Ambulatory blood pressure monitoring and clinical characteristics of the true and white-coat resistant hypertension

The resistant hypertension has been differentiated in true resistant hypert ension and white-coat resistant hypertension by using ambulatory blood pres sure monitoring. White-coat resistant hypertension was defined as high clin ic blood pressure, despite triple treatment for at least 3 months, but day- time blood pressure values < 135/85 mmHg. The aim of this study was to eval uate the presence of different clinical characteristics between two types o f resistant hypertension. The study group consisted of 49 patients with essential hypertension, resis tant to an adequate and appropriate triple-drug therapy, that included a di uretic, with all 3 drugs prescribed in near maximal doses and that had pers istently elevated clinic blood pressure (> 140/90 mm Hg), for at least 3 mo nths. They represented the 2% of 2500 hypertensive outpatients that referre d at our Hypertension Unit. Patients with white-coat resistant hypertension (n=19) were older (p <0.05) than those with true resistant hypertension (n =30). The sodium intake (p <0.05) and alcohol intake (p <0.05) were signifi cantly higher in patients with true resistant hypertension than in those wi th white-coat resistant hypertension. The renin plasma activity and plasma aldosterone were higher (p <0.05) in patients with true resistant hypertens ion than in those with white-coat resistant hypertension with normal plasma electrolyte balance. There were no significant differences in mean values of office systolic and diastolic blood pressures between white coat resista nt hypertensives and true resistant hypertensives ( 165+17 vs 172+28 and 98 +12 vs 102+14 mmHg). Day-time and night-time ambulatory 24-h-systolic and diastolic blood pressu res were significantly higher in the true resistant hypertensive patients w hen compared with white-coat resistant hypertensives (153+15 vs 124+10 mmHg and 97+9 vs 76+6 mmHg all p <0.001). Day-time and night-time ambulatory 24 -h-heart rate were significantly higher in the true resistant hypertensive patients when compared with white-coat resistant hypertensives (79+11 vs 71 +9 beats/min ;p <0.01; 68+9 vs 60+6 beats/min. p <0.001). The ABP readings were analysed by a Fourier series with 4 harmonics. According to the runs t est both two groups of patients showed a circadian rhythm for both systolic and diastolic blood pressure. The nocturnal fall in SEP, DBP and HR was no t different in both groups of patients. In conclusion, our findings showed that true resistant hypertensive patient s were characterized both by higher heart rate and higher plasma renin acti vity values as an expression of a possible increased sympathetic activity. Thus, the combination of ABPM with the assessment of the clinical character istics allow to differentiate better the true drug-resistant hypertension f rom the white coat resistant hypertension.