Understanding the CardioRisk IMT Test
CARDIORISK INTIMA-MEDIA THICKNESS (IMT) TEST
The CardioRisk IMT (intima-media thickness) Test is performed to better assess one’s risk for a future adverse cardiovascular event. The results of the test are used in conjunction with other risk factors like one’s personal medical and dental history, family medical history, genetic screening, lab results (e.g., blood sugar, inflammation, and cholesterol), and blood pressure measurements to create a more comprehensive picture of an individual’s cardiovascular health. To read more about why someone should have a CIMT test performed, click HERE.
The test is conducted by having an ultrasound exam of the carotid arteries (neck arteries providing blood flow to the brain and face) by using a particular exam protocol. The images are sent to CardioRisk Laboratories for grading and reporting. CardioRisk Laboratories has the highest standards for exam protocol and reproducibility, making the CardioRisk IMT the preferred method for disease monitoring year over year.
CardioRisk Laboratories uses a computerized program that takes over 600 measurements of the thickness of the walls of the arteries. These measurements, in conjunction with your age and gender, are the information used to create the results of the report. The results are so precise, that when the test is performed by Nexus HealthSpan, a change of 0.01 mm, in either direction, is considered significant. The information in the report is read in four distinct sections. In order of significance, they include:
- The presence of plaque
- The presence of inflammation
- Arterial age
- Early Event Risk
Plaque, known as atherosclerosis, is defined by the CardioRisk Laboratories as intima-media thickness (IMT) of =1.30 mm. The risk values are either normal or high. The presence, or absence, of plaque is the most significant part of the report. Research has shown that the mere presence of plaque in the arteries poses the same risk for an adverse cardiovascular event as having already experienced a previous heart attack or stroke. Any individual with plaque present is treated as high-risk. The characteristic of the plaque, if present, is also important.
Inflammation, referred to in the report as the Average Common Carotid Artery (CCA) Mean and Average CCA Max, is defined by the laboratory as an increase in IMT above the alert value. The alert value is a specified cut-point based on one’s age and gender. A value is given for both the Average CCA Mean and the Average CCA Max. The risk values are either normal, moderate, or high. The Average CCA Mean is determined by a total of 600 measurements in the distal 1 cm of the CCA from 3 angles on both the left and right sides. The Average Max is determined by the average of the maximum measurement in each of the 6 angles measured.
Arterial Age is a coefficient of the average CCA Mean IMT measurement. It is listed to help one better understand the significance of physical measurements to them as an individual. There is no alert value given the type of calculation performed to determine the Arterial Age.
EARLY EVENT RISK
Early Event Risk is a little more complicated than the above metrics. The reported result is based on the single largest IMT measurement. The alert value differs based on an individual’s age. Early Event Risk refers to an individual’s increased risk of experiencing an adverse cardiovascular event over the next 5.1 years (±2.3 years). It does not suggest that an event will occur in the time frame; rather, the hazard ratio increases from 1 (Normal) to between 4.1 and 6.7 depending on a risk calculation called the Framingham Risk Score. A hazard ratio is a measure of association used in research. A hazard ratio of 1 confers no increased risk and ratios greater than 1 confer increased risk.