The ECG and left ventricular hypertrophy in primary care hypertensives

Abstract

Keywords: ECG; left ventricular hypertrophy; primary care hypertensivesWhilst cardiac hypertrophy is initially a compensatory response to the high blood pressure, the increased muscle mass outstrips its oxygen supply and coupled with the reduced coronary vascular reserve seen in hypertension, results in myocardial ischaemia even with normal coronary arteries. Thus beyond a certain point, left ventricular hypertrophy (LVH) secondary to hypertension becomes a major risk factor for myocardial infarction, stroke, sudden death, and congestive cardiac failure, 1 and this increased risk is in addition to that imposed by hypertension itself. Furthermore, hypertensives with LVH are at increased risk of cardiac arrhythmias (atrial fibrillation, ventricular arrhythmias) and atherosclerotic vascular disease (coronary and peripheral artery disease). 1 Patients with hypertension and LVH should therefore be identified for aggressive management, not only of blood pressure, but of all their cardiovascular risk factors.Epidemiological data regarding prevalence of LVH and the increased risk of cardiovascular mortality and morbidity was initially provided by the Framingham Heart Study more than 30 years ago, which employed ECG criteria to define LVH. 2 Conversely, the association between hypertension and LVH is also well-established, 3 leading to a particularly high cardiovascular risk for the uncontrolled hypertensive via the development of LVH. However, the correlation between blood pressures measured in the clinical environment and left ventricular mass is poor. 4 By contrast, 24-h ambulatory blood pressure monitoring (ABPM) provides a closer correlation between average daytime arterial blood pressure and left ventricular mass. 5 Many different criteria for identifying LVH exist, based on both echocardiographic (echo-LVH) and electrocardiographic (ECG-LVH) features, but there is considerable variation in sensitivity and specificity between these methods. 1,6,7 A commonly used screening test for LVH in hypertensives uses the 12-lead ECG and the Sokolow and Lyon criteria, that is, the sum of the S wave in lead V1 and the R wave in leads V5 or V6 on the ECG Ͼ35 mm, with a sensitivity of 22% and specificity of 79%. Other methods have also been evaluated: 6-9 (i) The Romhilt-Estes Point-Score System of у4 has a sensitivity of 12% and specificity of 87%; (ii) The Cornell system has a sensitivity of 31% and specificity of 87%; (iii) the Sokolow-Lyon Index (RaVL у1.1 mV) has a sensitivity of 18% and specificity of 92%; and (iv) the Rodrigez Padial system has a sensitivity of 82% and specificity of 8% respectively. These figures suggest that most forms of interpreting the ECG with regards to LVH are not useful as a screening tool. This can be marginally improved by multiplying QRS-voltage by QRS-duration, thus increasing the specificity to 96% and sensitivity to about 50%. 6,7 Crudely speaking, the features of LVH on ECG normally mean that true LVH is present, but its absence does not mean that LVH is absent. Nevertheless, the specificit...

Test Characteristics of Electrocardiography for Detection of Left Ventricular Hypertrophy in Asymptomatic Emergency Department Patients With Hypertension

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Accuracy of electrocardiography in diagnosis of left ventricular hypertrophy in arterial hypertension: systematic review

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