Angina After PCI: a Systems Medicine Study

Angina may persist or recur in patients treated by coronary angioplasty. The angioplasty involves a balloon treatment to open a blocked heart blood vessel and usually a stent (thin metal tube) is placed. Stents do not always improve symptoms and may make symptoms worse. Sometimes a drug-eluting-balloon is used instead of a stent.

This balloon coats the inside of the blood vessel to prevent re-narrowing. Research is needed to clarify the causes of ongoing angina and its impact on patients and the NHS, and to identify which patients will or will not benefit from a stent (hence avoiding over-treatment in the future).

We plan a 5-year UK-wide multicenter study involving up to 600 patients with angina undergoing coronary angioplasty (with or without a stent). They will initially have a heart MRI scan. We will assess what might influence the recurrence of angina in the year after the angioplasty procedure. We will measure small blood vessel function in the heart and the amount of plaque persisting after PCI.

Patients who report angina after coronary angioplasty usually have a second invasive angiogram. Instead, we will invite patients to have a heart MRI scan allowing us to also assess whether this scan might be more useful than a repeat angiogram in guiding clinical care. We will collaborate with life scientists, mathematicians, statisticians, and health economists to better understand causes and health economic implications of angina arising after coronary angioplasty procedures.

Background: Prior studies indicate that potentially one in three patients may experience angina within 12 months of undergoing percutaneous coronary intervention (PCI).

Hypothesis: 1) Diffuse coronary atherosclerosis and/or microvascular dysfunction impair myocardial blood flow (MBF) leading to angina post-PCI.

Design: A 5-year interdisciplinary program with 3 scientific work-packages (WPs): 1) Clinical, 2) Systems medicine, and 3) Health Economics.

WP1) Cohort study In 4 or more centers in the United Kingdom, 600 patients with angina will undergo stress/rest perfusion cardiovascular magnetic resonance (CMR) imaging with inline pixel-mapping of MBF (ml/min/g) and then coronary physiology measured during PCI. Patient reported outcome measures will be collected routinely during follow-up to 12 months.

Primary outcome: Adjudicated, residual angina (Seattle Angina Questionnaire Angina Frequency (SAQ-7-AF) score \<90).

Nested case-control study: stress perfusion CMR (MBF culprit artery territory, primary outcome) in approximately 200 patients reporting residual angina and 50 consecutive asymptomatic controls (all post-PCI). Clinically indicated coronary angiography including physiology tests (change from baseline measurement) and acetylcholine testing will be undertaken in approximately 120 patients.

WP2) Systems medicine (n=600) using biostatistics to identify multivariable baseline associates (clinical, coronary physiology, haemodynamics, circulating biomarkers (DNA, RNA, protein) of the SAQ-7-AF score (range 0 (Severe) - 100 (no angina)) post-PCI.

WP3) Health economics of NHS resource utilization and value of information (VoI) modelling to design stratified medicine trials.

Value: Identification of mechanisms to inform downstream diagnostic and therapeutic strategies for angina post-PCI.

Eligibility Criteria:
Inclusion Criteria:

BEFORE INVASIVE MANGEMENT

1. Angina by SAQ-7 Angina Frequency Score \<90\*
2. Stress CMR imaging\*

   DURING INVASIVE MANAGEMENT
3. PCI (successful)
4. Coronary physiology assessment post-PCI.

Exclusion Criteria:

1. Age \<=18 years
2. Acute MI within 30 days
3. Invasive management \>90 days after stress CMR
4. Inability to comply with the protocol
5. Lack of written informed consent.
6. Pregnancy.