The CV prognosis of short night blood pressure variability is important but still a matter of discussion. It is possible to analyse variability during the night or in relation to dipping of blood pressure day/night. The authors analysed this subject in an hypertensive population followed during 12.8 ± 5.1years
There were n = 1200 ambulatory blood pressure (ABPM) of hypertensive patients (645 women), ageing 51 ± 12 years, BMI 27 ± 5 Kg/m2, 53% under antihypertensive medication and without previous CV events. There were 251 CV fatal/non-fatal events (147 strokes, 67 coronary, 37 others CV). We determined the SD of 24 h Systolic blood pressure (SD 24 h SBP), and day and night of SD systolic blood pressure, respectively SD SBPd and SD SBPn. Also the systolic blood pressure dipping the day/night relation calculated has 100 x (1-sleep SBP/awake SBP ratio) expressed has a continuous variable. (SBPD).
In a multivariate Cox analysis, adjusted to age, gender, OBP, diabetes, BMI, CV therapy, SD SBPn: was predictive of CV events HR 1,29 (IC1.11–1,50), even adjusted to SD SBPd 1,32(IC 1,05–1.64) and SBPD 1,24 (IC1.05–1.47); for Stroke 1.33(IC 1.10–1,62) even adusted to SBPD 1,36 (IC 1.10–1.69), Coronary events 1,53 (IC 1.09–2.14), Global mortality 1.30 (IC1.04–1.64).
In a Kaplan Meier curve analysis free of CV events the higher the SD of SBPn the worst survival for CV events(log ranK 77,6,p < 0,000)Stroke (log rank 94,3, p < 0,000) coronary events (log rank 14,4,p < 0.05) CV mortality (log rank 67.4,p < 0,000), global CV (log rank 78,8, p < 0,000).
n a Portuguese population, the nighttime short term variability of BP was a powerful CV prognosis marker. It is plausible that nighttime BP variability is a more accurate indicator of BP load and of its CV consequences than in relation to dipping of blood pressure day/night.
1Universidade de Aveiro,Essua; Centro Hospitalar Baixo Vouga, Serviço Cardiologia, colaborador do CINTESIS, Aveiro, Portugal
2Centro Hospitalar Baixo Vouga, Serviço de Medicina Interna, Aveiro, Portugal
3Faculdade de Medicina do Porto, Investigador do CINTESIS, Porto, Portugal