Cardiovascular abnormalities are increasingly recognised among people newly diagnosed with HIV, but subclinical pathology may be challenging to diagnose. We present a case study of subtle cardiovascular changes in identical twins, one without HIV-infection and the other recently diagnosed with HIV (serodiscordant). We hypothesise that cardiovascular parameters would be similar between the twins, unless non-genetic (environmental) factors are at play. These differences likely represent occult pathology secondary to the effects of early HIV-infection. A 25-year-old female incidentally diagnosed with HIV, and her HIV-uninfected identical twin, living with her since birth, underwent comprehensive cardiovascular assessments. The HIV-positive twin exhibited a globular left ventricle (LV), larger LV volumes, decreased LV strain, peak atrial longitudinal strain (PALS) and higher native T1 and T2 mapping values compared to her sister. Cardiac biomarkers high sensitivity cardiac troponin T and N-terminal proBNP, as well as the novel markers of fibrosis and remodelling, galectin-3 and soluble-ST2, were higher in the HIV-infected twin. Given the twins' shared environment and genetic makeup, these differences likely stem from HIV-infection. Our study supports previous findings and suggests potential screening markers for HIV-associated cardiovascular disease, including PALS. Further research is warranted to explore PALS' utility in this context.