Here is a thread on what people with heart disease should consider before taking vaccine 1/n
People with heart disease are at increased risk from COVID19 not only due to heart disease but also from diabetes & hypertension. Thus benefits of vaccination are greater. Now the nuance https://twitter.com/serioustaurean/status/1352473379467534337

Reports of sudden deaths following vaccination have received widespread coverage, mostly in the old (Norway) as well as young (Karnataka, India & Portugal) attributed to Cardiac events. This has to be seen against millions vaccinated. Risk of COVID19 death above 70 is 14% 2/n

One can say a particular mode of death is attributable (partially or fully) to vaccination if it is raised above the baseline risk. Even still benefits of vaccine outweighs risk.
Let's discuss whether vaccine can plausibly trigger cardiac events in high risk individuals 3/n

Phase III Trials can still miss rare adverse events as Trials are typically conducted in healthy populations making it necessary to have surveillance in place during large scale vaccine roll-out. Creating a registry of subjects before administration of vaccine helps with baseline