The scary beats are almost certainly PACs, or 'premature atrial complexes'. What they are is a missed beat, but the heart compensates with an extra beat in the next rhythm cycle, and the first of those two successive beats is a doozy because the heart has filled with blood in a way it doesn't during normal rhythm...so you get a strong 'hydraulic' boost that courses up your aorta and beyond.

PACs are benign, mostly, and cardiologists and electrophysiologists are loath to do anything about them. Instead, they WILL, or SHOULD, attempt to allay one's fears and to manage symptoms, which are the two worst things about PACs. However, when PACs come so often, which is usually the evolution of most/all cardiac arrhythmias, their total numbers present what is called a 'burden' that might be excessive. Further, PACs do have a negative impact on mortality; a burden higher than 3% for more than months or a couple of years is predictive of an earlier death than might otherwise be the case for the same patient with a healthy heart free of arrythmia. (I hope that makes sense). Note that there is a lot of variation between patients due to other factors such as the presence of other comorbidities, overall health and heart condition, age, and genetic factors, so don't go running off fearful that you're headed to an early grave. Our hearts are robust organs that can take some abuse, and they'll often return to their natural size and morphology after successful treatment.

I do urge you to consider seeing a more sympathetic and determined/open-minded cardiologist because you do need an accurate measure of your PAC burden (I'm assuming I'm correct, but really I'm not a health professional and am only guessing that what you are experiencing are PACs).