Aerobic high-intensity interval exercise training in patients with angina and no obstructive coronary artery disease: feasibility and physiological effects
Question
Can a structured 12-week aerobic high-intensity interval training program be feasible in patients with angina and no obstructive coronary artery disease, and does it affect physiological mechanisms related to symptoms, including coronary flow velocity reserve, endothelial function, and functional capacity?
Summary
This open-label pilot study tested whether 12 weeks of supervised aerobic high-intensity interval training was feasible for patients with angina and no obstructive coronary artery disease. Sixteen trained patients completed treadmill HIIT three times weekly and four similar patients served as non-randomized controls. Training attendance averaged 82.3%, no training-related adverse events were reported beyond expected angina and fatigue, and the HIIT group improved peak VO2, flow-mediated dilation, nitroglycerine-mediated dilation, and coronary flow velocity reserve.
Methodology
- Adults with effort angina and no obstructive coronary artery disease on invasive coronary angiography.
- 20 participants.
- Treadmill.
- Work intervals: 4 minutes at 80-90% maximal heart rate.
- Recovery: 3 minutes active recovery at 60-70% maximal heart rate.
- Intensity: 80-90% maximal heart rate during intervals.
- At least 35 minutes excluding any unreported cooldown.
- 3 sessions per week.
- 12 weeks.
- Open-label, non-randomized prospective mechanistic pilot trial with a 4:1 intervention-to-control ratio.
- Coronary flow velocity reserve, Flow-mediated vasodilation, Peak VO2, and Training attendance and adverse events were tracked.
Outcomes
Attendance
Average attendance to HIT sessions was 82.3% +/- 10.1, range 56-94.
Peak VO2
Peak VO2 increased in the HIT group from 28.75 +/- 6.51 to 31.93 +/- 6.46 mL/kg/min; controls changed from 26.52 +/- 4.10 to 27.17 +/- 3.51.
HIT within-group P < 0.001; control P = 0.250; between-group P = 0.022.
CFVR
CFVR increased in the HIT group from 2.50 +/- 0.48 to 3.04 +/- 0.71; control changed from 2.43 +/- 0.59 to 2.74 +/- 0.48.
HIT within-group P < 0.001; control P = 0.625; between-group P = 0.211.
FMD relative change
FMD relative change increased in HIT from 4.19 +/- 2.42% to 8.28 +/- 2.85%; controls changed from 4.32 +/- 2.17% to 4.62 +/- 2.13%.
HIT within-group P < 0.001; control P = 0.875; between-group P = 0.005.
Adverse events
No adverse events related to aerobic HIT were reported other than expected angina and fatigue.
Insights
- A cardiac rehabilitation-style 4x4 treadmill HIIT protocol can be feasible for selected ANOCA patients when supervised and heart-rate monitored.
- For clinical populations with chest pain, the source evidence supports monitored and screened exercise contexts, not unsupervised high-intensity consumer recommendations.
- The study provides reusable protocol details for 4-min aerobic intervals but should be treated as pilot evidence.
Limitations
- Small sample with only 20 analyzed participants and four controls.
- Open-label, non-randomized design.
- Controls were selected because they lived too far away to train, which may introduce selection bias.
- Lack of adequate blinding for interpretation of measurements.
- No direct evaluation of relationship between physiological changes and angina severity.
- Supervised clinical setting limits translation to consumer home workouts.
Safety
- No HIT-related adverse events reported other than expected angina and fatigue.
- Two HIT-assigned patients quit because of health problems unrelated to exercise training.