polo vasquez,

Thanks for your question.  It's difficult to answer your question with any certainty.  It is not unusual for most people to feel a "skipped beat" occasionally.  This sensation is known as palpitations and could be caused by any one of a number of things.  The most common are early beats, either from the small chamber, called a premature atrial contraction (PAC), or from the larger chambers, called a premature ventricular beat (PVC).  In most situations, they are self limited and pose no problem, or indicate a greater risk for more serious heart disease.  Their incidence tends to go up with stimulants like caffeine.

Other causes include cardiac arrhythmias like atrial fibrillation which is an irregular rhythm  originating in the small chamber atrium), supraventricular tachycardia which is a fast heart beat also originating from the atria, and a few other less common ones.

The advice for most people is: if these palpitations are very frequent and concerning, you should make an appointment with your doctor and have him examine you, as well as perform an electrocardiogram to see what the problem is, is any.  In some cases, he/she may request and 24 hour monitor of your heart called a Holter Monitor, in order to "catch" the abnormal rhythm, which may be missed on the standard electrocardiogram. 

In your particular instance, because of your prior cardiac history, you should contact your physician for an appointment and evaluation.  Patients with heart disease should be on the lookout for a recurrence of their prior symptoms, or any new symptoms that they may be experiencing, as this might indicate a problem.  Again, most likely, it will prove to be nothing serious, but you should have it checked out to be sure.

I hope this has been helpful.

Martin Cane, M.D.