Although heart disease is the leading cause of death in the United States, a significant portion of people who experience heart attacks are unaware that they have the underlying condition.

Cleerly, a cardiovascular imaging startup, hopes to fix this. By analyzing CT scans of the heart, the company’s AI software aims to identify early-stage coronary artery disease, similar to how mammograms and colonoscopies detect breast and colon cancer.

“The majority of people who will die of heart disease and heart attacks will never have any symptoms,” said cardiologist James Min who founded Cleerly in 2017. “At some point, we need to start screening the world for heart disease.” The company grew out of a clinical program that Min founded in 2003 at New York-Presbyterian Hospital/Weill Cornell Medicine.

Cleerly is currently running a large, multi-year clinical trial to prove that its screen can catch heart conditions in people without disease symptoms more accurately than other routine non-invasive methods such as measuring blood pressure and cholesterol levels.

If the company succeeds in gaining regulatory clearance to screen large populations, it could be a massive boon for the company, significantly expanding its market reach and revenue.

Such enormous potential has attracted significant investor interest. On Wednesday, Cleerly announced that it raised a $106 million Series C extension round led by Insight Partners and joined by Battery Ventures. The large capital haul comes a little over two years after Cleerly raised a $223 million Series C  led by T. Rowe Price and Fidelity.

An extension round is when a company sells off another chunk of itself at the previous round’s price. Although extension rounds are often a sign that the startup is not growing well (if they were, they would raise a new round at a higher valuation), Scott Barclay, a managing director at Insight Partners, said that Cleerly’s is growing fast enough. He said by allowing Insight to join a previous round, Clearly gains additional capital to finance future growth and multi-site clinical trials.   

Min told TechCrunch that while the company did not necessarily need additional capital, given that Cleerly’s other backers were healthcare VCs or crossover firms, it was excited to add Insight Partners, one of the largest enterprise software investors, to its cap table.

Barclay is confident in Cleerly’s potential. While the company awaits full FDA clearance for general heart screening, its algorithms have already been cleared for diagnosing symptomatic patients, and in October, Medicare approved coverage for its plaque analysis test. Plaque build-up is a common cause of heart attacks. 

Until recently, patients who complained of chest pains might have been diagnosed with a stress test, which involves monitoring heart function during physical activity or coronary angiogram, an invasive procedure that measures blood flow to the heart with a catheter and x-ray.

Cleerly claims that its AI-driven analysis of the CT scan image is less taxing on the body than a stress test or an angiogram, and by agreeing to pay for the test, health insurers and Medicare seem to agree.

The company’s software has been available commercially for the last four years, and over that period, Cleerly has had a compounded annual growth of over 100%, Min said. And the company is poised to continue its growth trajectory now that most payers recognize its diagnostic method for approximately 15 million people who present with heart problems each year, he added.

Cleerly isn’t without competition. Other companies that are working on AI-driven image analysis of heart plaque include HeartFlow and Elucid, but given that they all ultimately want to screen the entire population above a certain age, there is likely room for more than one winner in this market.