Statins may prevent myocardial dysfunction associated with aging, and consequent atrial fibrillation (AF) and heart failure (HF). STAREE-HEART is a randomized, double-blind, placebo-controlled clinical trial assessing atorvastatin on markers of cardiovascular aging in a healthy older population. This ancillary study is nested in the STAtins in Reducing Events in the Elderly (STAREE) primary prevention trial. Participants ≥ 70 years (n=369) have been randomized to atorvastatin or placebo. Assessment at baseline and 3-years includes echocardiogram, electrocardiography and blood collection for biomarker assessment. The primary endpoint is change in global longitudinal strain (GLS), a measure of left ventricular systolic function. An estimated 184 participants per group enables detection of mean GLS at 3 years in the placebo group being 2.0 percentage points lower than mean GLS in the statin group at 3 years, assuming SD=5 percentage points and a 15% attrition rate, with power >90%. We present summary statistics describing participants at baseline. The mean age of the 369 STAREE-HEART participants was 73.0 years (SD 3.4). Mean left ventricular (LV) ejection fraction was 64.0% (SD 6.1), and mean GLS was 19.2% (SD 2.2). Mean GLS was similar between females and males (19.4 vs 19.0%) and slightly higher in those aged 70-74 compared to ≥75 years (19.4 vs 18.6%). AF was detected on screening in 4.5% of participants. The STAREE-HEART ancillary study will provide mechanistic detail concerning myocardial dysfunction and its consequences, to determine if atorvastatin affects left ventricular systolic function associated with aging. Clinical trial registration clinicaltrials.gov Unique identifier NCT04536870.