This petition for review was brought by Mildred Fargen, widow of Gilbert H. Far-gen, to vacate the memorandum decision of the Court of Appeals, No. 1 CA-IC 2050, filed June 7, 1979. We accepted review. See A.R.S. § 12-120.24 and Rule 23, Rules of Civil Appellate Procedure, 17A A.R.S. Award of the Industrial Commission set aside.
Gilbert H. Fargen and his wife, Mildred Fargen, were employed as co-managers of the Bell Road Mini Storage. Their job included some light maintenance work. Occasionally Gilbert Fargen was called upon to remove and replace corrugated metal partitions from between lockers. Each corrugated metal sheet weighed eleven pounds and just prior to Gilbert Fargen’s death he had been moving these corrugated metal sheets, two at a time.
Mildred Fargen filed a compensation claim for death benefits, which was denied by the carrier, and a formal hearing was held. The hearing officer found that Gilbert Fargen’s death was causally related to his employment, and entered an award for death benefits. The employer brought a petition for review in the Court of Appeals, which court set aside the award in a memorandum decision, concluding after examination of the evidence that the record did not support the conclusion that Gilbert Fargen’s death was causally related to his employment. We granted Mildred Fargen’s petition for review of the decision of the Court of Appeals.
Nearly twenty-five years ago, in Phelps Dodge Corporation v. Cabarga, 79 Ariz. 148, 285 P.2d 605 (1955), we held that where the usual exertion of employment precipitates a heart attack it is compensable under the Workmen’s Compensation Act of this State. We also held that the exertion, whether usual or unusual, must be of such a character that the injury can be traced to it with reasonable assurance that the work caused or contributed to the injury, saying:
“There must be a recognizable, causal connection. The requirements of the statute will not be fulfilled merely because the employee dies on the job while doing some causal or physically inconsequential thing * * * ”
Other than the death certificate, which stated the cause of death as being “acute coronary insufficiency”, the only testimony relative thereto was given by Paul M. Bindelglas, M.D., a psychiatrist. He had treated Gilbert Fargen for an unrelated emotional problem in May of 1977. At that time an EKG revealed a “right bundle branch block”, seemingly an abnormality of the heart arterial system. An extensive hypothetical question was posed to Dr. Bindelglas:
*495“Q. * * * Doctor, based on the medical data that you have here, your treatment and examination of this patient at Camelback Hospital, do you have an opinion within a reasonable degree of medical certainty or probability based upon your medical education, your experiences, your treatment of Mr. Fargen, as to whether the conditions you’ve set forth were sufficient to aggravate, precipitate or hasten his underlying or coronary problem to an acute coronary insufficiency, which ultimately resulted in his death? Do you have an opinion?”
Dr. Bindelglas testified that he did have an opinion and that:
“ * * * Now, I don’t know what the final diagnosis was, whether it was another acute coronary, whether it was in the same area, but just dealing within that general way on a hypothetical, it is possible it could have contributed.”
Counsel then stated that his question was not whether it was possible, but “[w]as it probable to a reasonable degree of medical certainty . . . ” To this, the witness answered:
“Let me put it this way: A lot would depend on whether on, say, autopsy there was another coronary, and if it were in a different place, in a different area, it’s unrelated specifically to that pathology. If nothing specifically was found that was different, but he had coronary insufficiency and died, this, in my mind, is a reasonable probability that it happened the way you said.”
Dr. Bindelglas obviously refused to say that it was probable that the work which he was engaged in at the time of his death was the cause of his death. What he did say was that a lot would depend upon whether an autopsy established that there was another coronary, and if it was in a different area than the right bundle branch block which already existed, and that if nothing was found that was different, in his mind there would be a reasonable probability that it happened “the way you said”, meaning that it was work-related.
Dr. Bindelglas’ testimony falls far short of satisfying the claimant’s burden of proof of establishing to a reasonable probability that Gilbert Fargen’s death was work-related. The most he would say is, as he did say, “it is possible it could have contributed”, meaning that the work was one of the things which could have caused his collapse. Dr. Bindelglas did not even say that it was more likely his work caused Gilbert Far-gen’s death. The reason is obvious. It is simply because, lacking an autopsy, Dr. Bindelglas did not know what had occurred to Fargen’s heart.
Award set aside.
HOLOHAN, V. C. J., and HAYS and GORDON, JJ., concur.