BACKGROUND: Abnormalities of cardiac structure and function are common in patients undergoing dialysis, and cardiovascular disease is the major cause of mortality in this group. Heart failure is a common clinical manifestation of cardiovascular disease and is preceded by left ventricular hypertrophy (LVH). There are variable reports about the impact of dialysis on LVH, both deleterious and beneficial. Our study investigated whether the timing of the initiation of dialysis therapy had an impact on cardiac structure and function. STUDY DESIGN: Randomized controlled trial. SETTING & PARTICIPANTS: This is a cardiac substudy involving 182 patients with stage 5 chronic kidney disease in the IDEAL (Initiating Dialysis Early and Late) trial. INTERVENTION: The IDEAL trial randomly assigned patients on the basis of estimated glomerular filtration rate (eGFR), calculated using the Cockcroft-Gault equation, to start dialysis therapy early (GFR, 10-14 mL/min/1.73 m(2)), with the others starting late (GFR, 5-7 mL/min/1.73 m(2)). OUTCOMES & MEASUREMENTS: Echocardiograms were obtained at baseline and 12 months after randomization. Primary outcomes were change in left ventricular mass indexed for height (LVMi) between baseline and 12 months, left ventricular ejection fraction, left ventricular systolic annular velocity, ratio of mitral inflow velocity (E) to mitral annular velocity (Ea) (E/Ea), and left atrial volume indexed for height (LAVi). RESULTS: LVMi at baseline was elevated, but similar in both groups, with no significant change within or between groups at 12 months. E/Ea and LAVi were increased at baseline, consistent with significant diastolic dysfunction; there were no differences between groups at 12 months and no changes were observed for left ventricular volumes, left ventricular ejection fraction, stroke volume, and other echocardiographic parameters. LIMITATIONS: Small multicenter study using echocardiography. CONCLUSIONS: Advanced cardiac disease in these patients with stage 5 chronic kidney disease did not progress during the 12-month study period and planned early initiation of dialysis therapy did not result in differences in any echocardiographic variables of cardiac structure and function.