Don't you just love secretaries?! Your cardiologist is the one to listen to, he has the training and expertise after all!
A little knowledge can be a dangerous thing. Like ltigo said, listen to the cardiologist.
If you start having multiple PvC's in a row, it is called Ventricular Tachycardia. Now some people have V-Tach for a few seconds are maybe a little longer and it goes away and you go back to sinus rhythm. However, if your heart does not go back into normal rhythm, V-Tach can lead to the deadly ventricular rhythm called Ventricular Fibrillation. If you do not receive immediate medical attention (CPR, De fibrillation) this rhythm is always fatal. Your heart shakes and moves around like a bag of worms instead of beating. Most of the time, with a structurally normal heart, no heart disease or blockage, V-Tach will not happen. That is what your doctor is trying to say. The secretary is trying to say PvC's in a row can cause V-Tach which in turn can cause V-Fib.