It is excellent that your partner is trying to quit smoking, and it is equally excellent that you are supporting his push to stop.
Stopping smoking is hard but it can be done. Normally we tackle this on multiple levels.
Through your cardiologist or family doctor, your partner can be referred to counseling services. Nicotine replacement therapy has been very helpful for many people- your partner can try gum, lozenges or patches.
Some medications like Varenicline (Chantix) and Bupropion (Zyban) may be useful but need to be discussed with your cardiologist to ensure that they are appropriate given your partner’s medical history.
The Centers for Disease Control and Prevention (CDC) also provides an online resource that many ex-smokers find useful and hopefully this also helps. Have a look http://www.smokefree.gov/
I would seek his Doctors help on this. Yes there is no smoke with harmful particles using electric cigarettes, but you still receive Nicotine. This chemical hits the Brain in less than 10 seconds and starts all kinds of chemical reactions. Heart rates increases, blood pressure increases, sugars are released into the blood to name but a few. I think his Doctor would need to help with the addiction. There are 2 types of addiction. 1) those who smoke through habits, initiated by triggers such as drinking, eating or socializing. 2) those who are addicted strongly to the nicotine. The second is much harder to kick. I was one of those and yes it got harder every single day. I used to have a sweet cup of tea each time I wanted a cigarette, so at least I had the sugar boost. After 3 weeks, the cold turkey stopped. I still sometimes see someone smoking and think "mmmm, that looks really good", BUT it's so easy to tell myself not to be stupid now. Using electric cigarettes, nicotine patches etc are pointless in my opinion. You get addicted to those instead and have to try and ween off them. I've seen friends wearing patches AND smoking, and I've seen people with those electric cigarettes in their mouths 24/7. I tried acupuncture, hypnosis and a whole variety of things, nothing worked except will power. It's actually good because it gives you a stronger mind at the end of the day. If you can kick the cigs, you can kick anything. Lots of encouragement helps too. My kids used to tell me every day how well I was doing, even though I was really grumpy. I would say at around 9 days he will reach his peak, and really be climbing the walls, but after that it gradually gets easier. After 21 days I hardly thought about cigarettes. I also drank lots of fresh orange juice which seemed to help. Smokers seem to be more deficient in vitamin C and when those levels raise to normal, you feel much healthier. But seek his Doctors help, there are usually counselling groups where people in the same position go and chat to each other.