Prospective Evaluation Of Exercise-Induced Cardiac Conduction Instability In Predicting Ventricular Fibrillation Events In Hypertrophic Cardiomyopathy

You might be able to take part in this study if you're an adult aged 18 to 100 years old and have a confirmed diagnosis of Hypertrophic Cardiomyopathy (HCM). Generally, for HCM, this means your heart muscle is thicker than usual (for example, 15mm or more), or if your heart muscle is slightly less thick (over 13mm) but you also have a close relative with HCM and other signs of heart changes.

Crucially, you would need to be considered at either intermediate or high risk of having a dangerously fast heartbeat in the next five years, based on your current medical assessment by doctors specialising in inherited heart conditions at a London clinic or another participating hospital.

However, you wouldn't be able to join the study if you've had a previous cardiac arrest (your heart stopped) or a life-threatening fast heartbeat that needed urgent medical help. You're also excluded if you have other specific health conditions that cause heart thickening, such as very high blood pressure or certain rare genetic conditions. If you already have an ICD that has previously delivered a shock because of a dangerous heart rhythm, or if you can't safely stop taking certain heart medications (beta-blockers) for the test, or if you have severe movement limitations preventing exercise, you wouldn't be able to participate. Pregnant individuals, or those planning pregnancy at the time of the CT scan, and anyone with skin allergies to ECG gel would also not be suitable for the study.

If you decide to join the study, you'll first have a chat with the research team at your clinic to make sure you understand everything and give your permission. You can ask any questions you have during this time. Your decision to join or leave the study won't affect how your doctors care for you.

The main part of the study involves spending about half a day at a hospital unit that specialises in heart tests. During this half-day, you'll:

1. Have any last questions answered and confirm your permission to participate. 2. Have a special vest, which looks like a waistcoat, put on. This vest has sensors that attach to your skin with a conductive gel to record your heart's electrical activity. 3. Undergo a quick, low-dose CT scan of your chest. This scan helps to accurately map your heart's position relative to the sensors on the vest. The radiation exposure is very small, similar to what you'd naturally get over about six months. 4. Walk or run on a treadmill while wearing the vest. The vest will record your heart's electrical signals during this exercise. 5. Repeat the V-CoS test while performing a 'Valsalva manoeuvre'. What this means is you’ll be asked to try and breathe out forcefully, as if you're blowing up a balloon, but without actually letting air out of your mouth or nose.

If you have a pacemaker or defibrillator already implanted, there might be an additional test where your device is used to create extra heartbeats while the vest records the signals. The study will involve a follow-up period of up to 5 years, during which your doctors will continue to monitor your health. The total duration of active patient participation would be the half-day testing, plus regular follow-up to monitor your health over 5 years.