Standardized stress testing in the cardiovascular laboratory: has it any bearing on ambulatory blood pressure values?

We examined 77 males (mean age 45 years; mean casual blood pressure 139/94 mmHg; no secondary hypertension) to evaluate the relationship between cardiovascular measures from standardized stress testing (mental arithmetic, cold pressor test) in the laboratory and 24-h ambulatory recordings of blood pressure and the heart rate. The basic relationship between laboratory and ambulatory recordings was calculated by correlating the mean of our laboratory values with 24-h mean ambulatory values. Laboratory readings of baseline and stress systolic blood pressure, diastolic blood pressure and the heart rate correlated significantly (P less than 0.05) with ambulatory recordings of 24-h means and short-period means (e.g. baseline systolic blood pressure with work mean, r = 0.33; with mean, r = 0.33). However, the correlations were no closer than the basic relationship between laboratory examinations and ambulatory recordings (r = 0.41 for systolic blood pressure; r = 0.46 for diastolic blood pressure; r = 0.43 for heart rate). There was no specifically close correlation between laboratory baseline and the corresponding ambulatory rest phase (evening, sleep) or between laboratory stress values and ambulatory phases of high demand (work mean). Reactivity measures in the laboratory (stress values-baseline values) were correlated to measures of variability in ambulatory recordings (standard deviation; coefficient of variation; maximum, minimum value; range), but, again, there was no specific effect separating similar from non-similar phases. We conclude that laboratory measures have no specific bearing on ambulatory blood pressure and heart rate measures.