I agree with cbg, he'd be very hard pressed to tie the heart attack in to worker's comp. Only in the rarest of circumstances, such as that his type of work or working conditions could be said to have been a direct cause, ( something very strenuous required, extreme temperatures that particular day) something of that sort. I do not know if Nevada has a short term disability program for workers in their state, but if they don't, and your employer has no such programs, you are out of luck as far as income support for those weeks you are off due to the heart attack, (as you are in most of the southeastern states without state disability programs.) You may qualify for FMLA, depending on the size of your employer and how long you have been with them, and that will protect your job for you until you can get back to work, maintains your health insurance if it was through the job, but that's about it.
You will not be able to receive unemployment benefits during any time you are out of work due to a medical condition. If your employer were to terminate you when your FMLA runs out, or if you have no eligibility for FMLA, sign up for unemployment immediately, and you could begin receiving unemployment insurance when you are fully released to return to work.