Lowering blood pressure

Relationship between blood pressure and cardiac events in patients with a healed myocardial infarction

This study investigated the association between blood pressure (diastolic [DBP] and systolic [SBP]) and cardiac events in a total of 6,602 patients with a healed myocardial infarction (MI) (5,320 men, 1,282 women; mean age, 58.9+/-10.4 years), including in-patients and out-patients, from January 1986 to January 1999. The primary endpoints (cardiac events) were recurrent MI (fatal and non-fatal), death from congestive heart failure, or sudden death. The total number of cardiac events was 195 (3.0%) and the incidences of the 3 cardiac events were compared among the 3 DBP groups (DBP low group, <70 mmHg; DBP middle group, 70-89 mmHg; DBP high group, > or =90 mmHg). There were some significant differences in the characteristics of patients among the 3 groups, but no significant difference in cardiac death and total mortality was found among the 3 groups. Cardiac events occurred in 59 of 1,780 patients (3.3%, 33.9/1,000 person years) in the DBP low group, tended to be reduced in number in the DBP middle group (87 of 3,549 patients 2.5%, 21.4/1,000 person years) and were slightly increased in number in the DBP high group (24 of 642 patients 3.7%, 35.2/1,000 person years). Although this correlation between BP and cardiac events appears to be J-shaped, because there is no statistically significant difference in the rate of cardiac events among the 3 groups, we conclude that DBP does not influence the occurrence of cardiac events. The prevalence of cardiac events tended to be greater with a SBP less than 120 mmHg.

Progression of diabetic nephropathy. A focus on arterial pressure level and methods of reduction

It is well accepted that a reduction of arterial pressure to levels of less than 140/90 mmHg will slow the decline in renal function among patients with diabetic nephropathy. More recently it is appreciated that the reduction of arterial pressure to levels much below 130/85 mmHg provides even greater levels of protection against the progression of renal disease. Given that the achievement of blood pressure reduction to such a level requires more than one medication and that the patient's compliance is best with a once-daily medication, it makes sense to combine antihypertensive medications so as to maximize the benefit. In this way, fixed dose combination medications yield synergistic effects on blood pressure reduction while providing, in some cases, maximal benefit to preservation of renal function. Such a combination is the verapamil/trandolapril combination. This paper discusses in great detail the advantages of blood pressure reduction and the types of medications that may achieve both protection against diabetic nephropathy progression as well as blood pressure reduction.

Optimal blood pressure control in treated hypertensive patients. Report from the Department of Health Hypertension Care Computing Project (DHCCP)

BACKGROUND

We wished to determine the range of treated systolic (SBP) and diastolic blood pressure (DBP) associated with the best survival in hypertensive patients.

METHODS AND RESULTS

We conducted a cohort study of patients enrolled in the DoH Hypertension Care Computer Project. Five specialist hypertension clinics (95% of patients) and general practitioners (5%) followed 6214 patients (3070 men and 3144 women) with an average age of 52 years for a mean of 107 months. Total, cardiovascular, ischemic heart disease, (IHD) and stroke mortality were the outcome measures. Age-adjusted relative hazard rates were calculated giving the effect on mortality of systolic or diastolic pressure being higher by 1 mm Hg. In men the optimal level of SBP for all four measures of mortality was the lowest pressure range observed, 92 to 133 mm Hg (median 127). For women the treated SBP range of 96 to 148 mm Hg (median 137) was associated with a low total mortality and also with low to moderate rates for IHD and stroke mortality. Relative hazard rates (P < .001) for IHD mortality were 1.010 for men and 1.013 for women and for stroke mortality were 1.018 and 1.021, respectively. The results were similar in men under and over the age of 60. SBP and DBP tended to be more important in younger than older women. For treated DBP in men, a pressure of 55 to 94 mm Hg (median 87) was associated with a low total mortality. The lowest stroke mortality in men was observed for a DBP range of 55 to 83 mm Hg (median 80) but with a tendency for an increase in IHD mortality. For women DBP < 95 mm Hg (range 55 to 94, median 87) also was associated with a low total mortality. IHD mortality in women was not closely related to treated DBP, relative hazard rate = 1.003, [95% confidence index (CI); 0.990,1.017] but the relative hazard rate for men was 1.011, (95% CI; 1.000, 1.022). The relative hazard rates for treated DBP and stroke were high at 1.035 and 1.028 for men and women, respectively (P < .001). IHD mortality increased in the one third of patients with the greatest fall in DBP on treatment, provided they were not initially in the one-third group with highest untreated DBP.

CONCLUSIONS

The best overall survival was associated with a treated SBP of < 134 mm Hg in men and < 149 mm Hg in women and a treated DBP of < 95 mm Hg.

The J-curve phenomenon in stroke recurrence

BACKGROUND AND PURPOSE

The relation of poststroke blood pressure to stroke recurrence remains undetermined, and the optimal control of blood pressure has not been established. We performed the present study to resolve these issues.

METHODS

We analyzed 368 stroke patients with a history of hypertension (mean age, 62 years) who were admitted within 3 months after stroke onset and observed for 6 months or more. We determined stroke recurrence rate in relation to baseline (or initial) blood pressure, mean values of poststroke blood pressure, stroke subtypes, age, antihypertensive treatment, and other clinical features.

RESULTS

The recurrence rate had a J-curve relation to poststroke diastolic blood pressure but not to poststroke systolic blood pressure and baseline diastolic and systolic blood pressures. The stroke recurrence rate was 3.8% per patient-year in 94 patients who had a poststroke diastolic blood pressure of 80 to 84 mm Hg, significantly lower than the rates of 9.2% per patient-year (P < .05) and 11.4% per patient-year (P < .01) in those with a lower and higher poststroke diastolic blood pressure, respectively. The range of poststroke diastolic blood pressure accompanying the lowest stroke recurrence rate was higher in patients with atherothrombotic (85 to 89 mm Hg) than in those with lacunar infarction (80 to 84 mm Hg). Neither antihypertensive therapy nor patients' age affected this phenomenon.

CONCLUSIONS

The present study suggests that lower blood pressure does not always result in favorable effects on stroke recurrence. The effects of poststroke blood pressure and antihypertensive therapy on stroke recurrence may be complicated by the J-curve phenomenon.

[Identification of overtreated hypertension with statistical analysis of 100 consecutive ambulatory blood pressure monitoring]

The data obtained from 100 consecutive ambulatory blood pressure (BP) recordings performed in treated hypertensive patients (60 men, 40 women, mean age 52 +/- 14 years) were analysed to make a choice between several possible definitions of overtreatment and to evaluate the prevalence of patients thus defined as overtreated. Recordings were studied over two periods: diurnal from 9 a.m. to 7 p.m. (100 patients, 37 +/- 5 measurements/patient), and nocturnal from 11 p.m. to 7 a.m. (98 patients, 19 +/- 2 measurements/patient). The patients were first classified on the basis of reference ambulatory BP values according to sex and age. Subnormal levels were found in 25 patients for diurnal SBP, 25 for nocturnal SBP, 13 for diurnal DBP and 33 for nocturnal DBP. Several criteria of overtreatment were then tested, based on the percentile method and on the number of subnormal values: the median DBP was below the 30th reference percentile in 16 patients, and the percentage of subnormal DBP values was above 80% in 18 patients. Clinically, there was little to differentiate these patients from the rest of the population treated. The goal of treatment which, in terms of BP values, is to normalize the ambulatory BP was therefore overshot in 1 out of 5 or 6 patients depending on the criteria adopted. The significance and consequences of overtreatment cannot yet be evaluated.

Coronary flow reserve and the J curve relation between diastolic blood pressure and myocardial infarction

The results of several large studies of hypertension and follow up studies on insured people have indicated that the lower the blood pressure the better for longevity. These studies excluded subjects with overt ischaemia. More recently long term studies of hypertension that included patients with more severe forms of hypertension and did not exclude those with overt ischaemia have shown a J shaped relation between diastolic blood pressure during treatment and myocardial infarction; the lowest point (the J point) was at a diastolic blood pressure (phase V) between 85 and 90 mm Hg. The J curve seems to be independent of treatment, pulse pressure, and the degree of fall in diastolic blood pressure and is unlikely to be caused by poor left ventricular function. The most probable explanation is that subjects who have severe stenosis of the coronary artery as well as hypertension have a poor coronary flow reserve, which makes the myocardium vulnerable to coronary perfusion pressures that are tolerated by patients without ischaemia, particularly at high heart rates. An optimal diastolic blood pressure (phase V) for such patients is about 85 mm Hg, though particular caution is appropriate when treating very old patients (84 and over) and patients aged 60-79 who have isolated systolic hypertension.