Prevalence of major electrocardiographic abnormalities in patients with hypertension in a primary care clinic in Hong Kong.

Background: Hypertension is strongly associated with cardiovascular events. Studies have shown that electrocardiographic (ECG) abnormalities were associated with increased risks for cardiovascular events. However local data is limited. The objectives of this study were: (1) to determine the prevalence of major electrocardiographic abnormalities in patients with hypertension in primary care in Hong Kong, and (2) to determine the association of major electrocardiographic abnormalities with patients' socio-economical background, cardiovascular disease and cardiovascular risk factors.

Methods: This was a cross-sectional study. Subjects were hypertensive patients aged between 18 and 80 who were enrolled in the Risk Assessment and Management Programme (RAMP) in a general outpatient clinic in Hong Kong. Outcome measures were prevalence of probable ischaemic heart disease (IHD), complete left bundle branch block (LBBB), left ventricular hypertrophy (LVH) and atrial fibrillation (AF) in patients with hypertension. The Pearson Chi-square test, independent t-test and Mantel-Haenszel test were used to measure the association between socioeconomic characteristics and cardiovascular risk factors, and ECG abnormalities.

Results: 504 hypertensive patients aged 18-80 were recruited in a general outpatient clinic. 6.3% had probable IHD, 0.4% had complete LBBB, 4.0% had LVH and 1.0% had AF. Probable IHD was associated with smoking (P = 0.032), hypercholesterolaemia (P = 0.037) and higher 10-year CV risk (P = 0.04). Complete LBBB was associated with smoking (P = 0.021) and hypercholesterolaemia (P = 0.022). LVH was associated with male gender (P = 0.001) and longer duration of hypertension (P = 0.035). AF was not significantly associated with any of the clinical or sociodemographic parameters.

Conclusions: This study showed that a significant proportion of patients with hypertension at the primary care setting in Hong Kong had probable ischaemic heart disease, left ventricular hypertrophy and atrial fibrillation. This finding is consistent with both overseas data and historic data in Hong Kong. The detection of electrocardiographic abnormalities is helpful in hypertension management by improving risk stratification.