I had heart failure last year August, same symptoms as yours. The hospital made me undergo angiogram. No plaque was there so it was somewhat a waste of money. I have been worried since. I had ECG, Cardiac MRI and with meds, the last of which was July this year. But up to now I am still afraid my heart will stop, when 2 cardios told me my heart is strong. My bp and cholesterol and blood sugar is good October...I think I will die of anxiety rather than my condition.. so please do as advised, by people here, have a hobby and distract yourself from worry. The pain from left side might be acid reflux only or heartburn