Saliva Test Fast Tracks Heart Attack Diagnosis

Heart attacks need urgent diagnosis, followed by treatment to restore blood flow to blocked arteries. Diagnosis is based on symptoms (such as chest pain), an electrocardiogram (ECG) and a blood test for cardiac troponin, a protein released into the blood when the heart muscle is injured.

A saliva test could fast track heart attack diagnosis, according to a preliminary study. The innovative technique requires patients to spit into a tube and provides results in 10 minutes, compared to at least one hour for the standard blood test and saliva collection is a non-invasive.

Medical scientists at the Soroka University Medical Centre (Be’er Sheva, Israel) examined if cardiac troponin could be detected in the saliva of patients with heart muscle injury. Saliva samples underwent a unique processing procedure to remove highly abundant proteins. The processing procedure is called Saliva High Abundant Proteins Effective Depletion (SHAPED). A total of 32 patients with heart muscle injury (i.e. they had a positive cardiac troponin blood test) and 13 healthy volunteers were requested to provide saliva samples by spitting into a collecting tube. Then, half of each sample was processed, and the other half remained in its natural state. They then tested the processed and unprocessed saliva samples for cardiac troponin.

The investigators compared the results from the saliva samples (processed and unprocessed) with the blood samples. There was strong agreement between the blood findings and the processed saliva, but not saliva in its natural state. Most of the processed saliva samples tested were positive for troponin, compared to just 6% of the unprocessed saliva. Of the 25 patients with myocardial injury whose samples had advanced processing, 21 were confirmed positive for MI by both methods (sensitivity, 84.0%). Among healthy participants, no cardiac troponin was detected in the processed and unprocessed saliva samples.

Roi Westreich, MD, A Cardiologist and lead author of the study, said, “Since no test has been developed for use on saliva, we had to use commercially available tests intended for whole blood, plasma, or serum, and adjust them for saliva examination. This early work shows the presence of cardiac troponin in the saliva of patients with myocardial injury. Further studies are needed to determine how long troponin stays in the saliva after a heart attack. In addition, we need to know how many patients would erroneously be diagnosed with heart attack and how many cases would be missed.” The study was presented at the digital European Society of Cardiology 2020 congress held August 29 to September 1, 2020 via Sophia Antipolis, France.

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Soroka University Medical Centre