Echocardiographic epidemiology--an emerging tool for early diagnosis, studying pathophysiology, predicting prognosis, and testing treatments

Abstract

Advances in echocardiography mean that it is now possible to measure myocardial function accurately and non-invasively. Paradoxically, objective quantification of myocardial motion, contraction, and relaxation in each segment of the left ventricle actually makes it more difficult to define normality and disease in the individual patient, but the technique raises intriguing possibilities in population studies for diagnosing early heart muscle disease and testing new approaches to treatment. The catalyst to this approach was the development of tissue Doppler echocardiography to measure the velocity of myocardial motion, and then the processing of digitally stored velocity data to obtain measurements of regional myocardial deformation (strain and strain rate). Machines do not apply the Doppler equation when processing these signals, and so an alternative and more accurate term that encompasses all available methods is myocardial velocity imaging. Mogelvang et al. have reported their findings from performing echocardiography in >1000 subjects in the Copenhagen City Heart Study.1 These subjects comprised 17% of the total sample which had been drawn randomly from population registers, who attended when echocardiography with myocardial velocity imaging could be performed. They were aged between 20 and 93 years, and included substantial numbers of subjects with hypertension (>140/90 mmHg), diabetes [plasma glucose >11.1 mmol/L, or glycosylated haemoglobin (HbA1c) >7%, or on treatment], and/or ischaemic heart disease (IHD, diagnosed from history or abnormal ECG). Compared with ‘control’ subjects with none of these conditions, the subjects with hypertension, diabetes, or IHD had lower systolic velocities of long-axis shortening of the left ventricle (on average, –13%), less systolic mitral annular excursion (also –13%), and lower velocities of long-axis lengthening in early diastole (by an average of –33%). Overall, only 2% of the subjects with disease had a low ejection fraction (<50%) and only 8% had any degree of … *Corresponding author. Tel: + 44 29 2074 3489, Fax: + 44 29 2074 3500, Email: fraserag{at}cf.ac.uk