For me, it is understandable why you are reacting the way you do . . . but . . . if a cardiologist believes that the condition is not life threatening, I would suggest that you discuss with him/her what the potential symptoms might be so you will have a baseline to help you manage that aspect of anxiety and why your condition is not life threatening . . . then, I would still suggest working with a therapist . . . sometimes when I have this happen to me, I have a difficult time in re-centering myself because my mind has already, if you will, prepared my body with anxiety . . . then, I have to undo the heightened level of anticipation . . . an appropriate counselor (not a psychiatrist) but a counselor can help you reframe the anxiety . . .
I am not criticizing your parents, but I do not think you are a hypochondriac . . . it is sometimes difficult, even with the best intentions, for folks who have not experienced ongoing anxiety to fully understand the cumulative effects of unresolved anxiety . . . it seems, from my experience, and given your uncle's death, that you are working to process anxiety . . . you have to remember that your uncle's death has affected your parents also and they may be trying to cope with their own grieving process while at the same time supporting you . . . so, they may be focusing more on the cardiologist's telling them that there is no danger and that is a sense of relief to them, but, at the same time your perspective is now having to manage anxiety . . . you appear to have a solid mind set because you recognize how your parents might be seeing your reality even though they cannot really appreciate the impact on you of the anxiety . . . this is good because you will not feel isolated . . . keep the conversation going with them . . .
In other words, even though they may use the term hypochondriac, etc., it could be their coping strategy . . . yours might include, though, working with a counselor and, of course, coming back here any time you feel like joining the discussion . . .take care, kc