Relationship between variability of arterial blood pressure from ambulatory 24-hour monitoring of arterial blood pressure with echocardiographic parameters in patients under antihypertensive therapy

Abstract

Introduction: Variability of systolic daytime arterial pressure was until recently a controversial parameter but is now recognized as an independent prognostic risk factor for stroke in hypertensive patients. Blood pressure variability is a quantitative index of spontaneous daily and nocturnal variations in systolic and diastolic arterial blood pressure and has been proposed as a risk factor for inducing subclinical damage to target organs in arterial hypertension. Besides varying degrees of left ventricular myocardial hypertrophy (LVH), patients with hypertension also exhibit accompanying diastolic dysfunction of the left ventricle as an early sign of hypertensive damage, even when myocardial hypertrophy does not develop. The variability of pressure over 24 hours in Ambulatory Blood Pressure Monitoring (ABPM) has not been sufficiently studied in terms of correlation with echocardiographic parameters in controlled hypertension. Methods: A total of 196 adequately treated patients with stage 2 hypertension, with a target of achieving normotension less than 140/90, were examined. The total of 196 patients, 109 males and 87 females, with a mean age of 49.3 ± 8.4 years, untreated or inadequately treated patients with stage 2 hypertension (mean BP before treatment 167/106 mmHg) were divided into three groups according to blood pressure variability parameters. Alongside standard methods: medical history, clinical examination, and electrocardiogram (ECG), 24-hour ambulatory arterial pressure monitoring (ABPM, so-called blood pressure holter) was performed with 24-hour, daytime, and nighttime variability of systolic and diastolic blood pressure as well as Color and Tissue Doppler echocardiography after adequate treatment. Results: Elevated blood pressure variability was observed in 66/196 patients (34%) in group V despite good pressure regulation, while 130/169 (66%) had normal variability - group C (control). A subgroup ExtV was particularly highlighted within group V with extreme variability of daytime systolic BP (SD>20 mmHg) - 15/66 patients (8%). Evaluation of left ventricular myocardial mass index (LVMI) showed no difference in the degree of LVH between groups C and V. In the subgroup ExtV (from group V with extreme blood pressure variability), comprising 15/66 patients (8%), a significant difference in the degree of left ventricular myocardial hypertrophy was found between groups C and V regarding extreme variability (p<0.01). There was no difference concerning gender and age structure. Statistical analysis of investigated 24-hour blood pressure parameters and echocardiographic parameters did not show significant correlation through calculation of the linear correlation coefficient between mean arterial pressure measured by 24-hour ambulatory pressure monitoring and standard deviations of daytime and nighttime pressure and the degree of left ventricular myocardial hypertrophy (linear correlation coefficients r <0.20), as expected. However, there is a moderate but significant correlation between the best echocardiographic parameter of diastolic function, E/E' ratio, and variability of daytime systolic pressure: r= 0.41. Only the subgroup with extreme variability ExtV in terms of daytime systolic pressure has a statistically significant correlation with the degree of LVMI myocardial hypertrophy, r=0.51. Conclusion: One-third of the examined patients, 66/196 patients (34%) in group V, had elevated blood pressure variability despite good pressure regulation. There was no significant difference in the degree of left ventricular myocardial hypertrophy between the investigated parameters of 24-hour blood pressure and echocardiographic indices, except in extreme variability ExtV (P<0.01). However, there is a moderate but significant correlation between the best echocardiographic parameter of diastolic function, E/E' ratio, and variability of daytime systolic pressure: r= 0.41. Only the subgroup with extreme variability ExtV in terms of daytime systolic pressure has a statistically significant correlation with the degree of LVMI myocardial hypertrophy, r=0.51.