The goal of this observational study is to learn about the factors which determine how well ventricular tachycardia (VT) is tolerated. The main questions it aims to answer are: 1. What impact does coronary artery disease have on the ability for a patient to tolerate VT? 2. Does treatment of coronary artery disease with stents improve the tolerability of VT? Participants who are undergoing a clinically indicated coronary angiogram or coronary angioplasty procedure will have measurements of blood pressure, coronary pressure and coronary flow made during pacing at a range of heart rates.