommended only for those patients in whom the risk of disease--a risk that can be quantitated by careful risk assessment--outweighs the risk of therapy. This is especially important when the hazards of high-dose diuretic therapy, the first step in the widely used stepped-care approach, are considered. An alternative approach for selected patients with mild hypertension is first to prescribe 1 of the other available antihypertensive medications, such as alpha- or beta-blocking drugs along with moderation of dietary sodium. This approach is more conservative than that advocated by many authorities, but it is similar to the treatment proposed by an expert committee of the World Health Organization and the International Society of Hypertension.