Laboratory diagnosis of myocardial ischemia

The evaluation of myocardial metabolic changes in ischemic heart disease remains centered on the coronary sinus pacing and sampling techniques established over the last 25 years. Lactate remains the marker of choice for most institutions, though centers with more sophisticated laboratories will always be trying to improve on the sensitivity and specificity for ischemia, perhaps using ATP catabolites and nucleotides and measuring coronary sinus flow. The diagnostic value of lactate changes is limited and probably not superior to a well-conducted 12-lead treadmill exercise electrocardiogram test, but it does provide an objective marker for reliable further study and evaluation of interventions. It is almost certainly in the research context that metabolic studies have their place--evaluating drugs, surgery, or angioplasty and perhaps shedding light on obscure entities, such as chest pain with normal coronary arteries and cardiomyopathies. Attention to detail and simplicity of study are more likely to lead to valuable results rather than concentrating on the complexities. Each laboratory should establish the reproducibility of its results before commencing any procedures.