Cath Lab Guide to Coronary Reactivity Testing in Non‑Obstructive CAD
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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
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Part 1 | Session 3 3. Adenosine physiology: CFR and IMR
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Part 1 | Session 4 4. ACh protocol and spasm testing
In this chapter, Dr Jay Robert Widmer (The McKinney Heart Hospital, US) administers intracoronary nitroglycerin (up to 200 µg), demonstrating the expected epicardial vasodilation and discussing blood pressure safety considerations.
Dr Widmer then shows how nitrates can substantially shorten resting transit times, creating a high flow state that may artificially reduce calculated CFR and potentially misclassify patients if used before baseline physiology.
The team notes subtle systolic “milking,” prompting intravascular ultrasound with chromaflow to evaluate for myocardial bridging, which turns out to be absent. The chapter integrates nitrate effects, repeat physiology and IVUS findings into one coherent assessment.
Key learning points
- Hemodynamic and physiologic consequences of intracoronary nitroglycerin on resting flow, transit times and CFR.
- Why the timing of nitrate administration relative to CFR/IMR measurements matters for diagnostic accuracy.
- Role of IVUS (with chromaflow) in confirming or excluding myocardial bridging in patients with suspected systolic milking on angiography.
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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