@Clouise I had exactly the same issues with racing heart & breathlessness at the slightest effort, especially after my last round of chemo. I found it alarming to say the least. I'd gone from vigorously walking 6 - 8kms in a very hilly area to having to sit down repeatedly on a short and slow stroll, in a matter of three months. They have mostly resolved (and yes, just with time) but I found the easy dismissal by the medicos upsetting. We're taught to be alert and alarmed at heart attack symptoms. I definitely required more knowledge and reassurance on this front.