Cath Lab Guide to Coronary Reactivity Testing in Non‑Obstructive CAD
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Part 1 | Session 4 4. ACh protocol and spasm testing
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Part 1 | Session 5 5. Nitrates, repeat physiology and IVUS
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Part 1 | Session 6 6. Final diagnosis and take home points
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Part 1 | Session 1 1. Case overview and prior workup
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Part 1 | Session 2 2. Indication and cath lab setup
Here, Dr Jay Robert Widmer (The McKinney Heart Hospital, US) shifts the focus to thermodilution based physiology using intracoronary and intravenous adenosine.
Dr Widmer demonstrates measurement of resting and hyperaemic transit times, distal coronary pressure, and calculation of fractional flow reserve, coronary flow reserve and index of microcirculatory resistance.
He explains why apparently “long” transit times or very high flow states can lead to misclassification, and how to interpret a normal FFR, normal CFR (~4) and low IMR in the context of microvascular disease assessment.
The chapter also highlights artefacts from wire position and bolus variability and how to mitigate them.
Key learning points
- Stepwise acquisition and interpretation of CFR and IMR using thermodilution in a non obstructive LAD.
- Recognizing patterns of normal epicardial physiology (normal FFR) with normal microvascular indices (normal CFR, low IMR).
- Common pitfalls: artificially low or high transit times, “high flow state” after vasodilators, and the impact on classification of microvascular dysfunction.
This expert level cath lab case features Dr Jay Robert Widmer (The McKinney Heart Hospital, US) demonstrating a complete invasive coronary reactivity testing protocol in a 25 year old woman with persistent chest pain, normal coronary CTA and non-obstructive findings.
Dr Widmer walks through step-by-step assessment of coronary microvascular function using thermodilution derived CFR and IMR, followed by acetylcholine-based spasm provocation, intracoronary nitrates, and adjunctive IVUS to evaluate for myocardial bridging.
Viewers will see practical discussion on access choice, wire positioning, interpretation of high flow states after nitroglycerin and adenosine, and how to integrate physiology and imaging when the epicardial coronaries are angiographically normal.
The case concludes with a structured approach to alternative diagnoses (pericarditis, non-cardiac chest pain) and how to counsel patients when invasive coronary function testing is normal.
This content is ideal for interventional cardiologists and advanced fellows managing INOCA, ANOCA, microvascular angina and vasospastic angina in a high volume cath lab setting.
This case was performed by Dr Thuy Pham Ryan and Dr Jay Robert Widmer.
Producer: Transcatheter Academy
Editor: Mirjam Boros
More from this programme
Faculty Biographies
Robert Jay Widmer
Interventional and Structural Cardiologist
Dr R Jay Widmer is an interventional and structural cardiologist and academic leader with extensive experience bridging clinical innovation and digital cardiovascular research. In 2018, he joined the Baylor Scott & White system in Temple, Texas, and now serves as Chief of Cardiology at Baylor Scott & White The Heart Group – McKinney, where he is guiding growth and development in the northeast DFW corridor. He also holds the title of Associate Professor at both Texas A&M and Baylor Colleges of Medicine. (SCAI)
Dr. Widmer completed his undergraduate degree at Southwestern University in Georgetown, Texas, before earning a combined MD/PhD from the Texas A&M Health Science Center in 2009. (SCAI) He entered the clinical research track at the Mayo Clinic in Rochester, Minnesota, and completed training in internal medicine (2012), general cardiology (2016), and interventional/structural cardiology (2018), achieving board certification in all three disciplines. (SCAI)…
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