Single-view angiography measure of microvascular resistance linked to one-year outcomes in INOCA

Patients whose chest pain stems from narrowed heart vessels too small to see on angiography have long posed a diagnostic and prognostic puzzle. A new exploratory prospective cohort study, published in the European Journal of Medical Research, reports that a resistance index calculated from a single coronary angiographic view was independently associated with the risk of a composite clinical outcome over one year in this population, known as ischemia with non-obstructive coronary artery disease, or INOCA.

Patients with INOCA face an increased risk of adverse cardiovascular outcomes, a burden the study attributes largely to coronary microvascular dysfunction, or CMD. Because the microvasculature cannot be directly visualized with conventional angiography, simple and accessible markers for prognostic assessment in this population have remained limited, according to the study’s authors. The author list includes Zixin Zhang, Zhe Zhang, Weimeng Cheng, Lina Kang, Yuan Gao, Jingxi Wang and Zhonghai Wei, with Zhonghai Wei listed last.

The study enrolled 381 patients with non-obstructive coronary arteries who underwent coronary angiography for angina at the Department of Cardiology of Nanjing Drum Tower Hospital between June 2022 and July 2024.

The primary endpoint was a one-year composite clinical outcome, predominantly driven by recurrent angina. To analyze risk, the researchers computed an equivalent AMR value, abbreviated AMReq, and split the cohort into high-AMReq and low-AMReq groups based on the median value. The median AMReq in the study population was 97 mmHg s m−1.

During the one-year follow-up, 51 patients, or 13.4 percent of the cohort, experienced the composite outcome. Recurrent angina accounted for the majority of events at 11.8 percent, followed by non-fatal stroke at 1.0 percent and worsening heart failure at 0.5 percent. The dominance of recurrent angina in the composite endpoint is an important caveat when interpreting the findings, since the outcome measure is weighted toward symptoms rather than hard events such as death or myocardial infarction.

Patients in the high-AMReq group showed a significantly higher hazard of the composite outcome compared with the low-AMReq group, with a P value of 0.003. Kaplan–Meier survival analysis indicated that patients with AMReq above 97 mmHg s m−1 had a worse prognosis over the follow-up period.

In an adjusted multivariable Cox proportional hazards model, AMReq remained independently associated with the composite outcome, with a hazard ratio of 2.263 and a 95 percent confidence interval of 1.259 to 4.065, corresponding to P = 0.006. Restricted cubic spline analysis demonstrated a positive linear relationship between AMReq and the hazard of the composite outcome, suggesting that risk rose steadily across the range of measured values rather than at a discrete threshold.

The authors conclude that AMReq was independently associated with the one-year composite clinical outcome in patients with INOCA, an association predominantly driven by recurrent angina. They also note an open question: whether AMReq improves risk stratification beyond single-vessel AMR remains to be established, meaning the added value of the equivalent index over measurements from individual vessels is not yet settled.

Several limitations frame the findings. The study was conducted at a single center, Nanjing Drum Tower Hospital, and the authors describe it as exploratory. The composite endpoint was predominantly driven by recurrent angina rather than mortality or infarction, and the follow-up period was one year. The article was shared early as a peer-reviewed, accepted manuscript that is citable and carries a permanent DOI, with a final version of record to follow. As an observational cohort study, the results demonstrate an association between the angiographic resistance index and clinical outcomes; they do not establish that the index changes outcomes or that interventions targeting the microvasculature would alter prognosis.

Subject of Research: An angiography-derived microvascular resistance index and one-year outcomes in patients with INOCA

Article Title: Association of microcirculatory resistance index based on single-view coronary angiography with 1-year composite clinical outcome in patients with INOCA: an exploratory prospective cohort study

Article References: Zhang, Z., Zhang, Z., Cheng, W., Kang, L., Gao, Y., Wang, J., & Wei, Z. (2026). Association of microcirculatory resistance index based on single-view coronary angiography with 1-year composite clinical outcome in patients with INOCA: an exploratory prospective cohort study. European Journal of Medical Research. https://doi.org/10.1186/s40001-026-05385-7

Image Credits: AI Generated

DOI: 10.1186/s40001-026-05385-7

Keywords: INOCA, coronary microvascular dysfunction, angiography-derived microvascular resistance, AMReq, prospective cohort study, recurrent angina, Cox regression, restricted cubic spline, Nanjing Drum Tower Hospital, cardiology, prognosis, coronary angiography