I Was Diagnosed With Cardiomyopathy 2 Years Ago, But Still

I was diagnosed with cardiomyopathy 2 years ago, but still have no symptoms. My blood pressure has always been under 120/80 even before this, but my cardiologist put me on a low dose of metroprolol succinate once a day. Recently, I had constipation, several times and strained hard to go. Since that time my blood pressure has increased to over 120 to 130 / 75. Could I have damaged my heart with the straining?