elevated heart enzymes

My husband went to the hospital this weekend for chest pain, shortness of breath and dizziness. EKG came back fine so they took some blood. They then told us that his blood test results said his heart enzyme level was 1.9 and he probably has a mild heart attack and there was some damage to his heart. They told us they were putting him in the ICU and hooked him up to a couple iv's with medications. Three hours later they re did the blood test and this time it came back 0.06. They stopped the iv's and all medications and told us that he did not have a heart attack and there was no heart damage. He is 38 years old, a smoker, and never had heart or blood pressure problems in the past. Why would his heart enzyme level be so high and than 3 hours later it is fine? We are very concerned.