Your heart rate is fine while working out. Your max predicted heart rate is calculated as 220 - your age which is 204 for you so no worries. As far as a heart attack from a blood clot, it is very rare and even more so at your age, don't worry about things like heart attacks, enjoy life.
200 bpm is high but a healthy heart in a young man should handle that just fine, as Jon told you.
That said, you don't need to stay at 200 bpm to get effect from your exercise. Most people are not able to sustain that heavy exercise for a long time, maybe just a few minutes. I would say it's better to stay at a lower percentage of max (in your case, without knowing your resting heart rate, maybe 160-180 bpm) for half an hour or more. That would probably give better results :)
But all exercise is great! Just keep in mind that when you work out at max intensity, warm-up is essential.
This site complies with the HONcode standard for trustworthy health information.
The Content on this Site is presented in a summary fashion, and is intended to be used for educational and entertainment purposes only. It is not intended to be and should not be interpreted as medical advice or a diagnosis of any health or fitness problem, condition or disease; or a recommendation for a specific test, doctor, care provider, procedure, treatment plan, product, or course of action. Med Help International, Inc. is not a medical or healthcare provider and your use of this Site does not create a doctor / patient relationship. We disclaim all responsibility for the professional qualifications and licensing of, and services provided by, any physician or other health providers posting on or otherwise referred to on this Site and/or any Third Party Site. Never disregard the medical advice of your physician or health professional, or delay in seeking such advice, because of something you read on this Site. We offer this Site AS IS and without any warranties. By using this Site you agree to the following Terms and Conditions. If you think you may have a medical emergency, call your physician or 911 immediately.