Many cardiovascular diseases have been related to increased oxidative stress and subsequent alterations in cardiomyocyte function and/or viability. As increased oxidative stress might also modify non-cardiac proteins, quantitative relationships between plasma proteins modified by reactive oxygen species and contractile abnormalities might be of interest and become a diagnostic tool but have hardly been established yet. In the past few decades, several urine and serum biomarkers have been identified but the diagnostic reproducibility of these tools as well as the scarcity of data evaluating their potential role in heart failure development/progression is currently limited. Therefore, alternate biomarkers of oxidative stress and their relation to cardiac disease, especially heart failure, are discussed and two novel plasma protein targets of oxidation – derived from experimental studies – are identified.