Doctors currently decide whether to stent a narrowed heart artery based on a 20% pressure drop—but no one knows if that threshold actually triggers a patient’s chest pain. This study will directly test, for the first time, exactly how much blood-flow restriction is needed to cause angina in each individual narrowing. The problem is that many patients have multiple narrowings, and the same pressure drop may not produce the same symptom in different people—or even in different spots in the same artery. Current guidelines treat all narrowings alike, which may leave some people with persistent pain after stenting. Researchers will recruit 60 patients with two discrete narrowings. During angiography, they will stent one narrowing, then gradually re-narrow it with a small balloon while the patient pedals on a stationary bike. When angina begins, a pressure wire measures the exact reduction. They repeat the process for the second narrowing. If successful, this work could transform how cardiologists personalise stenting decisions—moving from a one-size-fits-all pressure threshold to lesion-specific, symptom-driven treatment. That would mean fewer unnecessary stents and better relief for patients whose angina currently persists after intervention.
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Background Coronary artery stenoses are narrowings in the vessels supplying oxygenated blood to the heart muscle, which can result in the symptom of angina. Angina typically presents as chest pain brought on with exercise, and can significantly limit a person’s ability to perform their daily activities and impair quality of life. A coronary angiogram is a procedure that can diagnose and treat these narrowings. During an angiogram, a wire is passed into the coronary artery to measure a pressure gradient to determine how severe the narrowing is. When the pressure across a narrowing is reduced by 20% or more, current guidelines recommend the insertion of a stent to restore normal flow and relieve symptoms. We do not actually know if a 20% pressure reduction is the level that causes angina. Additionally, many people have more than one narrowing. We do not know whether the amount of pressure reduction that causes angina is different between different people, or even different between different narrowings in the same person. Objective To measure the pressure reduction required to cause angina for each coronary artery narrowing, in individuals with 2 discrete narrowings. Method 60 participants who have had a computed tomography coronary angiography demonstrating 2 coronary stenoses suitable for stenting will be recruited. Two weeks prior to angiography, all participants will have symptom assessment using questionnaires, a smartphone application and a wearable activity tracker. During angiography, the order in which to treat and test each coronary stenosis will be randomly assigned. The first stenosis will be treated with a stent to restore normal blood flow. The patient will then pedal on a supine bicycle attached to the catheterisation laboratory table, and a small balloon will be gradually inflated inside the stent to re-introduce narrowing. At the point when angina develops, a special wire will be used to measure the pressure reduction across the balloon. The patient will rest, and the second stenosis will be treated. The experimental protocol with balloon inflation during supine exercise will be repeated for the second narrowing. Importance The results of this study will improve our current understanding of the relationship coronary flow reduction and symptoms. This will enable future cardiologists to tailor the management strategy for patients with angina and improve symptom relief success from stenting.
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