A zero calcium score is NOT an accurate predictor of cardiac events in patients with symptoms, but for those without symptoms, it’s over 95 percent.
A group of people with symptoms like chest pain and shortness of breath upon exertion undergo coronary calcium scoring and just happen to all get a result of zero, while a second group (equal number of people) with NO symptoms also undergoes the test, with a result of zero.
Does the calcium score of zero mean the same for both groups? NO.
“No medical test is perfect,” says Monica Reynolds, MD, a cardiologist with ColumbiaDoctors Medical Group in White Plains, NY.
“Every medical test is based on probabilities. Bayesian Theory, which takes into account pretest probability of disease in the interpretation of the results, must be applied.
“How likely is the patient to have the disease you are looking for – must be considered in interpreting any test result.”
It’s possible for a person with a moderate to high probability of heart disease to have a calcium score of zero, even though these patients usually (which doesn’t mean always) have high calcium scores.
Likewise, those with low pretest probability of heart disease will “likely,” says Dr. Reynolds, have a low calcium score—but not all will.
Comparing Asymptomatic Patients’ Zero Calcium Score with that of Symptomatic Patients
Dr. Reynolds points out a 2006 American Heart Association study of patients without symptoms who had a zero calcium score.
The zero calcium score “was associated with a very low risk for plaque (negative predictive valve 95-99%) and low cardiac event rate for the next five years (0.1 per 100 person-years),” she explains.
“However, in a 2008 study in Circulation in which symptomatic patients were studied, a zero calcium score was not nearly as predictive of good outcomes.”
This doesn’t mean that every single person with chest pain and/or shortness of breath, who has a zero calcium score, falls into the category of the collective result of the 2008 Circulation study.
One explanation is that in a group of “symptomatic” people, some will surely have non-cardiac origin of their symptoms.
“Bottom line – calcium scores are NOT definitive enough to use as diagnostic tool – which is why the professional medical associations do not recommend them as routine screening tests – which is why the insurance companies won’t cover the expense,” says Dr. Reynolds.
“If a patient is low-risk and asymptomatic, there is no conundrum – just relax and stick to a healthy lifestyle and diet. There is no need for a calcium score or a CT angiogram!”
Summary of Comparison of Asymptomatic and Symptomatic People with Zero Calcium Score
“In patients with no or minimal risk factors and no symptoms, a CAC of zero has a great negative predictive value of disease.
“In patients with multiple cardiac risk factors and/or symptoms to suggest coronary disease, a CAC is an INAPPROPRIATE TEST, as the negative predictive value is not helpful.”