White-coat hypertension as a cause of cardiovascular dysfunction

BACKGROUND

The increasing use of 24 h ambulatory blood pressure monitoring has allowed diagnosis of white-coat hypertension, in which blood pressures are higher on clinic measurements than on ambulatory monitoring. Treatment is not generally thought to be necessary for this disorder. However, there is evidence that patients with white-coat hypertension develop renal impairment and left ventricular hypertrophy. We undertook this study to assess whether white-coat hypertension, in the absence of cardiovascular structural abnormalities, is associated with cardiovascular functional abnormalities.

METHODS

Cardiovascular function was assessed by ultrasonography in three groups of patients classified as normotensive, persistently hypertensive, or white-coat hypertensive (23, 20, and 22 patients, respectively) on the basis of ambulatory blood pressure monitoring, carried out for 28 h with recordings taken every 15 min during the day and every 20 min during the night, and clinic measurements, made with a semi-automatic oscillometric device.

RESULTS

Similar abnormalities of diastolic left ventricular function were identified in the patients with persistent hypertension and those with white-coat hypertension; both groups differed in these indices from the normotensive group (E/A ratios 0.94 [SD 0.23], 1.06 [0.21], and 1.24 [0.31] respectively; ANOVA p < 0.005). In addition, the white-coat and persistently hypertensive groups, when compared with the normotensive group, showed similar abnormalities of elasticity, compliance, and stiffness (stiffness index 4.32 [1.90], 4.53 [1.38], and 3.27 [0.95] respectively; ANOVA p < 0.05) of the large arteries.

INTERPRETATION

Functional cardiovascular abnormalities were identified in white-coat hypertensive patients who had no identifiable structural abnormalities. Such functional abnormalities can be reversed by antihypertensive treatment. We propose that patients with white-coat hypertension might benefit from antihypertensive treatment as well as those with persistent hypertension. This hypothesis should be addressed in prospective clinical trials.

White-coat hypertension as a cause of cardiovascular dysfunction

BACKGROUND

The increasing use of 24 h ambulatory blood pressure monitoring has allowed diagnosis of white-coat hypertension, in which blood pressures are higher on clinic measurements than on ambulatory monitoring. Treatment is not generally thought to be necessary for this disorder. However, there is evidence that patients with white-coat hypertension develop renal impairment and left ventricular hypertrophy. We undertook this study to assess whether white-coat hypertension, in the absence of cardiovascular structural abnormalities, is associated with cardiovascular functional abnormalities.

METHODS

Cardiovascular function was assessed by ultrasonography in three groups of patients classified as normotensive, persistently hypertensive, or white-coat hypertensive (23, 20, and 22 patients, respectively) on the basis of ambulatory blood pressure monitoring, carried out for 28 h with recordings taken every 15 min during the day and every 20 min during the night, and clinic measurements, made with a semi-automatic oscillometric device.

RESULTS

Similar abnormalities of diastolic left ventricular function were identified in the patients with persistent hypertension and those with white-coat hypertension; both groups differed in these indices from the normotensive group (E/A ratios 0.94 [SD 0.23], 1.06 [0.21], and 1.24 [0.31] respectively; ANOVA p < 0.005). In addition, the white-coat and persistently hypertensive groups, when compared with the normotensive group, showed similar abnormalities of elasticity, compliance, and stiffness (stiffness index 4.32 [1.90], 4.53 [1.38], and 3.27 [0.95] respectively; ANOVA p < 0.05) of the large arteries.

INTERPRETATION

Functional cardiovascular abnormalities were identified in white-coat hypertensive patients who had no identifiable structural abnormalities. Such functional abnormalities can be reversed by antihypertensive treatment. We propose that patients with white-coat hypertension might benefit from antihypertensive treatment as well as those with persistent hypertension. This hypothesis should be addressed in prospective clinical trials.

Wide variation in the use of thrombolytic therapy among junior doctors in south and central Scotland

OBJECTIVES

(a) To assess the practice of junior doctors who administer thrombolytic therapy in acute myocardial infarction. (b) To assess whether wider implementation of current guidelines is indicated.

DESIGN

Postal questionnaire survey. Each questionnaire was followed by a reminder.

SETTING

Teaching and district general hospitals in Central and Southern Scotland.

SUBJECTS

Two hundred and twelve junior doctors (excluding JHO's) regularly involved in the early assessment and management of patients with acute myocardial infarction.

RESULTS

One hundred and ten questionnaires were returned (response rate 52%). There was wide inter-individual variation in clinical practice regardless of whether subjects worked in teaching or district general hospitals or as cardiologists or non-cardiologists. As many as 12% of respondents administer thrombolytic therapy in the absence of ST elevation or bundle branch block on the presenting ECG. A high percentage of subjects considered diabetic retinopathy, but not a previous history of cerebrovascular disease, a contraindication to thrombolytic therapy. Only 29% and 32% respectively worked in institutions where formal policies existed for streptokinase readministration and rt-PA administration in preference to streptokinase. The administration of thrombolytic therapy in Accident and Emergency departments is not a popular strategy, and the full efficacy of rt-PA is not realised due to inappropriate use or failure to use intravenous heparin.

CONCLUSIONS

There is wide variation in clinical practice among junior doctors who administer thrombolytic therapy for acute myocardial infarction. Wider implementation and firmer current national guidelines would ensure that patients presenting with suspected acute myocardial infarction receive optimal therapy.

Measurement of capillary cholesterol as an aid to the management of hypertensive patients with hyperlipidaemia--an assessment of the Reflotron

The Reflotron dry chemistry method of capillary cholesterol measurement has been widely adopted as a rapid means of population screening. We attempted to use it to monitor changes in cholesterol in a trial of intensive dietary intervention in hyperlipidaemic hypertensives. Four hundred and eighty-nine capillary cholesterol levels measured by the Reflotron were compared with levels for venous samples obtained simultaneously and assayed by the Biochemistry Department using conventional laboratory methods. The mean difference between them was 0.3 mmol/l +/- 0.8 (SD). Approximately one-third of the variability in the difference between the two methods was explained by the variables, Reflotron machine used and time (R2 = 54%, adjusted R2 = 34%). We conclude that the Reflotron is not suitable for accurate assessment of the modest changes in cholesterol which occur in individual patients during dietary intervention.

A comparison of the management of hypertensive patients by nurse practitioners compared with conventional hospital care

Patients with hypertension (n = 198) managed by a nurse practitioner hypertension clinic (NPC) were compared over a four-year period with an age-sex matched group of patients attending conventional hospital hypertension outpatient clinics (CHC) for follow-up in two other hospitals in the same city. Mortality is reported for an additional two years from initial presentation. There was no difference between the groups for initial supine systolic or diastolic blood pressure, weight, obesity index, alcohol use, cholesterol or glucose. The reported causes of hypertension were similar. There were more smokers initially in the CHC (46% vs. 37%). Initial drug treatment was less varied in the NPC. At the end of one year there was no significant weight loss in either group, and drug treatment was broadly similar between the two groups. Those attending the NPC, however, had a greater decrease in both supine systolic blood pressure (P less than 0.05) and diastolic blood pressure (P less than 0.01). At the end of four years there were 136 patients (69%) attending the NPC and 70 (35%) remaining in the CHC. For those remaining systolic blood pressure control was similar. Diastolic blood pressures were lower in the NPC (P less than 0.001). Mortality was not significantly different between the groups over a six-year period. This study shows that a nurse practitioner clinic can control blood pressure in a greater proportion of patients, maintain contact with more efficient follow-up of a greater percentage of patients and collect the information needed to assess the effectiveness of care over the long term.

Treatment of high blood pressure--the effect on coronary morbidity and mortality

Established drugs used in the treatment of hypertension have reduced stroke but have had disappointingly little impact on coronary artery disease and its complications. This could be due to inadequate falls in blood pressure (or excessive falls). It is possible that the role of blood pressure in ischaemic heart disease has been over-estimated compared to other risk factors. Alternatively, the drugs used previously may have adversely affected other factors. Mortality in treated hypertensives remains higher than normotensives but so does their blood pressure. The blood pressure on treatment is a much better predictor of outcome than initial blood pressure. This suggests that improved blood pressure control may be desirable. In our hospital-based hypertension clinic many patients have more than one risk factor. In spite of intensive efforts between 1980 and 1988, smoking habits changed little and serum cholesterol and random blood glucose actually rose. Cholesterol is high in our population of hypertensive patients and the mean (+/- SD) rose from 6.4 +/- 1.3 to 6.6 +/- 1.3 (n = 127; P less than 0.01). These observations highlight the importance of a multiple risk factor approach. The benefits of alternative drugs which can lower total cholesterol and/or low-density lipoprotein (LDL) and/or raise high-density lipoprotein (HDL) deserve study in this population. A final possibility is that the widely observed association between hypertension and ischaemic heart disease is not causal (or is weak compared to other risk factors). If a common underlying mechanism caused both atheroma and hypertension then reduction of blood pressure would not be expected to reverse atheroma and its complications. At present this possibility cannot be excluded.

Hypercholesterolaemia in treated hypertensives: a controlled trial of intensive dietary advice

We evaluated dietary counselling by dietitians in hypercholesterolaemic hypertensives over 6 months. A total of 141 patients were randomly assigned to intensive advice or usual care. Body weight fell significantly in the intervention group, but did not in the controls. There was a modest but significant fall in total cholesterol from 7.1 to 6.8 and 7.1 to 6.9 mmol/l in the diet and the control groups, respectively (4 and 3%). A similar pattern emerged from the triglyceride measurements. Low-density lipoprotein fell in both groups, but only achieved significance (P less than 0.05) in the intervention group. High-density lipoprotein did not change. There was a more marked change in cholesterol when serum levels during the study were compared with the previous annual review. These falls occurred after selection for the study but before random allocation to groups. They are unlikely to reflect regression to the mean as the lipids were stable for 2 or more years before the study, but may reflect spontaneous changes in diet after the patients were labelled hypercholesterolaemic. Dietary advice can lower total cholesterol but the magnitude of this decrease is small. Additional approaches are likely to be required to reduce plasma cholesterol to a normal range.

Risk factor modification in hypertension--success and failure

A group of 175 patients have attended for four years a microcomputer based, nurse practitioner managed clinic for the long term care of hypertension. Improvement in blood pressure (BP) control was seen initially and has been maintained. Drug treatment has been with a beta blocker followed if necessary by a diuretic and/or a vasodilator. Despite individual dietary and 'stop smoking' advice, there was no marked change in body weight while only males reduced smoking. A significant increase in non fasting serum cholesterol (6.4 +/- 1.3 to 6.6 +/- 1.3 mmol/l) and glucose (5.5 +/- to 6.1 +/- 2.5 mmol/l) was seen overall, but was restricted to those patients taking a thiazide diuretic (with or without other drugs). These findings indicate the need for a more systematic collection of information on effects of long term treatment and for the development of better strategies for improving lifestyle.

Preliminary experience with a hospital blood pressure follow up clinic with nurse practitioner assessment and microprocessor based data retrieval

Experience over two years with 376 hypertensive patients managed at a clinic where the primary observations are made by a trained nurse, clinical information is held on a microprocessor, and treatment follows a standard stepped care approach has been assessed. Blood pressure control after both one and two years was appreciably improved, with over 70% of patients having diastolic pressure below 90 mm Hg compared with 22% of patients when they first attended the new clinic. The non-attendance rate was half that of the conventional hospital outpatient clinic. A computer based record system with a nurse run hypertension clinic is acceptable to patients and offers the possibility of more effective long term control of blood pressure in large numbers of patients.