A heart attack is called "ischemia", not "Myocarditis". They are functionally different things, with different causes. This Tweet is making a misleading connection between the two, let alone lacking other relevant medical information about the poster. Anecdotal at best.

Roughly 3.1 million people get myocarditis every year according to Mayo Clinic. So far the number of cases close in timing to vaccinations is adequately explained by coincidence. Conversely, the link between COVID-19 and serious heart conditions is extremely clear.

Yesterday, I had a heart attack My cardiovascular system is completely normal & healthy But last week I took the Pfizer vaccine and there are reports that it’s been causing heart complications Most causes have been ruled out and it looks like Pfizer may have done this to me...