# Holter features to detect coronary artery spasm in ANOCA patients: A pilot study

## TL;DR

This pilot study explores how Holter monitoring can help detect coronary artery spasm in patients with non-obstructive heart disease.

## Contribution

The study identifies potential Holter-based features for diagnosing coronary artery spasm in ANOCA patients.

## Key findings

- Patients with CAS had more frequent ST depression per day compared to those without CAS.
- CAS patients showed lower heart rates and longer PQ times, especially at night or early morning.
- Discriminative ability of Holter features was limited, but the findings suggest potential for larger AI-based studies.

## Abstract

Illustration of the study flow of ANOCA patients who participated in the UMCU-IMPRESS pilot study and wore a Holter for 2-7 days between a study visit and coronary function testing (CFT), with the aim of discovering Holter-based measures with diagnostic potential for coronary artery spasm (CAS). The CFT resulted in a diagnosis of CAS or the absence thereof (No CAS). Patients with CAS had (1) a higher proportion of patients with at least one minute of ST depression per day, and (2) periods of lower heart rates and longer PQ times (most evident at night or early morning) than patients without CAS. Created in https://BioRender.com. Holter monitoring and coronary function test illustration: Colin Cramm.

Illustration of the study flow of ANOCA patients who participated in the UMCU-IMPRESS pilot study and wore a Holter for 2-7 days between a study visit and coronary function testing (CFT), with the aim of discovering Holter-based measures with diagnostic potential for coronary artery spasm (CAS). The CFT resulted in a diagnosis of CAS or the absence thereof (No CAS). Patients with CAS had (1) a higher proportion of patients with at least one minute of ST depression per day, and (2) periods of lower heart rates and longer PQ times (most evident at night or early morning) than patients without CAS. Created in https://BioRender.com. Holter monitoring and coronary function test illustration: Colin Cramm.

Coronary artery spasm (CAS), which can be epicardial and/or microvascular, is highly prevalent in patients with angina and non-obstructive coronary artery disease (ANOCA) undergoing coronary function testing (CFT). The CFT is invasive and limits larger diagnostics studies. We studied if Holter monitoring with symptom tracking identifies Holter-based CAS features with diagnostic potential in ANOCA patients.

42 ANOCA patients (88% female) were recruited in the UMCU-IMPRESS pilot study and wore a 12-lead Holter device for 2–7 days prior to CFT, with simultaneous symptom tracking. We compared symptoms and Holter-ECG characteristics between patients with and without CAS and calculated diagnostic measures for CAS using several thresholds for ischemia-related parameters.

33 Patients were diagnosed with CAS (79%). These patients more often had ≥ 1 min of ST depression in total per day compared to patients without CAS (≥0.035 mV: 88% vs 44%, p = 0.013; ≥0.040 mV: 73% vs 33%, p = 0.049), but discriminative ability was limited (AUC (95% CI): 0.65 (0.48–0.68)). Furthermore, patients with CAS had periods of lower heart rates and longer PQ and QT times than patients without CAS, most evident at night and early morning.

Patients with CAS more often demonstrated at least one minute of ST depression in total per day and exhibited periods of lower heart rates and longer PQ times mainly during the night and early morning compared to patients without CAS. Although discriminative ability was limited, we show that Holter monitoring may reveal signals in CAS patients, substantiating the need of large (AI-based) studies.