CAD: Chronic Coronary Syndromes

1356742 - The Association of Heart Rate Response to Breathing Maneuvers in Ischemia with Obstructive Coronary Artery Disease (INOCA)—A Cardiovascular Magnetic Resonance Imaging Study

Wednesday, January 25, 2023

Location: E-POSTER

Presenting Author(s)

MK

Mahya Khaki, MD, MSc

MD, MSc
Research Institute of the McGill University Health Center
Montreal, Quebec, Canada

Primary Author(s)

MK

Mahya Khaki, MD, MSc

MD, MSc
Research Institute of the McGill University Health Center
Montreal, Quebec, Canada

Co-Author(s)

MB

Mitchel Benovoy, PhD

PhD
Area19 Medical Inc, Montreal, Canada, H2V 2X5
Montreal, Quebec, Canada
MS

Magdi Sami, MD

Prof of Medicine
McGill University Health Center
Montreal, Quebec, Canada
EH

Elizabeth Hillier, PhD

Research Scientist
McGill University, University of Alberta
Montreal, Quebec, Canada
RG

Ria Garg, MD

Research fellow
McGill University Health Center, United States
MM

Mayssa Moukarzel

Master's Student
Research Institute of the McGill University Health Center
Montréal, Quebec, Canada
Matthias G. Friedrich, MD, FSCMR

Senior Author
Research Institute of the McGill University Health Center
Montreal, Quebec, Canada
JL

Judy Luu, MD, PhD, FSCMR

Cardiologist
Research Institute of the McGill University Health Center, Canada

Background: In recent years, there has been increased recognition of patients presenting with signs and symptoms associated with angiographically normal or non-obstructive coronary arteries (< 50% stenosis), termed Ischemia with No Obstructive Coronary Artery Disease (INOCA)(1). Currently, an accurate and cost-effective diagnostic approach for the assessment of INOCA is lacking. Vasoactive breathing maneuvers with hyperventilation (HV) and breath-holds (BH), combined with Oxygenation-Sensitive Cardiovascular Magnetic Resonance (OS-CMR) imaging, have been shown to reflect coronary vascular function (2, 3). A retrospective study of the heart rate (HR) response to HV demonstrated the potential of a blunted HR response to differentiate between healthy individuals and patients with coronary artery disease (CAD) (4). In the present study, we aimed to compare in patients with ischemic heart disease, the association of heart rate (HR) response to breathing maneuvers and quantitative CMR adenosine perfusion (QP).

Methods:

We analyzed QP images acquired on a 3T GE in patients referred for clinically indicated adenosine first-pass myocardial perfusion imaging and invasive coronary angiography (ICA). Before the CMR scan, the HR response in healthy controls and patients was recorded while performing a 4-minute breathing maneuver, which included 2 minutes of normal breathing (NB), followed by 1 min of deep, paced HV (30 breaths/min), and a subsequent maximal voluntary BH, using an ECG sensor (EKG-Flex/Pro sensor-SA9306M, Thought Technology Ltd.; Montreal, Canada). The BH-induced HR recovery (HRR-BH) was calculated, defined as the percent change in the minimum HR during BH, relative to maximum HR during BH [(Max HR-BH – Min HR-BH)/ (Max HR-BH) *100)] (Fig. 1). All images were assessed for global quantitative stress myocardial blood flow (MBF) using cvi42 (Circle CVI Inc., Calgary, AB, Canada) (Fig. 2). INOCA was defined as < 50% coronary stenosis on ICA.

Results:

The analysis included 14 controls (43% males; age 51±11y) and 15 patients with both ICA and QP data, with INOCA diagnosed in 8 patients (50% males; age 60±5 y). There was no difference in global stress MBF between INOCA and obstructive CAD (Fig. 3A). INOCA patients had a significantly higher HRR-BH than patients with CAD. There was no significant difference in HRR-BH between healthy controls and the INOCA cohort (Fig. 3B). In logistic regression, those with increased HRR-BH were more likely to have INOCA (odds ratio 1.73; 95% CI 1.05–2.86, P=.03). This association was not observed with QP (odds ratio 0.55; 95% CI 0.07–3.94, P=.55).

Conclusion:

In this proof-of-concept study, the heart rate response to a simple breathing maneuver could differentiate patients with INOCA from patients with obstructive CAD. This fast, non-invasive, needle- and stress-free test may be useful as a complementary screening and diagnostic tool in the workup of patients with suspected ischemic heart disease.