Influence of isolated diastolic hypertension identified by ambulatory blood pressure on target organ damage.

Clinical decisions and controlled studies in regard to hypertension have long emphasized the casual diastolic blood pressure (DBP). The influence of superimposition of high systolic blood pressure (SBP) on the target organ damage has been less studied. To assess the role of isolated diastolic hypertension without interference of superimposition of systolic hypertension, 171 subjects with normal blood pressure, isolated diastolic hypertension (SBP < 140 and DBP > or = 90 mmHg) isolated systolic hypertension (SBP > or = 140 and DBP < 90 mmHg) or combined hypertension (SBP > or = 140 and DBP > or = 90 mmHg) determined by mean 24-h ambulatory blood pressure were compared in relation to target organ damage including ECG abnormality related to hypertension, cardiac enlargement by chest X-ray, proteinuria and retinopathy. The incidence of target organ damage was lower in subjects with normal BP than in the other three groups. The incidence of target organ damage was almost significantly higher in patients with isolated systolic hypertension than in those with isolated diastolic hypertension. No significant difference in the incidence of complications existed between patients with isolated systolic and combined hypertension. These findings demonstrate that the severity of hypertensive complications is more closely related to mean ambulatory SBP than mean ambulatory DBP. The level of systolic BP is important for predicting the severity of target organ damage in patients with high diastolic BP, because there is a significant difference in the incidence of target organ damage between isolated diastolic hypertension and combined hypertension.