The goal of this clinical trial is to determine if N-acetylcysteine (NAC) can reduce angina frequency in women with Angina with Non-Obstructive Coronary Arteries (ANOCA). It will also assess the impact of NAC on health status and quality of life. The main questions it aims to answer are: (i) Does NAC reduce the number of angina episodes per week? (ii) How does NAC affect quality of life and symptom burden in ANOCA patients? (iii) Does NAC reduce the need for short-acting nitrate use? Researchers will compare NAC to a placebo in a randomized, double-blind, placebo-controlled crossover study to determine its effectiveness. Participants will receive treatment with NAC 600mg twice daily for 4 weeks (28 days) and matched placebo for 4 weeks (28 days) in a computer-generated random order giving a total dosing period of 8 weeks. There will be a 2-week washout between the two treatment periods. The effectiveness of N-Acetylcysteine (NAC) will be assessed using the following measures: Angina Diary: Participants will record the frequency and severity of their angina episodes. Seattle Angina Questionnaire-7 (SAQ-7): Participants will complete this questionnaire to assess physical limitations, angina frequency, and quality of life. EuroQol 5-Dimension (EQ-5D) Questionnaire: Participants will rate their overall health and quality of life.
Background: Angina with Non-Obstructive Coronary Arteries (ANOCA) refers to a condition where patients experience chronic angina despite having no significant coronary artery blockages. This condition affects 50-70% of women undergoing elective angiography, in stark contrast to just 7-17% of men. Many experience a prolonged delay in diagnosis, resulting in notable decreases in functional capacity. NAC has been shown to reduce oxidative stress and potentiate the vasodilatory and antiaggregatory effects of nitrates, potentially reducing microvascular damage and improving myocardial perfusion, hence presenting a promising therapeutic option for ANOCA patients. Although there are no established clinical guidelines for ANOCA management, standard therapy typically includes both long-acting and short-acting nitrates to alleviate anginal symptoms. However, many ANOCA patients continue to experience symptoms despite standard therapy. As such, this trial will assess the beneficial effects of NAC therapy in ANOCA women. Primary Objectives: To determine the effect of NAC 600mg twice daily on angina frequency in patients with ANOCA who experience angina at least 3 times/week as assessed by an angina diary. Secondary Objective: The secondary objectives of this study are: i. To assess the impact of NAC therapy (600mg twice daily) on quality of life/health status, utilising generic (EQ-5D) and disease-specific (SAQ-7) health status instruments to evaluate the following PROMs: 1. Overall physical health (EQ-5D) 2. Angina frequency (SAQ-7) 3. angina-related physical limitations (SAQ-7) 4. angina-related quality of life (SAQ-7) 5. patient satisfaction with angina therapy (SAQ-7) ii. To assess the impact of NAC therapy (600mg twice daily) on angina diary measures including: a) Short-acting nitrate consumption (i.e., Glyceryl trinitrate (GTN) spray use) b) Duration of angina episodes c) Severity of angina episodes Safety objectives i. Emergency Department (ED) presentations with Chest pain ii. Hospital admissions with chest pain iii. Major Adverse Coronary Events (MACE) Clinic Assessments: Visit 1: Screening: Screening assessments will be completed within 14 days prior to administration of NAC/Placebo. * Consent to participate * Baseline safety bloods (complete blood examination, electrolytes, liver \& kidney functions tests, high sensitivity C-reactive protein, ionised calcium) * Physical Examination * Vital assessments * Electrocardiogram (ECG) assessment Week 1 \& 2 * Angina Diary Visit 2: Weeks 3-6: Phase 1 study medication period * Angina Diary * Health-related questionnaires (SAQ-7, EQ-5D) Visit 3: End of Phase 1 visit * Angina Diary * Health-related questionnaires (SAQ-7, EQ-5D) Weeks 7\& 8 Wash out Period * Angina Diary Visit 4: Weeks 9-12 Phase 2 study medication period * Angina Diary * Health-related questionnaires (SAQ-7, EQ-5D) Visit 5: End of Phase 2 visit * Health-related questionnaires (SAQ-7, EQ-5D) Weeks 4,10 \& 14 Follow up Phone Contact Duration of Therapy: Patients will receive treatment with NAC 600mg twice daily for 4 weeks (28 days) and matched placebo for 4 weeks (28 days) in a computer-generated random order (double-blind, crossover design) giving a total dosing period of 8 weeks. There will be a 2-week (14 day) washout between the two treatment periods. Criteria for Evaluation: Angina diary: Results will be considered significant if participants have significantly (p\<0.05) reduced features of angina extracted from angina diary during the NAC phase compared to placebo phase. SAQ-7: Results will be considered significant if participants demonstrate reduced physical limitations \& angina frequency and improved quality of life during NAC phase compared to placebo phase. EQ-5D: Results will be considered significant if participants demonstrate improved quality of life scores during NAC Phase compared to placebo phase. Statistical Methods: Efficacy Endpoint NAC's anti-anginal efficacy will be undertaken by blinded analysis of the angina diary endpoints and other endpoints. The comparison between patients with respect to treatment order will be analysed utilising a linear mixed-effects model. Safety Endpoint Frequency and severity of adverse events.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
25
The investigational product for this study is NAC 600 mg capsules. The NAC drug substance is sourced from a Good Manufacturing Practice (GMP)-certified supplier by Syntro Health Pty Ltd and tested on receipt
To ensure appropriate blinding and to match the physical characteristics of the NAC capsules, the placebo capsules will be filled with dicalcium phosphate (DCP). DCP has been selected over microcrystalline cellulose due to the weight requirements of the NAC formulation.
The Queen Elizabeth Hospital
Adelaide, South Australia, Australia
Frequency of angina episodes recorded in angina diary.
Number of angina episodes recorded in angina diary. The angina diary is developed to record the frequency, duration, severity, and reliever of chest pain episodes. Participant record their angina episodes throughout the study period.
Time frame: 8 weeks (4 weeks of NAC treatment and 4 weeks of placebo treatment)
Frequency of Short-acting nitrate consumption (i.e., Glyceryl trinitrate (GTN) spray use)
Short-acting nitrate consumption (i.e., Glyceryl trinitrate (GTN) spray use), self reported on angina diary
Time frame: 8 weeks (4 weeks treatment compared to 4 weeks placebo)
Frequency of prolonged angina episodes (ie episodes persisting > 20 minutes)
Frequency of prolonged angina episodes (ie episodes persisting \> 20 minutes) assessed from patient's self reported angina diary
Time frame: 8 weeks (4 weeks of NAC treatment and 4 weeks of placebo treatment)
Angina frequency score as assessed by Seattle Angina Questionnaire (SAQ)
The Seattle Angina Questionnaire (SAQ) is a tool used to assess the health-related quality of life in patients with angina, especially those with coronary artery disease (CAD). Patients report the frequency of their angina episodes, including both exertional and spontaneous chest pain, based on structured response options. The score is then converted to a 0-100 scale, with higher scores indicating less frequent angina and better symptom control.
Time frame: End of Phase 1 (Score at the end of 4 weeks) & End of Phase 2 ( Score at the end of 4 weeks)
Angina-related physical limitations score as assessed on Seattle Angina Questionnaire
The Angina-Related Physical Limitations Score is a subscale of the Seattle Angina Questionnaire (SAQ) that evaluates the extent to which angina symptoms restrict a patient's ability to perform daily physical activities. Patients rate the difficulty they experience in performing activities such as walking, climbing stairs, or carrying groceries due to their angina. Responses are scored on a 0-100 scale, where higher scores indicate fewer physical limitations and better functional status.
Time frame: End of Phase 1 (Score at the end of 4 weeks) & End of Phase 2 ( Score at the end of 4 weeks)
Angina-related quality of life score as assessed on Seattle Angina Questionnaire
Patients assess the impact of angina on their overall quality of life, including emotional well-being, physical limitations, and social functioning. The score is converted to a 0-100 scale, with higher scores reflecting better quality of life and less impact from angina.
Time frame: End of Phase 1 (Score at the end of 4 weeks) & End of Phase 2 ( Score at the end of 4 weeks)
Patient satisfaction with angina therapy score as assessed on Seattle Angina Questionnaire
Patients rate their satisfaction with the current treatment regimen for managing angina, based on structured questions related to the effectiveness, convenience, and side effects of therapy. The score is converted to a 0-100 scale, with higher scores indicating greater satisfaction.
Time frame: End of Phase 1 (Score at the end of 4 weeks) & End of Phase 2 ( Score at the end of 4 weeks)
Overall physical health as assessed by EQ-5D Questionnaire
EQ-5D is a standardized questionnaire developed by the EuroQol Group to measure health-related quality of life. Patients assess their overall physical health through the EQ-5D, which includes questions related to mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The score is then converted to a 0-100 scale, with higher scores indicating better overall physical health and less impact from the condition.
Time frame: End of Phase 1 (Score at the end of 4 weeks) & End of Phase 2 ( Score at the end of 4 weeks)
Severity score of angina episodes as assessed on angina diary
Angina severity score (scored as 1-10), 10 being most intense assessed from patient's self-reported angina diary
Time frame: 8 weeks (4 weeks of NAC treatment and 4 weeks of placebo treatment)
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