Prévalence et facteurs associés à la dilatation de l’oreillette gauche chez les patients hypertendus nouvellement diagnostiqués à l’Hôpital Général de Yaoundé.

J BOOMBHI^{1, 2,}, BC KAMENI LEUNI¹, AP MENANGA^{1, 2}, MN TEMGOUA¹, S KINGUE^{1, 2}

 

 

RESUME

 

Introduction : La dilatation de l’oreillette gauche (DOG) est une complication fréquente de l’hypertension artérielle. Dans notre milieu, où l’hypertension artérielle est le premier facteur de risque cardiovasculaire, nous n’avons retrouvé aucun travail sur le volume de l’OG indexé à la surface corporelle chez les patients hypertendus. Nous nous sommes donc proposer de déterminer la prévalence et les déterminants de la DOG chez les hypertendus nouvellement diagnostiqués à l’hôpital général de Yaoundé.

Méthode: Il s’agissait d’une étude transversale analytique réalisée pendant cinq mois de Mars à juillet 2019 à l’hôpital général de Yaoundé chez des patients âgés de plus de 18 ans sans autres maladies cardiovasculaires. Le volume de l’OG indexé à la surface corporelle supérieur à 34ml/m² était considéré dilaté suivant les critères de la Société américaine d’échocardiographie de 2015. Les données ont été analysées à l’aide du logiciel SPSS 23.0. Le seuil de significativité dans cette étude était fixé à 0,05. Une analyse bivariée puis multivariée en régression logistique a permis d’identifier les facteurs indépendants associés à la DOG.

Résultats: Cette étude a inclus 352 participants répartis en deux groupes : 176 hypertendus et 176 non hypertendus. L’âge moyen des hypertendus était de 54,3±13,3 années. Le sexe ratio était de 0,8. La prévalence de la dilatation de l’oreillette gauche évaluée par le volume de l’oreillette gauche indexé à la surface corporelle est de 24,4%. L’HVG concentrique augmentait dix fois le risque de dilatation de l’OG : OR 9,9 IC à 95%(2,5 – 39,3) P꞊0,001 et l’HVG excentrique augmentait 2,6 fois le risque de dilatation de l’OG : OR 2,6 IC à 95% (1,3 – 5,4) P=0,008.

Conclusion: : La prévalence de la dilatation de l’oreillette gauche évaluée par le volume de l’oreillette gauche indexé à la surface corporelle représentait le quart des hypertendus nouvellement diagnostiqués. La dysfonction diastolique et l’HVG concentrique étaient des déterminants indépendants de la dilatation de l’oreillette gauche.

 

 

MOTS CLES

 

Mots clés : prévalence, déterminants, dilatation oreillette gauche, hypertendu nouvellement diagnostiqué, Yaoundé.

 

 

 

SUMMARY

 

Background: Left Atrial Enlargement (LAE) is a frequent complication of hypertension. This situation can lead to rhythms disorders and thromboembolic complications. In our context, little is known about the prevalence and determinants of LAE in hypertensive patients. The purpose of this study was to determine the prevalence and associated factors of left atrial enlargement in newly diagnosed hypertensive patients at Yaoundé General Hospital.

Methods: We conducted a cross-sectional analytical study of five months duration from March to July 2019 at the Yaoundé General Hospital. This study included adults participants aged of at least 18 years old divided into two groups: hypertensive and non-hypertensive patients. Left atrial enlargement was defined as an indexed left atrial volume ≥ 34ml/m² using the criteria of the American Echocardiography Society 2015. Data was analyzed using SPSS 23 software. Simple and multiple logistic regression analysis were made to identify the independent risk factors of left atrium enlargement. The threshold level of significance in this study was set at p value <0.05.

Results: We included a total of 352 participants made of 176 hypertensive and 176 non hypertensive patients matched according to age and sex. The mean age of hypertensive patients was 54.3 ± 13.3 years. The prevalence of left atrial enlargement was 24.4%. Concentric left ventricular hypertrophy increased by 10-fold the risk of left atrial enlargement: [OR: 9.9 and 95% CI (2.5-39.3); p꞊0.001] and eccentric left ventricular hypertrophy increased by 2-fold the risk of left atrium dilatation [OR: 2.6 and 95% CI (1.3-5.4); p = 0.008].

Conclusion: The prevalence of left atrial enlargement accounts for a quarter of hypertensive patients. Diastolic dysfunction and left ventricular hypertrophy are important factors associated to left atrium enlargement.

 

 

KEY WORDS

Prevalence, determinants, left atrium enlargement, newly diagnosed hypertensive patients

 

 

 

1. Department of Internal Medicine and Specialties, Faculty of Medicine and Biomedical

Sciences, University of Yaoundé I, Yaoundé, Cameroon.

2. Cardiology Unit, General Hospital of Yaounde, Yaounde, Cameroon

 

Adresse pour correspondance 

Dr Jerome Boombhi, MD,

Department of Internal Medicine and Specialties,

Faculty of Medicine and Biomedical Sciences, University of Yaoundé I

Tel. +237 675814913

 Email: Cette adresse e-mail est protégée contre les robots spammeurs. Vous devez activer le JavaScript pour la visualiser. .  

 

 

INTRODUCTION

 

Hypertension is defined as a Systolic Blood Pressure (SBP) ≥ 140 and/or Diastolic Blood Pressure (DBP) ≥90 mmHg at the office. The global prevalence is 1.5 billion and this condition remain the leading cause of cardiovascular disease and all-cause mortality worldwide [1]. Longtime exposure to high blood pressure can lead to alteration of relaxation, left ventricle hypertrophy and left atrial enlargement (LAE). LAE is associated to several complications like heart failure, arythmia, thromboembolic disorders, sudden cardiac death and constitute therefore an independent cardiovascular risk factors [2][3]. This enlargement could be appreciated echographically by either antero-posterior diameter or atrial volume indexed to body surface area [4]. In Cameroon, the current prevalence of hypertension was 29.7% according to Kingue et al  in 2015[5]. Despite high burden of hypertension and related complications little is known about epidemiological profile of atrial enlargement in our context. This study should help to identify at risk groups in order to reinforce management accordingly.

 

 

MATERIEL AND METHODS

 

Study design, setting and participants

 

We carried out a cross-sectional study over a period of 05 months, from March to July 2019 at the cardiology departments of General Hospital of Yaoundé (GHY). Patients with following characteristics were excluded: pregnant women, moderate or severe valvulopathy, ischemic heart disease,congenital heart disease, atrial fibrillation, competitive athletes, patients with poor echogenicity. Sample size calculation was done by Cochrane formula [6].

 

N: minimal sample size

Z: 1.96 for an alpha error of 5%

P: Prevalence of LAE in a previous study ( 13%) [7]

D: precision set as 5%

A same number of participants in control group were retained. This group was made of non-hypertensive people matched according to age and sex.

 

Data collection

 

Using a structured pilot-tested questionnaire, we briefly interviewed all participants including hypertensive patient and matched control group before performing trans-thoracic 2D echocardiography. We collected following socio-demographic data: sex, age, matrimonial status, level of education, religion, profession, monthly income. Clinical data concerned: Cardiovascular risk factors such as history of alcohol or tobacco consumption, sedentary lifestyle, obesity defined as a body mass index ≥30 kg/m², dyslipidemia, hereditary exposure, duration of hypertension, weight, height, body mass index and clinical symptoms: dyspnea on exertion, palpitations, cough, thoracic pain, headache, blurred vision, dizziness. Prior electrocardiography was realized in all participants to evaluate electrics signs of LAE (bifid p wave with duration of 120 msec in D2 and/or predominance of negative part of p wave in V1).2D Transthoracic echocardiography using new generation echocardiographer of trade mark HITACHIARIETTAV70 with a 3.50MHz transductor was performed by experimented cardiologist to assess Left Atrial Volume (LAV) in 2 and 4 cavity views. Left Atrial Enlargement was defined as an indexed volume greater than 34ml/m² according to the American Echocardiography Society 2015. Also the values between 35-41 ml/m² , 42-48 ml/m² and >48 ml/m² were considered as mild, moderate and severe enlargement  [8].Other parameters were also assessed : diastolic Left Ventricular Diameter (dLVD), systolic Left Ventricular Diameter (sLVD), Interventricular Septal Thickness (IST), Posterior Parietal Thickness (PPT) and indexed Left Ventricular Mass (iLVM) according to Penn convention [9]. The cutoff for ILVM was set as 115 g/m² for men and 95 g/m²for women. According to the geometry of left ventricle, an increased left ventricular mass associated with Relative Parietal Thickness (RPT)>0.43 was considered as Concentric Left Ventricular Hypertrophy, and increased LVM associated with RPT<0.43 was considered as Eccentric Left Ventricular Hypertrophy. We have also measured Left Ventricular Ejection Fraction (LVEF) using Simplify Biplan Simpson’s formula, E wave, A wave, E/A ratio, Deceleration Time, Ea septal and lateral, E/Ea ratio, Isovolumetric Relaxation Time (IVRT), Vmax of tricuspid flux, inferior vena cava diameter.

 

Statistical Analysis

 

Data were analysed using SPSS version 23. Means (standard deviations), medians, interquartile range (IQR) were used to summarize continuous variables, while frequencies and proportions were calculated for categorical variables. Chi square and Fisher Exact Test were used to compare proportions. Mann Whitney and Kruskal Wallis were used to compare medians. The statistical significance was set at 5%.

 

 

RESULTS

 

 

We included a total of 352 participants made of 176 hypertensive and 176 non hypertensive patients. In hypertensive group we have 75 men (42.6%) and 101 women (57.4%). The mean age of hypertensive patients was 54.3 ± 13.3 years. There was not statistical difference with the matched control group (age=52.1± 7 years; p value= 0.09). Some cardiovascular risk factors were most prevalent in hypertensive group: history of chronic renal failure, alcohol consumption, sedentary life style, obesity and familial history of hypertension (Table 1). Theproportions of grade I, II, III hypertension were respectively: 16.5% (n=58), 17% (n=60), 16.5% (n=58). According to echocardiographical parameters, most hypertensive (73.9%) patients have grade I diastolic dysfunction. The prevalence of left atrial enlargement was 24.4% in hypertensive group compare with 0.6% in control group and the difference was statistically significant (p<0.001) (Table 2). Severe enlargement of the left atrium was more common in elderly participants 62.1 ± 17.5 (p = 0.021). There was not difference between severity of hypertension and left atrial enlargement: grade I (20.7%, p value= 0.418) grade II (23.3%, p value= 0.8) grade III (29.3%, p value= 0.29). In univariate analysis abdominal circumference (p=0.005), concentric left ventricular hypertrophy (p=0.001), eccentric left atrial enlargement (p=0.008), and diastolic dysfunction (p˂0,001) were associated with left atrial enlargement (Table 3). In multivariate analysis, only left ventricular hypertrophy and diastolic dysfunction remains significant (p˂0.001) (Table 4).

 

 

DISCUSSION

 

 

The aim of this study was to determine the prevalence and determinants of left atrial enlargement in newly diagnosed hypertensive patients at Yaoundé General Hospital. At the end of this work we have found that: The prevalence of left atrial enlargement was 24.4% and the main determinants were left ventricular hypertrophy and diastolic dysfunction. This prevalence was inferior to those of Milan et al in Italia who found a prevalence of 52% and Piotrowski et al who found a value of 57,2%. The difference is explained by the cutoff of left atrial enlargement which was set respectively at a left atrial volume of  31 and 22ml/m²[10]. Dzudie et al found in 2017 in Cameroon a prevalence of 26,9% in a population of 52 hypertensive patients using a non-indexed volume of left atrium [11]. The slight difference is due to the fact that non indexed method to appreciate the measure of left atrium may surestimate the real value. In Nigeria, Oladapo et al found a prevalence of 21,9% with an anteroposterior diameter [12]. It is well known that in term of accuracy the best tools for the determination of left atrial enlargement are respectively: Left atrial volume indexed to the surface area, left atrial surface and finally anteroposterior diameter in time [4].

The factors associated with left atrial enlargement were concentric and eccentric left atrial enlargement, diastolic dysfunction. Dzudie et al found in similar study that the only determinant of left atrial enlargement was diastolic dysfunction[11]. In fact hypertensive patients have at the earlier stage of the disease,  increase ventricular mass, anomaly of relaxation that lead to increase feeling pressure and secondary dilatation of the atrium[13]. In a systematic review done by Cuspidi et al in 2013, left ventricular hypertrophy increased by 3 folds the risk of left atrial enlargement[10].

We acknowledge some limits in this study; firstly, the fact that echographical measures were done by one operator may reduce generalizability of the result, secondly by using 2 D echocardiography the risk of subestimation could be raised. But, this study reinforces the fact that LAE is highly prevalent in our context and requires therefore a strict follow up in order to reduce complications.

 

 

CONCLUSION

 

The prevalence of left atrial enlargement is high in newly diagnosed hypertensive patients. Diastolic dysfunction and LVH are important associated factors of left atrium enlargement. Knowing the complications of LAE it is important to reinforce blood pressure control in patient who develops early predictor signs like diastolic dysfunction and LVH. The role of renin angiotensin system blockers may be interesting in such case to inverse the remodeling processes.

 

 

 

Table 1

 Distribution of cardiovascular risk factors in the population

 

Table 2

 Prevalence of left atrial enlargement according to different type of measure

APDLA: Left atrial antero-posterior diameter, LAS: Left atrial surface, iLAV: indexed Left atrial volume

 

Table 3

 Factors associated with left atrial enlargementin univariate analysis

 

Table 4

 Factors associated with left atrial enlargementin multivariate analysis

 

*LAE: Left atrial enlargement; OR: Odd Ratio; CI: Confident Interval

 

 

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