CAC Score and Coronary CTA

What is the best cardiac test for my patients? A common question that is debated by experts and impossible to answer without individual patient data. Let me give you my thoughts, in conjunction with cardiac guidelines, for the asymptomatic patient.

For years, physicians have based screening and additional testing on Framingham criteria. However, it does not always categorize patients accurately. Significant effort and funding has been allocated in finding better tests to truly identify intermediate to high-risk patients.

Asymptomatic patients walk into my office wanting confirmation that they are not going to have a heart attack, stroke or die in the near future. We discuss their risk, first utilizing the Cardiac Health Questionnaire that is printed on the CAC/CTA brochure. Patients, scoring 10 or more points understand they are probably in the intermediate risk category by Framingham criteria.

I give these intermediate to high-risk patients two options. I recommend an appropriate stress test and a Coronary Artery Calcium (CAC) score. The stress test rules out significant soft plaque that would not be identified on a CAC score. The CAC score is a screening test, consisting of a 10 second CT without contrast. Most patients will benefit from a CAC score, the exception being those under 40-45 years of age and those wanting to avoid radiation. In those cases, a CIMT (carotid intimal medial thickness) is recommended.

Patients with a CAC score over 100 are now at HIGH RISK and are actually “labeled” as having significant coronary artery disease. Recent data suggests CAC provides a 4-year window to use for individual patient risk stratification. More importantly, many clinical questions can now be quantified for the patient, such as whether they will benefit from statins, and establishing their LDL goal. However, patients need to understand that a CAC score is a screening test, not diagnostic, as is a Coronary CTA.

Understanding CT Angiography

The second option is a Coronary CTA also available at Prestonwood Imaging. The price is a very reasonable $595 and this is my recommendation to many patients who can justify the cost.

Let me explain the criteria we use for reading Coronary CTA, and then give examples of patient groups I will highly encourage to choose the Coronary CTA instead of the CAC and stress testing. Keep in mind, that the patient receives 80 cc of contrast during this 15-minute procedure. Renal function is assessed before the test but please notify the ancillaries if cGFR is less than 50.

The coronary artery portion of the CTA will be read into the following percentages. Remember, our total assessment includes showing the patient their heart chamber size and function, their valve status, any congenital findings, and ruling out tumors and clots.

  • Normal coronary arteries are defined as without soft plaque, calcified plaque, or complex dangerous plaque. One of the most rewarding parts of my day is showing patient’s their normal coronary arteries. (Their smile and now the irrelevant $595 cost are priceless.)
  • Minimal plaque is less than 25%. Importance is based on age and the psychological make-up of the patient.
  • Mild, non-obstructive plaque is 26-49%.
  • Borderline obstructive plaque is in 50-70% range. These patients will need stress testing, preferably the most sensitive (Cardiac PET) to assess if the plaque is limiting blood flow with exercise and thus needing further intervention. Of course, optimal medical therapy ensues.
  • Probable obstructive plaque is over 70%. These patients need urgent assessment often moving on to cardiac catheterization or maximal medical therapy and subsequent Cardiac PET to assess if medical therapy will potentially do well for the patient. Please read the “Courage Trial” comparing Lipitor versus intervention on patients with significant plaque.

The following patients are very amenable to the Coronary CTA option and often ask me to persuade them to have the test in a subliminal way. It helps significantly if their PCP recommended the Coronary CTA and they then hear confirmation from a cardiologist.

  • Patients wanting the best test to tell them everything. Some say cost is irrelevant, others don’t.
  • Patients who are the same age as a family member who died or had a cardiovascular event.
  • Patients tired of equivocal or non diagnostic stress testing or want to know if they have any blockage, especially over 70%.
  • Patients with continued chest pain, no matter their previous cardiac evaluation.
  • Patients whose cardiologist have recommended a catheterization and obviously don’t have coronary CTA as an option.
  • Patients who are alarmed at their score will want more information. Coronary CTA is an excellent option, but remember that the more calcium, the less the ability to visualize and quantify plaque. Patients with a score over 400 would benefit from physiologic assessment utilizing Cardiac PET.

Guidelines are published, and brochures are provided to make the educational process easy. There is no reason why every intermediate to high-risk patient shouldn’t be given the two options that could save their life, and at a minimum, help their PCP optimize their health. Please give your intermediate risk patients a CAC/CTA brochure and recommend these tests. Tell your patient to pick one.

Please contact me with any questions or thoughts.

Jim Rellas, MD