In people living with coronary heart disease (CHD), V̇O2 peak predicts all-cause mortality. V̇O2 peak increases with regular exercise training. Thus, in exercise-based cardiovascular rehabilitation programmes, V̇O2 peak is a useful marker of how effective the exercise training has been.

Maximal cardiopulmonary exercise testing (CPET) is the gold standard method of measuring V̇O2 peak. However, maximal CPET is expensive and requires trained staff to conduct the test and interpret the results. Furthermore, CPET is not routinely available in United Kingdom (UK) cardiovascular rehabilitation programmes. Field exercise tests, such as incremental cycle ergometer tests, are used in conjunction with predictive equations to estimate V̇O2 peak. However, this group has shown that estimating changes in V̇O2 peak in this way is inaccurate. Alternative solutions are required.

VentriJect Seismofit® uses a technique called seismocardiography (SCG); the measurement of vibrations in the chest wall, caused by each heartbeat, using accelerometers. SCG can be used to estimate V̇O2 peak from a SCG measurement taken at rest. This study will explore the validity of VentriJect Seismofit for estimating V̇O2 peak in people with CHD.

Inclusion Criteria:

• Stable coronary heart disease
• Able to lay fully supine for five minutes
• Capable of performing a maximum effort CPET on a stationary cycle ergometer
• Currently enrolled in a Phase IV cardiac rehabilitation programme
• A minimum of 12 weeks after a cardiac event

Exclusion Criteria:

• Awaiting any significant medical investigations relating to CPET absolute contraindications
• Hospitalisation within the last 4 weeks relating to CPET absolute contraindications
• Implantable cardiac devices e.g. pacemaker or implantable cardioverter defibrillator
• Unstable angina
• Unstable diabetes
• Left main coronary stenosis or its equivalent
• Known third degree heart block
• Unstable heart failure/New York Heart Association (NYHA) III or IV Heart Failure
• Acute aortic dissection, myocarditis, or pericarditis/endocarditis
• Suspected or known dissecting aneurysm
• Symptomatic severe aortic stenosis
• Acute deep vein thrombosis, pulmonary embolism or pulmonary infection
• Uncontrolled asthma
• Pulmonary oedema
• Respiratory failure
• Ambient O2 desaturation at rest <85%
• Resting tachycardia (>100bpm)
• Currently in atrial fibrillation
• Uncontrolled arrhythmia
• Resting systolic blood pressure >180 mmHg
• Resting diastolic blood pressure >100 mmHg
• Other conditions that prevent participants from completing study investigations (e.g. recent (last ~6 months) cardiac arrest)

Adults with coronary heart disease currently enrolled in a Phase IV cardiac rehabilitation programme