Echocardiography Assessment of Cardiac Structure

Echocardiography was also only carried out in participants attending the CRFs. Echocardiographic images were obtained using GE Vivid I machines from parasternal long axis and short axis, apical 5-chamber, 4-chamber, 3-chamber, 2-chamber and aortic views along with conventional and tissue Doppler in the 4-chamber view. Image analysis was carried out using GE EchoPac software. Wall and chamber measurements were made according to American Society of Echocardiography/European Association of Echocardiography guidelines^{32 (link)}. Measures of left ventricular (LV) structure used as outcomes in analyses were LV mass (LVM), LV end diastolic volume (LVEDV) and relative wall thickness (RWT) which are indicators of LV hypertrophy and remodeling. Indicators of LV diastolic dysfunction, an important risk factor for heart failure, calculated and used as outcomes were left atrial volume (LAV) (a marker of chronically elevated LV filling pressures), the ratio of early (E) to late (A) mitral inflow velocities (E/A), and the ratio of early (E) mitral to early (e′) myocardial velocities (E/e′) (an estimate of LV filling pressure)^{33 (link),34 (link)}.