Prevalence of left ventricular hypertrophy and its associated risk factors in newly diagnosed hypertensive patients in Dar es salaam

Abstract

Introduction; LVH has been identified as an independent and significant risk factor for sudden death, acute myocardial infarction, and congestive heart failure. The risk increase is independent of other cardiovascular risk factors, including arterial hypertension. However high blood pressure remains to be the leading cause of LVH.

Objective; To describe prevalence and associated risk factors of left ventricular hypertrophy among newly diagnosed hypertensive patients in Dar es Salaam considering different geometric alterations of the left ventricle in relation to several variables such as age, sex, body mass index (BMI), family history of hypertension, cigarette smoking and alcohol status.

Materials and Methods; The study was conducted in all three municipal hospitals of Dar es Salaam region for 4 months, from July to October 2011. It was a descriptive cross -sectional study and involved 160 participants. Screening for hypertension was done by consecutive blood pressure measurements at medical outpatient department of the municipal hospitals. Dar es Salaam has three municipal hospitals which receive approximately about 800-1500 patients in a day (data from registry of these hospitals). Three quarter of patients attending are medical cases from dispensaries and health centers within the district. These municipal hospitals run several clinics including medical out patient, obstetrics and gynecology clinic, diabetes clinic and pediatric clinic. Newly diagnosed hypertensive patients were then referred to Muhimbili National Hospital, where physical examination, assessment to identify risk factors by using questionnaire was done and diagnosis of LVH was established by using electrocardiography and echocardiography. Newly diagnosed hypertension was defined as patients with systolic >140 mmHg and/or diastolic > 90 mmHg on the visit day or a known patient with hypertension on treatment not more than four weeks since diagnosis. Sokolow Lyon served as the criteria for the LVH. LVH was defined as a left ventricular mass index (LVMI) >112g/m² and >107g/m² in men and women, respectively. Data were entered using epidata version 3.1 and analyzed using SPSS version 16 and then summarized into frequency distributions tables, charts and correlation coefficient test.

Results; A total of 463 subjects were screened for hypertension 180 patients were recruited for the study, 20 subjects did not turn up for echocardiographic and electrocardiographic studies. Among 160 hypertensive subjects 68 (42.5%) were males and 92(57.5%) females. Prevalence of LVH was 115 (71.88%) of which 48 (41.7%) were concentric type and 67(58.3%) eccentric and 45 (28%) had normal echocardiographic findings. Majority of the study subjects were of primary school education (57.5%). Gender and age had an influence on the left ventricular geometric variation in contrast other factors like BMI, family history of hypertension, smoking habit and alcohol intake did not influence LV geometry in this study. The ECG sensitivity was 40% [CI 31.1-49.5%] and specificity was 82.22% [CI 67.4-91.4%]. Risk factors distribution between the young (<60years) and elderly (>60years) demonstrated insignificant difference in this study.

Conclusions; LVH is highly prevalent (71%) among newly diagnosed hypertensive patients. The left ventricular geometric alterations in these untreated patients are found to be influenced by age and sex with eccentric hypertrophy accounting for the majority (58%). ECG has low sensitivity but high specificity in detecting LVH.