Individual shear rate therapy (ISRT)—further development of external counterpulsation for decreasing blood pressure in patients with symptomatic coronary artery disease (CAD)

Abstract

Individual shear rate therapy (ISRT) evolved from external counterpulsation with individual treatment pressures based on Doppler ultrasound measurements. In this study, we assessed the effect of ISRT on blood pressure (BP) in patients with coronary artery disease (CAD). Eighty-four patients with symptomatic CAD were included in the study. Forty-one patients were enrolled for 6 weeks, comprising 30 sessions of ISRT; 43 age- and sex-matched patients represented the control group. The 24-h BP was determined by measuring the pulse transit time before and after 6 weeks of ISRT or the time-matched control. Participants were divided into three groups according to the 24-h BP before treatment: BP1 < 130/80 mmHg (normotensive); BP2 ≥ 130–140/80 mmHg (moderate hypertensive); BP3 > 140/80 mmHg (hypertensive). After 30 sessions of ISRT, the 24-h BP decreased significantly, whereas no changes were observed in the controls. The BP-lowering effect correlated with the 24-h BP before therapy (systolic: r = −0.78; p < 0.001; diastolic: r = −0.76; p < 0.001). In BP1, the systolic BP decreased by 4.3 ± 6.4 mmHg (p = 0.011), and the diastolic BP decreased by 4.8 ± 11.0 mmHg (p = 0.032); in BP2, the systolic BP decreased by 13.3 ± 7.5 mmHg (p < 0.001), and the diastolic BP decreased by 5.0 ± 7.5 mmHg (p = 0.002); and in BP3, the systolic BP decreased by 22.9 ± 11.4 mmHg (p < 0.001), and the diastolic BP decreased by 9.1 ± 9.5 mmHg (p = 0.003). Our findings demonstrate that ISRT reduces BP in patients with CAD. The higher the initial BP the greater the lowering effect.