Could Skipping Of Heart Beat Be Due To Anxiety Attack?

About 3-4 times per day I have a feeling of anxiousness and actually skip a heart beat or a run of 5 or so beats. I have a genetic background in heart disease from my father. Since my husband passed 3 years ago I have been taking Zoloft 50mg along with Xanax 0.5mg at night only. My family practice physician increased the Zoloft to 100mg about 3 weeks ago. Any suggestion that this could be a heart issue, or perhaps anxiety episodes. Thank you very much