Background: Coronary heart disease (CHD) patients require monitoring through ECGs; the 12-lead electrocardiogram (ECG) is considered to be the non-invasive gold standard. Examples of incorrect treatment because of inaccurate or poor ECG monitoring techniques have been reported in the literature. The findings that only 50% of nurses and less than 20% of cardiologists correctly place leads V1 and V2 of a standard 12-lead ECG is of great concern. Objective: The review discusses the evidence base underpinning the use of 12-lead ECG electrode placement on patients with suspected heart disease and summarizes the results of 10 research papers. Methods: The Cumulative Index to Nursing and Allied Health Literature (CINAHL), the British Nursing Index (BNI), Embase and Medline were searched, from 2000 up to May 2012 using the key words "electrocardiography", "positioning", "electrodes", "electrocardiogram", "lead placement" and "12-lead ECG". The search was limited to studies in the English language. The quality of each study was rated against set inclusion and exclusion criteria. Results: All the studies found that the incorrect connection of the electrode cables can alter ECG patterns simulating or concealing abnormalities, such as myocardial infarction (MI). Adherence to correct anatomical precordial lead placement methodology continues to be limited, especially with respect to leads V1 and V2 at the fourth intercostal space (ICS), which can potentially yield recorded waveforms that mimic the ECG diagnosis of septal MI. Conclusions: False ECG diagnosis of MI resulting from improper lead placement has the potential to trigger the wasteful use of healthcare resources and even cause harm to patients.