Intemutionul Jounzal of‘ Cardiology, 34 ( 1992) 335-33X ;i‘) 1997 Elsevier Science Publishers B.V. All rights reserved 0167-5273/92/$05.00

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CARD10 01403

Blood pressure load determines left ventricular mass in essential hypertension

Frank Bauwens, Daniel Duprez, Marc De Buyzere and Denis L. Clement Department of Cardiology and Angrolo~y. lJnilwsi@ Hospiral. Ghent, Belgmm

(Received 20 June 1991; revision accepted IO October 1991)

Bauwens F, Duprez D, De Buyzere M, Clement DL. Blood pressure load determines left ventricular mass in essential hypertension. Int J Cardiol 1992;34:335-338.

In a series of 35 newly diagnosed, previously untreated patients (mean age 46 years) with mild to moderate essential hypertension, office blood pressure measurements, 24-hour ambulatory blood pres- sure monitoring, and determination of left ventricular mass index by echocardiography according to the formula of Devereux were performed. We aimed at correlating left ventricular mass index with systolic and diastolic office blood pressure, mean 24-hour systolic and mean 24-hour diastolic blood pressure, systolic and diastolic load. Left ventricular mass index did not correlate with office systolic and office diastolic blood pressure. On the contrary, all correlations with ambulatory blood pressure parameters and left ventricular mass index turned out to be significant (mean 24-hour systolic blood pressure: r = 0.344, P = 0.026; systolic load: r = 0.408, P = 0.020; mean 24-hour diastolic blood pressure: r = 0.490, P = 0.004; diastolic load: r = 0.504, P = 0.003). These results clearly demonstrate that ambulatory blood pressure determinants but not the ofice blood pressure parameters are well correlated with left ventricular mass index in mild to moderate essential hypertension. Blood pressure load is as important as mean 24-hour blood pressure in this regard.

Key words: Ambulatory blood pressure recording; Essential arterial hypertension; Blood pressure load; Left ventricular mass index

Introduction

Left ventricular hypertrophy is a frequent and serious complication [1,21 of chronic systemic hy- pertension. It may be regarded as a compensatory process which, for some time, maintains the car-

Correspondence to: D. Duprez. M.D., Dept. of Cardiology

and Angiology. University Hospital, De Pintelaan 185, 9000

Ghent. Belgium.

disc function and performance in spite of the increased ventricular afterload caused by sus- tained high blood pressure 131. A large number of studies 14-61 have examined the relationship be- tween blood pressure level and the severity of left ventricular hypertrophy. The main finding is that the degree of hypertrophy is more closely related to the mean 24-hour blood pressure level ob- tained during ambulatory monitoring than to ca- sual blood pressure readings in the physician’s office. The aim of the present study is to examine

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which parameters from ambulatory blood pres- sure registration are best correlated with left ven- tricular mass, as determined by echocardiography [4,7,81.

Methods

Selection of patients

All consecutive patients were referred to our outpatient clinic for the evaluation of arterial hypertension. The patients did not take any med- ication and they all gave informed consent. Only those patients, who according to history, physical examination, routine blood and urine chemistry, renal scintigraphy, and appropriate hormonal studies, had essential hypertension were in- cluded. Concomitant cardiovascular disease other than hypertension (aortic stenosis, two patients; congestive heart failure, one patient) and other chronic diseases as diabetes mellitus (n = 12), liver disease (n = l), and renal disease (n = 3) led to the exclusion of the patient. Patients with disproportionate septal thickness (n = 3), as as- sessed by echocardiography were also excluded. All patients were evaluated on an outpatient base with an ambulatory 24-hour blood pressure regis- tration (one measurement every 30 minutes) dur- ing normal daily activities with an oscillometric device, Spacelabs Model 90207 (Spacelabs SARL, Paris, France) and an echocardiographic study Wingmed CFM 750, Horton, Norway; using a phased-array, 3.0 MHz transducer).

Blood pressure measurement

Hypertension was defined according to “The 1984 Report of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure”: diastolic blood pressure > 90 mmHg and systolic blood pressure > 140 mmHg [9]. During the physical examination, the blood pressure was measured with a mercury sphygmo- manometer three times, in the sitting position, with IO-min intervals, at the arm where the low- est value was found. The three values then were averaged and this value gave the “office blood

pressure” in systole and diastole. From the 24- hour blood pressure registrations, mean systolic and diastolic blood pressure and systolic and di- astolic “blood pressure load” [S] (% of the read- ings > 140 and > 90 mmHg, respectively) were withheld for evaluation.

Echocardiographic study

In the parasternal long-axis view, according to the criteria of the American Society of Echocar- diography [lo], septal wall thickness, posterior wall thickness, and left ventricular internal diam- eter at end-diastole were measured. These values then were used to calculate left ventricular mass, corrected for body-surface area, according to the formula of Devereux [ 111.

Statistical analysis

All study parameters are expressed as mean value + standard deviation. Blood pressure pa- rameters and left ventricular mass index are in- tercorrelated by the Spearman rank test. P val- ues of less than 0.05 were considered statistically significant in this study.

Results

Patient demographics

A total of 35 Caucasian patients (22 males) were included in the study. Their mean age was 46 years (35-75 years). The mean office systolic blood pressure was 164.7 + 20.6 mmHg, the mean office diastolic blood pressure was 102.1 + 9.6 mmHg. Twelve (34%) of these patients had nor- mal mean 24-hour blood pressure readings (sys- tolic and diastolic). In this group, the mean sys- tolic load was 31.4 f 11.2%, the mean diastolic load was 17.2 _t 8.3%. In the group of patients with elevated mean blood pressure the mean systolic and diastolic load was 65.2 f 22.3% (P < 0.01) and 58.9 + 18.2% (P < 0.011, respectively. The mean left ventricular mass index was 152.4 ) 22.3 g/m’ in this latter group, against 123.3 + 29.3 g/m’ in the former group (P < 0.05).

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5 > . ;200 -

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I . .

z . . . .

z .* d

. .

3

l .

.$lOO - .

. . ,a, ,,I

i . .

z . . I=0 11,

.

I 1 I I I I

0 20 40 60 60 100

Srrtolic load (X) Fig. 1. Correlation between systolic blood pressure load and

left ventricular mass index in mild to moderate essential

arterial hypertension.

Blood pressure and left ventricular mass index

No correlation could be found between office blood pressure and left ventricular mass index (office systolic blood pressure: r = 0.085, not sig- nificant; office diastolic blood pressure: r = - 0.140, not significant). Significant correlation could be found however when left ventricular mass index was correlated with 24-hour blood pressure measurements: mean 24-hour systolic blood pressure (r = 0.344, P = 0.026), mean 24- hour diastolic blood pressure (r = 0.490, P = 0.004). Systolic blood pressure load (r = 0.408,

I “E ‘,

a l

z200 - .

" z . . I ; Z g100 - . .

. . l

c 2

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0 20 40 60 80 100

Diastolic load (X)

Fig. 2. Correlation between diastolic blood pressure load and

left ventricular mass index in mild to moderate essential

arterial hypertension.

P = 0.020) and diastolic blood pressure load (r = 0.504, P = 0.003) showed even more important correlations (Figs. 1 and 2).

Discussion

The finding of a weak but significant correla- tion between left ventricular mass index and 24- hour blood pressure measurements, is concordant with other studies [4-71. Blood pressure load [8] has not been evaluated regularly in the past. In our study, diastolic blood pressure load is as important as mean 24-hour diastolic blood pres- sure. It has been demonstrated however, that the mean diastolic blood pressure can decrease well below the 90 mmHg upper limit of normal while the blood pressure load still exceeds 15% [7]. For optimal blood pressure control, it seems there- fore warranted not only to reduce the mean 24- hour blood pressures, but also the blood pressure loads [8]. In view of the correlations found in this study, such an approach might help achieve higher success rates in decreasing left ventricular mass t 121.

It is not surprising that only moderate correla- tions are found. First, the duration of the disease is often not exactly known. It has been shown that factors other than blood pressure (renin- angiotensin system, sympathetic nervous system) contribute to left ventricular hypertrophy [15]. The pressure response to exercise might play a role [13,14], explaining the occurrence of left ven- tricular hypertrophy in apparently normotensive men. Although the 24-hour blood pressure regis- tration was done during normal daily activities [4], a controlled exercise test was not performed.

The results of our study indicate that the de- gree of left ventricular hypertrophy is more closely related to indices of 24-hour blood pressure measurements. Blood pressure load is as impor- tant as mean 24-hour blood pressure in this re- gard.

Acknowledgements

We would like to thank Mrs. L. Packet for her excellent secretarial assistance and Mr. M. Gillis for making the figures.

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