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| ORIGINAL ARTICLE |
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| Year : 2013 | Volume
: 10
| Issue : 1 | Page : 22-25 |
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Association between gender and left ventricular geometry in hypertension
Ehimwenma J Ogbemudia, Christopher O Iruolagbe
Department of Medicine, College of Medical Sciences, University of Benin, PMB 1154, Benin City, Edo, Nigeria
| Date of Web Publication | 21-Sep-2013 |
Correspondence Address:
Ehimwenma J Ogbemudia
Department of Medicine, College of Medical Sciences, University of Benin, PMB 1154, Benin City, Edo
Nigeria
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0189-7969.118576
Background: The left ventricle assumes different geometric patterns in hypertension. The effect of gender on cardiac remodeling in hypertension is not established as previous studies have reported conflicting results.
Objective: This study therefore seeks to determine the effect of gender on left ventricular geometric adaptation in hypertension.
Methods: This study was performed in the cardiac clinic of the University of Benin Teaching Hospital, Benin City, Edo State and it is a cross-sectional study. Echocardiography was carried out for 247 hypertensive subjects to determine their left ventricular geometry. Of these, 127 were females while 120 were males. The distribution of the left ventricular geometric patterns was then determined in each gender group.
Statistical Analysis: Continuous variables were expressed as means. Independent t-test was used to compare two groups while one-way analysis of variance (ANOVA) when more than two groups. Duncan multiple range test was then used to locate the source of difference. Categorical variables were expressed as percentages and the significance determined using the Chi-squared test. A P value of <0.05 was considered statistically significant.
Results: In women, the distribution of the geometric patterns were as follows eccentric hypertrophy (EH) 31.5%, normal geometry (NG) 18.9%, concentric remodeling (CR) 22%, and concentric hypertrophy (CH) 27.6%. The distribution in men was NG 25.8%, CR 16.7%, CH 33.3% and EH 24.2%. There was no significant association between gender and left ventricular geometry (P value=0.249).
Conclusions: Gender has no effect on left ventricular geometric adaptation in hypertension. Keywords: Gender, hypertension, left ventricular geometry
How to cite this article:
Ogbemudia EJ, Iruolagbe CO. Association between gender and left ventricular geometry in hypertension. Nig J Cardiol 2013;10:22-5 |
| Introduction | |  |
Systemic hypertension is the most common non-communicable disease in Nigeria [1] with prevalence of about 20%. [2] It is a chronic disease with major cardiac complications and it is associated with different left ventricular geometric adaptations. Four mutually exclusive geometric patterns have been described by Ganau et al., [3] They include normal geometry (NG), concentric remodeling (CR), concentric hypertrophy (CH) and eccentric hypertrophy (EH). These are defined by left ventricular mass (LVM) and relative wall thickness (RWT) on echocardiography. The earliest stage in hypertensive cardiac remodeling is CR followed by CH and then EH, which is the terminal stage. The first two geometric types CR and CH have increased RWT, but LVM is normal in CR and increased in CH. In EH, RWT is normal while LVM is increased. These geometric patterns were initially thought to have prognostic significance, but recent studies have shown that knowledge of left ventricular geometry provides little additional prognostic information beyond the LVM. [4],[5] These geometric changes are determined by varying degrees of hemodynamic stimuli (pressure overload) in an attempt to normalize elevated left ventricular systolic wall stress associated with systemic hypertension. Hypertensive cardiac remodeling ought to be a protective physiologic response, but it is associated with left ventricular hypertrophy (LVH), which is an independent predictor of cardiovascular morbidity and mortality in hypertensive patients and the general population. [6] Therefore, those geometric patterns with LVH (CH and EH) are associated with adverse cardiovascular outcomes.
The effect of gender in hypertensive cardiac remodeling has been investigated by other workers, but different results have been reported. These conflicting reports informed decision to carry out this study, which is designed to determine the effect of gender on left ventricular geometry in hypertensive patients.
| Materials and Methods | | |
This cross-sectional study was performed in the cardiac out-patient department of the University of Benin Teaching Hospital, Benin City, in Edo State. Subjects for the study were selected from recently diagnosed hypertensive patients (that is hypertension diagnosed within the last three months) referred to the cardiac clinic from a screening center in the Department of Preventive Medicine. They were referred immediately the diagnosis was made and so had not been exposed to antihypertensive drugs for long. Subjects with heart failure, valvular heart disease, ischemic heart disease, and diabetes mellitus were excluded from the study because these conditions would confound the results. Informed consent was sought from all subjects and approval of the Hospital Ethics Committee was obtained. Those found eligible were consecutively enrolled into the study.
The sample size for this study was calculated using the Fisher formula:
 , N=Minimum sample size, Z=Confidence interval, p=Prevalence of hypertension, q=1 − p, d=Error of margin. Prevalence of hypertension used was 20%. This gave a minimum sample size of 245. A total of 247 adult hypertensive subjects were enrolled into the study. Of these, 127 were females while, 120 were males. The subjects had their weights measured in kilograms on a standard beam balance with light clothing and their heights were taken in meters with an anthropometrical plane without shoes or headgear. A standard mercury sphygmomanometer was used to measure the blood pressure with the patient seated and after 5 min rest. The first and fifth Korotkoff sounds were taken as systolic and diastolic pressures respectively. Subjects with blood pressures greater or equal to 140 mmHg systolic and 90 mmHg diastolic were considered hypertensive. [7] The blood pressure was taken at one sitting because the diagnosis of hypertension had already been made at the screening center. Transthoracic echocardiography was carried out for each subject with a 3.5 MHz phase array transducer in the partial lateral decubitus position with ATL apogee 8,000 dynamic machine. The cardiac dimensions were taken on 2D guided M mode. The inter ventricular septum, left ventricular internal diameter (LVID), and posterior wall thickness (PWT) were measured in diastole using the leading edge to leading edge technique recommended by American Society of Echocardiography (ASE). The dimensions were taken thrice and the mean derived. LVM was derived from ASE formula [8] and then indexed to the allometric power of height. [9] LVM (g)=0.08 (1.04[IVSD + LVIDD + PWT] 3 - LVIDD 3 + 0.6) LVM>46 g/m 2.7 was considered as LVH [10] and RWT, which is the ratio of the posterior wall thickness PWT to LVID in diastole derived from this formula:
[17]
Values less than 0.45 were taken as normal RWT. [11]
Left ventricular geometry was defined from LVMI and RWT.
Normal LVMI and normal RWT=NG.
Normal LVMI with increased RWT=CR.
Increased LVMI and increased RWT=CH.
Increased LVMI and normal RWT=EH.
Statistical analysis was performed using the SPSS software version 16. Continuous variables were expressed as means±SD. Independent t-test was used to compare two groups and one-way analysis of variance (ANOVA) when more than two groups. Duncan multiple range test was then used to locate the source of difference where the P value was significant. Categorical variables were expressed as percentages and the significance determined using Chi-squared test. A P value of <0.05 was considered statistically significant.
| Results | | |
[Table 1] shows that the mean age (54.45±9.3) years of the study population was in the middle age range. Most of the patients were overweight with a mean body mass index (BMI) of 28.02±9.3 kg/m 2 .
The mean systolic and diastolic blood pressures were 178.2±13.5 mmHg and 104.1±7.6 mmHg respectively. [Table 2] shows that males and females subgroups were similar in terms of age and stage of hypertension P>0.05. The cardiac dimensions and derived variables on echocardiography varied significantly in the left ventricular geometric groups as shown in [Table 3]. EH was the most prevalent left ventricular geometric pattern (31.5%) in females while NG was the least prevalent 18.9%. In males, CH was the most common geometry 33.3% while CR was the least 16.7%. There was however no significant association between gender and left ventricular geometry P value=0.249.
| Discussion | | |
This study did not find any significant association between gender and left ventricular geometry in hypertensive patients, as shown in [Figure 1]. This implies that gender is not a major factor in cardiac remodeling in hypertension. This finding supports the fact that hemodynamic forces such as pressure overload are the primary determinants in hypertensive cardiac remodeling, which is mediated via neurohormonal factors such as epinephrine, angiotensin II, and aldosterone. [12] Sex hormones (estrogen, progesterone and testosterone) have not been shown to play a major role in hypertensive cardiac remodeling and so gender is not a major determinant of left ventricular geometry in hypertension. | Figure 1: Distribution of geometric patterns in relation to gender. Values expressed as percentages. P value = 0.249, X 2 = 4.116, df = 3. NG: Normal Geometry, CR: Concentric Remodeling, CH: Concentric Hypertrophy, EH: Eccentric Hypertrophy
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This result is in agreement with that of Masiha et al., [13] who reported that left ventricular geometric adaptation to a given hemodynamic load in hypertension are similar in both sexes. This common result is most probably due to similarity in the two study groups in terms of the distribution and prevalence of geometric patterns within the two gender groups.
However, Kolo et al.,[14] reported a different finding. They reported a significant association between gender and left ventricular geometry EH was associated with men while CH was associated with women. Krumholz et al., [15] also reported a similar finding.
Probable explanations for these conflicting reports are the differences in demographic variables in the study groups. For instance the blood pressure, it is known that left ventricular geometric adaptation matches systemic arterial pressure. CR and hypertrophy are associated with higher mean systolic blood pressure (SBP) compared to EH. [16] The mean SBP in this study (178.2±13.5) mmHg was significantly higher than that of Kolo et al., which was (159±19.8) mmHg.
The duration of hypertension is another important variable to consider because left ventricular geometry is gradually altered with time in chronic hypertension. The earliest geometric adaptation is CR followed by CH and then terminally EH. The patient with long-term hypertension (5 years and above) is therefore more likely to have abnormal left ventricular geometry associated with LVH compared with recently diagnosed hypertensive patients. Although the subjects enrolled in this study were recently diagnosed hypertensive all forms of geometry were present. This is not surprising because studies such as Adebiyi et al., [17] have reported a high prevalence of abnormal left ventricular geometric patterns even in recently diagnosed hypertensive patients.
Left ventricular geometry is also related to age. It is known that the prevalence of abnormal left ventricular geometry increases with age while, that of NG decreases. [18] The mean age in the study by Krumholz et al., was significantly higher than that of this study (54.45±9.3) years because they investigated only older hypertensive subjects above 50 years of age.
The method of standardizing LVM is also important. The prevalence and distribution of the left ventricular geometric patterns in hypertension varies with the method of normalizing LVM. [19] This study used height to standardize LVM, while Kolo et al. [14] and Krumholz et al., [15] used body surface area.
The limitations in this study include the difference in mean BMI between the male and female subgroup. It was a hospital based study so the results may not apply totally to the general population.
In conclusion, gender has no effect on left ventricular geometric adaptation in hypertension.
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[Figure 1]
[Table 1], [Table 2], [Table 3]
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