What is the value of home (self) blood pressure monitoring in patients with hypertensive heart disease?
The acceptable maximal blood pressure values for patients monitoring their own blood pressure at home have not yet been determined. Risk of cardiovascular disease may be increased at lower blood pressure limits than those suggested by the World Health Organization (WHO) for clinic readings. We have investigated 25 patients with proven hypertensive small-vessel disease and compared self-monitored, ambulatory 24-h (ABPM) and clinic blood pressure measurements. The diagnosis of hypertensive small-vessel disease was based on clinical evidence of myocardial ischemia, angiographic exclusion of coronary heart disease, and abnormal single-photon emission computed tomography (SPECT) thallium-201 myocardial scintigraphy. Mean self-monitored values were 143.4 +/- 13.6/84.0 +/- 9.4 mm Hg (95% confidence intervals 137.6-149.0 mm Hg for systolic and 80.1-87.9 mm Hg for diastolic blood pressure). Both home and ambulatory daytime readings (141.2 +/- 11.8/83.9 +/- 10.2 mm Hg) were significantly lower than the clinic readings by the physicians (clinic systolic, 169.2 +/- 16.5 mg; clinic diastolic, 95.0 +/- 11.6 mm Hg; P < .0001 v home and ambulatory readings). There was no significant difference between home and ambulatory readings. Agreement between home and ambulatory values was much closer than for clinic v ABPM readings. The respective correlation coefficients for systolic values were r = 0.702 (home v ABPM; P < .0001) and r = 0.32 (clinic v ABPM; NS). For diastolic values correlation coefficients were r = 0.674 (home v ABPM; P < .0002) and r = 0.574 (clinic v ABPM; P < .003) respectively. In conclusion, the reported results suggest that the WHO suggested definition of hypertension (> or = 140/90 mm Hg) may be set too high when blood pressures are measured by the patient at home. A cutoff value of < 135/85 mm Hg, as in ABPM, may be a more realistic upper limit for self-monitoring.