Heart healthy diet - is going off your heart healthy diet one day a month ok ? example - having a nice breakfast, lunch then going out to dinner?

I do not see any problem with that. Enjoy your life, take care!

You can likely still follow a heart healthy diet when you go out to dinner. But, if you go off the diet for one meal a month you would likely be fine, as long as you did so in moderation. Eating a huge, unhealthy meal can actually result in heart issues acutely (like heart attack!) so eat in moderation, as heathy as possible to avoid an acute heart issue. Good luck!