Im a former drug addict in recovery for the last 3 years & I've been plagued with heart palpitations and arrhythmias since i was about 18. Im now 31. Most likely from smoking and heavy drug use. since i stoped smoking started vaping about 10 months ago, the arrhythmias have decreased dramatically! I've had EKG's and recently had a huge batch of cardiac and circulation tests done, all showing no visible problems. I'm pretty much a 36mg nic user, but i was a two pack a day smoker for prolly half of the 17 years i smoked. It still happens from time to time but i feel like the severity and frequency of them has decreased at leaste 80% if not more. But when they do still happen I've noticed its at times when i have heavy congestion in my chest and lungs and when i clear my lungs they subside. so, It's always a possibility that it has more to do with vapor(liquid in your lungs), then the nic or the chemicals.... im no expert, but i just thought id share my experiences to offer you another possibility. anything that causes your heart to act funny, you should stop until you get to the bottom of it!