Less than a minute in most cases!
And yes, you can have a heart attack with no permanent damage. Even if the victum does go unconscious, there is a chance of complete recovery. Along with CPR there are medications out there that are actually targeted to achieve a positive result if given within a short amount of time from the onset of symptoms.
I have had an instance where my heart suddenly stopped. I felt like I was about to black out. I quickly hit my chest as hard as I could and it started beating again, and the symptoms went away. I have been checked for a heart arythmia as well as an echocardiogram. Nothing was found. Could I have actually had a sudden cardiac arrest that I somehow recovered from?
For heart issues, I can not say enough good things about the herb hawthorn. Look into it. It is safe and will not interfere with meds. It is a heart tonic and strengthener among other things. It works on people as well as animals. It does not cure, so it only helps as long as you are taking it, which should be forever if you have a weak heart. It will make a huge difference in how you feel and may just stop you from having heart attacks altogether. Do the research. Check it out for yourself. I've seen it work for many. They always end up dying from something else, not heart failure (the elderly).
Anything is possible, although if you were that close to passing out you most likely would not have the strength to hit you chest hard enough to make a difference. I would re-address this issue with your physician. Sometimes people with arrythmias don't have them all the time. a 48 hour holter monitor is recommended.
Have you had your thyroid checked?
Although alternative treatments can be good for some, never begin taking them without first notifying your physician. They can also do more harm than good. Until herbs and others treatments have gone through traditional clinical trials, no one can guarentee the safety and efficacy profile.
In the case of Hawthorn, no research has been done to date. In fact I'm not sure how it can claim to improve "heart attacks" and "heart Failure". Both are entirely different etiologies.
Please... in the case of serious ailments such as cardiac, cancer etc., always consult your physician before taking anything, whether it be herbal, mineral, over the counter or prescription. You could be asking for more troubles than you already have.
The answer is "it depends". People have been shot through the heart and remained conscious enough to return fire for at least half a minute.
As for the so-called "pre-cordial thump", it is useful only when the heart stops due to what is called ventricular fibrillation. This doesn't exactly "reset" the heart. It returns control of the heart to the atrial pacemaker. In this case a "thump" to the sternum within thirty seconds has a high probability of converting the v-fib into a rhythym more compatible with life (a sinus rhythym). The longer the time interval, the more electrical stimulus necessary. After 45 seconds a defibrillator is generally required.
For a long time, in a "witnessed" cardiac arrest, a blow to the chest was the first action recommended.
I agree that it would be a good idea to talk to your doctor first. I also agree that caution needs to be taken with herbs in general. However, I still hold to my feelings on this particular herb. It is one of the safest out there. This and red raspberry leaves for women who want to get pregnant or are pregnant are my two all time favorites and far as safety and results when used correctly. If you had ever seen so many drastic improvements on as many people and animals as I have, you would see things through my eyes. I can only share through my own experiences and observations. I've to yet even seen this herb to affect anyone in a negative way. There is always risk in anything, including especially prescription meds. This is not just book knowledge, this is seeing dramatic results over and over. I'm not going to get into scientific research, etc. That is the work the user needs to do before they make up their mind to use it. Whatever, the heart ailment, as long as it can use something to strengthen it in some way, this is the way to go. It will not interfere with medications.
I understand your concerns and I'm glad you brought them up so that Tyler 85 or anyone else can look into all sides and be as well informed as possible. Also, I am not saying that it is a substitute for other care either. It would be a compliment to it. Like I said, it doesn't cure it only strengthens.