Background A widened electrocardiographic spatial QRS-T angle has been shown to be predictive of cardiovascular disease in HIV-infected individuals. However, determinants and risk factors of developing widened QRS-T angle over time in this population remain unknown. Methods and Results Spatial QRS-T angle was automatically measured from standard electrocardiogram of 1444 HIV-infected individuals without baseline widened spatial QRS-T angle from the Strategies for Management of Antiretroviral Therapy [SMART], a clinical trial comparing two antiretroviral treatment strategies [Drug Conservation (DC) vs. Viral Suppression (VS)]. Conditional logistic regression analysis was used to examine the association between baseline characteristics and incident widened spatial QRS-T angle (a new angle > 93 in males and > 74 in females). During 2544 person-years of follow-up, 199 participants developed widened angle at a rate of 7.8 per 100 person-years. In unadjusted models, female sex, black race (vs. white), DC treatment strategy, current and past smokers (vs. never), history of alcohol abuse, greater body mass index, history of diabetes and higher levels of hs-C-reactive protein were associated with incident widened spatial QRS-T angle. When these variables were entered together in the same model with adjustment for demographics and treatment strategy, DC treatment strategy [OR (95 CI): 1.50 (1.09, 2.07)], female gender [1.69 (1.17, 2.45)], current and past smoking (vs. never) [2.49 (1.63, 3.81) and 1.93 (1.21, 3.09), respectively], and diabetes [2.28 (1.33, 3.91)] predicted incident widened spatial QRS-T angle. Conclusions Drug conservation treatment strategy, female gender, smoking, and diabetes are independently predictive of incident widened spatial QRS-T angle in HIV-infected individuals.