Clinical applications of echocardiography in myocardial and valvular heart disease

Is ventricular wall stress rather than left ventricular hypertrophy an important contributory factor to sudden cardiac death?

Sudden cardiac death comprises a significant proportion of cardiac mortality in Western society. Left ventricular hypertrophy has been identified by many authors as a possible risk factor for sudden cardiac death, however, left ventricular hypertrophy develops in response to external stimuli on the heart as a means of normalizing wall stress. It is possible that the fundamental abnormalities in wall stress, rather than the left ventricular hypertrophy itself, pose the increased risk of sudden death. Left ventricular hypertrophy, the consequence of raised wall stress, is easy to measure and easy to study and it is understandable why this parameter should have received more attention. Wall stress by contrast is difficult to measure, and worse, is variable throughout the ventricle so that it cannot be measured in a single quantifiable figure. As a consequence, only a limited amount of attention has been paid to wall stress as a possible trigger mechanism for cardiac arrhythmia. However, there is evidence from both basic and clinical research to suggest that raised wall stress may be a risk factor for sudden cardiac death and cardiac arrhythmia. This review discusses the evidence for and against left ventricular hypertrophy and wall stress as risk factors for sudden cardiac death, and also presents recent evidence that left ventricular hypertrophy in isolation can protect the heart against the arrhythmogenic effects of raised wall stress.