Nitrate Testing for Coronary Artery Spasm

(CRT-NITRO Trial)

Overseen By Bonnie Ostergren

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Baylor Research Institute

Must not be taking: Long-acting nitrates, PDE-5 inhibitors

Disqualifiers: Coronary artery disease, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 1

Duration: Intra op

50 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial examines how well the heart's blood vessels function in individuals with chest pain not caused by blocked arteries. It employs a special test with nitroglycerine (a type of nitrate) to observe changes in heart blood flow. The goal is to understand changes in blood flow and resistance in the heart's smaller vessels. Individuals who frequently experience chest pain without artery blockages may be suitable candidates. Participants must follow the study steps and agree to participate. As an unphased trial, this study provides an opportunity to contribute to important research that could improve understanding and treatment options for chest pain.

Will I have to stop taking my current medications?

You may need to stop taking long-acting nitrate therapies and PDE-5 inhibitors (like sildenafil or tadalafil) at least 48 hours before joining the trial.

What prior data suggests that intracoronary nitrate testing is safe?

Research has shown that intracoronary nitroglycerine is usually well-tolerated. In a study with 140 patients, only 3.5% experienced a noticeable reaction, which doctors then treated. This indicates that most people handle it well. Some possible side effects, such as low blood pressure, slow heart rate, trouble breathing, and flushing, are known but uncommon. Since intracoronary nitroglycerine is already used in some medical settings, extensive safety information is available. Always discuss any concerns with a doctor before joining a trial. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about intracoronary nitrate testing for coronary artery spasm because it offers a direct and precise way to assess coronary artery function. Unlike current treatments that may focus on symptom management, this method uses intracoronary nitroglycerine to measure coronary reactivity and pinpoint artery spasms effectively. By providing detailed insights into coronary flow reserve and microvascular resistance, this technique could lead to more tailored and effective treatment strategies for patients experiencing coronary spasms.

What evidence suggests that intracoronary nitrate testing is effective for coronary artery spasm?

Research has shown that intracoronary nitroglycerine effectively treats spasms in the heart's arteries. It relaxes and widens these blood vessels, relieving artery narrowing and preventing unnecessary heart procedures. In this trial, participants will undergo coronary reactivity testing with and without intracoronary nitroglycerine to assess its impact on blood flow. Studies have demonstrated that intracoronary nitroglycerine can quickly and safely improve blood flow through the heart's arteries. This treatment also aids in diagnosing heart artery issues by enhancing blood flow, making it easier to identify potential problems. Overall, intracoronary nitroglycerine has improved heart function in people with blood flow issues in the heart's arteries. ^{1 2 3 6 7}

Are You a Good Fit for This Trial?

This trial is for adults being evaluated for angina without obvious coronary artery disease, who can follow the study plan and give written consent. It excludes those with prior heart interventions, recent nitrate or PDE-5 inhibitor use, significant health risks as judged by doctors, minors, prisoners, pregnant individuals, and anyone unable to consent.

Inclusion Criteria

Patient being evaluated for ANOCA or INOCA

Patient should be able to comply with the protocol

Provide written informed consent before study participation

Exclusion Criteria

Any other condition or co-morbidity which, in the opinion of the investigator or operator, may pose a significant hazard to the subject if he or she is enrolled in the study

I have heart disease affecting my arteries.

I have had procedures done on my heart's arteries.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Treatment

Participants undergo coronary reactivity testing with and without intracoronary nitrate administration

Intra op

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Intracoronary Nitrate Testing

Trial Overview The study examines how blood flow in heart arteries responds before and after using a nitrate drug during a coronary reactivity test. This helps understand if nitrates affect measurements like CFR and IMR that assess heart blood flow issues.

How Is the Trial Designed?

Group I: Coronary Reactivity Testing with and without intracoronary nitroglycerine Experimental Treatment 1 Intervention

CRT will be performed in the left anterior descending and right coronary arteries. The following measures will be obtained in each of the coronaries first without intracoronary nitrates followed by a dose of 200-500 mcg of intracoronary nitrates and repeat measurements: * Coronary flow reserve (CFR) (normal \> 2.0) * Index of microvascular resistance (IMR) (normal \<25) * Resting ratio of distal coronary pressure to aortic pressure (Pd/Pa) (normal \< 0.91) * Resting and hyperemic (using intravenous adenosine) transit time (Tm) * Resting full-cycle ratio (RFR) * Hyperemic (using intravenous adenosine) fractional flow reserve (FFR) * Resistive reserve ratio (RRR)

Who Is Running the Clinical Trial?

Baylor Research Institute

Lead Sponsor

Trials

210

Recruited

205,000+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC9484227/

Intracoronary injection of nitroglycerine can prevent ... Intracoronary nitroglycerine administration can efficiently relieve coronary stenosis and prevent unnecessary PCI.

2. clinicaltrials.gov clinicaltrials.gov/study/NCT06896903?term=NITRO-BID&rank=3

Analysis of Coronary Reactivity Testing With and Without ... The primary outcome will be comparing the variables assessed by CRT with the primary outcome being CFR before and after nitroglycerin administration. The ...

3. withpower.com withpower.com/trial/phase-coronary-reactivity-testing-3-2025-7eb66

Nitrate Testing for Coronary Artery Spasm (CRT-NITRO Trial) Intracoronary nitrate testing, specifically using isosorbide dinitrate, is generally considered safe for diagnosing coronary artery spasm, as it quickly ...

4. jacc.org jacc.org/doi/10.1016/j.jacc.2018.11.040

Impact of Abnormal Coronary Reactivity on Long-Term ... On longer-term follow-up, impaired microvascular function predicts adverse cardiovascular outcomes in women with signs and symptoms of ischemia.

5. clinicaltrials.gov clinicaltrials.gov/study/NCT06896903

NCT06896903 | Analysis of Coronary Reactivity Testing ... Patients will undergo invasive assessment with CRT first without IC nitrates followed by a dose of 200-500 mcg of intracoronary nitrates and repeat CRT.

6. sciencedirect.com sciencedirect.com/science/article/pii/S0735109713058828

Provocative Testing for Coronary Reactivity and Spasm Adverse reactions to ACH include hypotension, bradycardia, dyspnea, and flushing (27). When using intracoronary (IC) ACH, the risk of bradyarrhythmia is often ...

7. ahajournals.org ahajournals.org/doi/10.1161/circulationaha.113.004096

Clinical Usefulness, Angiographic Characteristics, and ... Coronary spasm can cause myocardial ischemia and angina in patients with and those without obstructive coronary artery disease.