Hello Health Rounds readers! Today is advanced diagnostics day at Health Rounds, as we highlight a pair of potentially practice-changing studies that were presented at large U.S. medical meetings. Both studies found newer methods to be superior to older, standard testing.

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A new testing protocol identifies patients whose chest pain is heart-related even though their main heart arteries look normal during typical exams, according to results of a new study.

During the usual coronary angiography testing procedure, patients lie on a table while doctors inject dye into the arteries that carry blood to the heart, looking for places in the larger vessels where flow of the dye is impaired or blocked.

“People may have real angina even when the main arteries appear wide open,” study leader Dr. Colin Berry of the University of Glasgow said in a statement.

When angiography is negative, doctors should consider using MRI to observe blood flow while patients are exercising, “especially in women, who are more likely to have small-vessel angina that otherwise goes unrecognized,” Berry said.

“By measuring blood flow with a stress cardiac MRI test, we found that small vessel problems were common,” he added.

In the study, 250 adults with chest pain but no blocked coronary arteries based on angiography all underwent stress cardiac MRI tests, his team reported at the just-concluded American Heart Association scientific meeting in New Orleans.

In half the group, the stress cardiac MRI results were shared with doctors and patients to help guide diagnosis and treatment. In the other group, results of the stress cardiac MRI were not disclosed and treatment decisions were based only on the results of the negative angiograms.

When doctors reviewed the stress cardiac MRI images, about half of participants were diagnosed with microvascular angina, compared with fewer than 1 in 100 when doctors relied only on angiogram tests.

More than half of those diagnosed with microvascular angina were women. The diagnosis was significantly linked with improved quality of life, the researchers also found.

“The results of our study open a new path for people with chest pain,” Berry said.

“Clinical practice should now change to include a stress cardiac MRI test for angina, especially for women with chest pain and no blockages in the main arteries.”

When there is a wide discrepancy between results of a newer blood test for evaluating kidney function and the results of an older test, the new diagnostic accurately identifies high-risk patients, researchers found.

The new test measures a protein called cystatin C. The older and still standard method for assessing the health of the kidney’s tiny blood filters, or glomeruli, involves blood tests for a waste product from muscle breakdown called creatinine.

However, creatinine levels depend in part on muscle mass, creating variability across age, sex, nutritional status, and medication use. Until recently, racially biased misconceptions about muscle mass led doctors to also consider skin color in interpreting kidney health based on creatinine levels.

New guidelines recommend consideration of cystatin C for estimating the glomerular filtration rate (GFR). Unlike creatinine, plasma levels of cystatin C are not affected by muscle mass, although they are affected by certain medical conditions.

In a new study of more than 800,000 patients in whom GFR was estimated using both cystatin C and creatinine, researchers saw wide discrepancies in some participants.

Overall, in 11% of outpatients, estimated GFR was significantly worse - at least 30% lower, indicating more advanced kidney disease – based on cystatin C measurement, researchers reported at the American Society of Nephrology Kidney Week 2025 meeting in Houston and in JAMA.

During follow-up for an average of 11 years, these patients had significantly higher rates of death, cardiovascular events, and need for dialysis or kidney transplant compared with patients without such significant discrepancies between cystatin- and creatinine-based estimates of renal function.

Similar discrepancies were also seen in 35% of hospitalized patients, but the implications in this group were not as clear as in the outpatients and more research is needed, the authors said.

“Our findings highlight the importance of measuring both creatinine and cystatin C to gain a true understanding of how well the kidneys are working, particularly among older and sicker adults,” study leader Dr. Morgan Grams of NYU Langone Health said in a statement.

“Evaluating both biomarkers may identify far more people with poor kidney function, and earlier in the disease process, by covering the blind spots that go with either test,” Grams said.

Healthcare systems that have successfully implemented in-house cystatin C testing have seen improved clinical decision-making, experts not involved in the study wrote in a JAMA editorial.

“Given its higher cost, cystatin C cannot fully replace creatinine measurement,” the editorial noted.