The findings suggest that 24-hour ambulatory BP monitoring can disclose end-organ damage, potentially before it's apparent by echocardiography, and thereby perhaps add to hypertension risk stratification, according to Dr Fredrik H Nyström (University of Linköping, Sweden) and colleagues.

It was also found that carefully obtained serial BP readings in the clinic correlate significantly with 24-hour ambulatory numbers and with LV mass index. This observation was the focus of the group's report on the same population in the June 2005 issue of the Journal of Internal Medicine [2].

Together, the findings suggest that while 24-hour measurements are not necessarily better than office-based numbers at predicting left-ventricular hypertrophy (LVH), they could help identify a subgroup with potentially heightened risk, coauthor Dr Thomas Kahan (Karolinska Institute, Stockholm, Sweden), told heartwire.

If you are a nondipper, you have a more advanced stage of hypertension in terms of left ventricular mass and systolic and diastolic dysfunction.

The study's 75 hypertensive patients with LVH plus 35 hypertensives with normal ventricular dimensions—none of whom were on antihypertensive therapy—and 23 normotensive control subjects were evaluated by BP measurement at home using 24-hour ambulatory monitoring and in the clinic. Three clinic readings, each one minute apart, were obtained by nurses with patients in the sitting position.

The group found "excellent" correlations between mean in-clinic and ambulatory BP readings (p<0.0001 for both systolic and diastolic numbers) as well as significant relationships between BP in both settings and LV mass index, regardless of dipper status. However, nondippers displayed other functional and echocardiographic signs of current or impending systolic and diastolic dysfunction, including significantly reduced LVEF, higher Doppler E-wave:A-wave ratios, and shorter isovolumic relaxation times. Their levels of both brain-type and atrial natriuretic peptides, known CV risk markers, were also significantly higher.

Although hypertensives should be treated regardless of dipper status, Kahan observed, 24-hour ambulatory BP monitoring can provide more information about CV risk. "If you are a nondipper, you have a more advanced stage of hypertension in terms of left ventricular mass and systolic and diastolic dysfunction" and should be treated more intensively with BP-lowering agents. Although echocardiography and carotid-artery ultrasound are typically used for similar risk stratification, nighttime BP measurements could potentially pick up the ventricular structural changes at an earlier stage, according to Kahan.