Do changes in dietary salt influence blood pressure of hypertensive patients pharmacologically controlled with verapamil? The Salt-Switching-Study (SSS).

To study how changes in dietary salt influence the blood pressure (BP) of pharmacologically controlled hypertensive patients, we have selected from a large multicenter trial two subgroups of 14 and 16 patients who attained BP control (office DBP < 90 mm Hg) after a 4-week treatment with verapamil SR 240 mg once daily, either under an unrestricted salt diet (high-salt; 14 patients) or under a moderately restricted salt diet (low-salt; 16 patients). All of them were switched to the opposite dietary salt regimen and continued on verapamil for 4 more weeks (Salt-Switching-Period). Office BP and ambulatory blood pressure monitoring (ABPM) were registered before and after the Salt-Switching-Period. Salt intake was checked by urinary sodium excretion (UNa). Patients switching from high- to low-salt reduced UNa from 180.9 +/- 22.9 to 89 +/- 28 mM Na/24h (P < 0.001) and patients switching from low- to high-salt increased UNa from 85 +/- 38.4 to 175.8 +/- 57.5 mM Na/24h (P < 0.001). No significant changes in BP were found by ABPM either in the group switching from high- to low-salt or in the group switching from low- to high-salt. In the latter group, a significant increase was observed in office DPB but not in SBP. Short-term changes in salt intake seem to have little influence on the BP of patients pharmacologically controlled with verapamil.