TUCSON, Ariz. (Feb. 10, 2026) -- As February marks American Heart Month, Banner – University Medicine Tucson is highlighting the importance of recognizing heart conditions that don’t always show up on standard tests, especially for patients who experience persistent chest pain without clear answers.
For 34-year-old Burton Schwartz, those unanswered questions lasted years.
When Schwartz enlisted in the U.S. Marine Corps in 2017, he was in peak physical condition and focused on building a long-term military career. But just a few years later, while stationed in Okinawa, Japan, his health took an unexpected turn.
Schwartz began experiencing episodes of rapid heart rate, chest pressure, palpitations and increasing discomfort while eating. The symptoms were persistent and intense. Despite seeking care from multiple experts, several doctors attributed his symptoms to anxiety.
"I'm a Marine. I don't usually have anxiety attacks. We get trained to deal with a lot of stress,” Schwartz said.
As time went on, his condition worsened.
After returning to the United States, Schwartz’s physical fitness declined significantly. Once able to meet the rigorous demands of military service, he began failing required physical fitness tests due to severe chest pain and pressure. Ultimately, the unexplained symptoms led to his medical separation from the Marine Corps after just four years of service.
It wasn’t until 2023, after years of pain, uncertainty and dismissal that Schwartz moved to Sierra Vista and finally met the physician who would uncover the true source of his symptoms.
That turning point came through interventional cardiologist Michel Corban, MD, who established coronary microvascular and endothelial function testing at Banner – University Medicine Tucson. The highly specialized diagnostic program is designed to identify heart conditions that often go undetected by traditional cardiac tests.
Dr. Corban is one of two Banner physicians in Arizona – the other being Ankar Gupta, MD, at Banner – University Medical Center Phoenix -- offering this advanced testing and treatment.
During American Heart Month, experts emphasize that not all heart disease presents the same way or appears on standard imaging.
“Some patients with ongoing, chronic chest pain, don’t have severe blockages in the big vessels of the heart,” said Dr. Corban. “About 50% of patients who come in with typical chest pain or a positive stress test have no blockages when we do an angiogram.”
While results of clear arteries may appear reassuring, it often leaves patients without an explanation for their very real symptoms.
The problem in these patients is in the small vessels of the heart, where 80% of blood flow happens. When they malfunction, patients can experience debilitating cardiac chest pain without any visible blockages in larger arteries.
Through coronary reactivity testing, Dr. Corban can directly assess how these small vessels function. For many patients, this testing delivers answers they have been seeking for years.
“When we do reactivity testing on patients with non-obstructive disease, about 65% turn out to have small vessel disease,” said Dr. Corban.
This testing is only available at a handful of major academic medical centers in the country.
For patients like Schwartz, receiving a diagnosis can be life changing.
“It felt like my heart was haunting me,” he said. “People need to advocate for themselves and seek help when they know something is wrong.”
About Banner – University Medical Center Tucson and South
Banner – University Medical Center Tucson and Banner – University Medical Center South are part of Banner – University Medicine, a premier academic medical network. These institutions are academic medical centers for the University of Arizona College of Medicine – Tucson. Included on the two campuses are Diamond Children's Medical Center and many specialty clinics. The two academic medical centers are part of Arizona-based Banner Health, one of the largest nonprofit health care systems in the country. Banner Health is in six states: Arizona, California, Colorado, Nebraska, Nevada and Wyoming. For more information, visit bannerhealth.com/universitytucson or bannerhealth.com/universitysouth.
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