Evaluating CMR

The metabolic syndrome is a progressive disorder

One of the major criticisms levelled against the concept of the metabolic syndrome is that it is progressive. The metabolic markers included in metabolic syndrome clinical criteria represent a set of continuously distributed variables, and it is very difficult to draw a line over a certain cut-off value to identify, for example, an individual with elevated triglyceride concentrations (high or low). Similarly, to be diagnosed with the metabolic syndrome using NCEP-ATP III criteria (which are widely accepted in the literature), one should have three or more out of five risk markers. Diagnosis of the metabolic syndrome therefore provides a “yes” or “no.” However, metabolic syndrome-related CVD and type 2 diabetes risk increases progressively based on the severity of the criteria. The current “all or none,” 3 out of 5 metabolic syndrome clinical criteria do not adequately address this linear relationship between components of the metabolic syndrome and CVD or type 2 diabetes risk.

Of course, the metabolic syndrome is a progressive disorder, and it is reasonable to believe that patients with many metabolic abnormalities are more likely to develop cardiovascular outcomes than subjects with fewer or less severe features of the metabolic syndrome. However, individuals with two or less features of the metabolic syndrome are not necessarily at lower CVD risk. Indeed, if these individuals have traditional risk factors, they are at increased CVD risk even though they were not diagnosed with the metabolic syndrome. Wilson et al. (9) tested this hypothesis in the Framingham Offspring Study and reported that participants with three metabolic traits were not necessarily at greater CVD risk than participants with two features of the metabolic syndrome.