The plaintiff seeks a review of an order of the Industrial Commission denying him compensation for a disability suffered by him. The plaintiff claims that a pre-exist-ing heart ailment was aggravated while he was performing duties ás a fireman for Salt Lake City.
Evidence of record shows that the plaintiff was of the age of 33 years; that he served in the Army from 1954 to 1958, having received physical examinations yearly and a thorough physical examination upon discharge from the service.
The plaintiff was employed by the Salt Lake City Fire Department from August 16, 1959, and worked continuously from that date until April 7, 1964. Prior to entering employment with the City, the plaintiff was given a physical examination by the City. The plaintiff’s employment was that of a combat fireman, and at the time of the incident here in question, he was on a swing shift which involved filling in at various fire stations for men off duty. He was on duty for a 24-hour period, and then he would be off for a period of 24 hours. On September 24, 1963, the plaintiff had gone to bed at approximately 10:30 p. m. At approximately 1:39 a. m. the following morning, an alarm was received at the fire station. When an alarm is received at the station, the overhead lights come on followed by the ringing of a loud gong.
The plaintiff testified that when the call came in he felt a sense of anxiety; he quickly dressed and ran to the tailboard of the fire truck. It was a part of the operating procedure that the fire engine clear the station within a period of from 10 to 20 seconds. The plaintiff stated that upon reaching the tailgate of the engine, he felt nervous and excited. As the engine pulled out of the fire station, he experienced severe pains just above his diaphragm and extepd-ing upward into his shoulder. At about two blocks from the station he put his arm through a leather strap and held onto the bar at the rear of the truck. At that time he slumped and lost consciousness until the truck reached its destination. At the destination, the plaintiff sat down on the tailboard of the truck and his pain was so severe that it made him want to retch. He was taken back to the fire station in the car of the captain. The captain urged the plaintiff to go home immediately but he elected to stay at the station rather than disturb his wife.
The plaintiff continued to perform his duties as a fireman following the incident of September 25, 1963, until March 16, 1964. *142After the incident of September 25, the plaintiff continued to suffer chest pains although the pains were less severe than on 'the night in question. On March 16, 1964, 'the plaintiff consulted Dr. Clyde F. Null, a local physician and a specialist in internal medicine and cardiovascular diseases. Dr. Null diagnosed plaintiff’s condition as being atherosclerotic heart disease, commonly called hardening of the arteries, plus a congenital abnormality designated Wolff-Parkinson-White syndrome. Plaintiff continued to have increasing pain and distress culminating in his being hospitalized on April 7, 1964, after he had collapsed. The Wolff-Parkinson-White syndrome is unrelated to • the atherosclerotic disease suffered by the plaintiff. This condition affects the rhythm .of the heartbeat and is usually non-disabling. The plaintiff’s condition progressed to such an extent that he is now unable to perform ordinary work; he cannot climb stairs; and he cannot perform ordinary activity without severe pain.
At the hearing before the Commission, Dr. Null was asked whether in his opinion .the events that transpired on September 25, 1963, could have aggravated or precipitated the condition which he later found to exist in respect to the plaintiff’s heart. The doctor was of the opinion that acute stress, strain, emotional aggravation and sudden abrupt exercise, maximum effort, could ''easily have precipitated an occlusion of a coronary artery, or could easily have greatly aggravated any underlying or pre-exist-ing coronary artery difficulty or atherosclerosis. The doctor was further of the opinion that the plaintiff’s having developed pain at that time was very strong evidence that he very likely did indeed aggravate the underlying disease, which must have been present prior to the development of his pain.
. The Commission submitted the matter to a medical panel; the panel submitted its report to the Commission. The plaintiff objected to the report of the panel. The matter was again submitted to the medical panel which later submitted its second report. The second report is in part as follows:
Under date of March 18, 1965, this panel submitted to you its opinion regarding the above named case. This opinion was to the effect that in view of the fact that Mr. Powers was not examined between the episode of September, 1963, and March, 1964, the panel had no certain means of knowing his condition after this alleged accident. By description, however, and subsequent events, it appears that Mr. Powers had that night at least an anginal attack. The panel cannot exclude the possibility that he had a myocardial infarction, but the fact that he did not consult a doctor for six months makes this seem highly improbable to the panel. The panel found it hard to accept the idea that the occupational events of that evening and the attack of that *143evening was sufficient to aggravate preexisting coronary heart disease to ' the point of progressing and disabling heart disease. The panel felt that it was more probable in view of subsequent events that the progression was a natural part of the course of coronary artery disease. The panel felt that the records seemed to show that the events of that evening entailed no more emotional tension than in many other fires that had been the usual part of his occupational duties in the past four years.
The Commission adopted the panel report and denied plaintiffs claim for compensation. The final paragraph of the Commission’s order is as follows:
The heart ailment was not reported for six months after the alleged incident. There was no unusual exertion or unusual emotional stress on the date the alleged accident occurred. In our opinion, the incident of April 7, 1964,1 did not aggravate a pre-existing heart ailment; if any there was, and it surely would not result in damage to a normal heart.
It is therefore ordered that the claim be denied.
It will be noted that the opinion of the medical panel is based in part upon the fact that the plaintiff did not consult a doctor for six months after the incident which occurred in September 1963. ’The panel also made the further finding:
The panel felt that the records seemed to show that the events of that evening entailed no more emotional tension than that in many other fires that had been the usual part of his occupational duties in the past four years.
The fact that there is no direct evidence that plaintiff suffered greater anxiety and emotional tension than usual is not determinative of the fact as to whether an industrial accident had occurred. The evidence is without conflict, that the early morning of September 25, 1963, the plaintiff did in fact suffer an episode of a sudden illness which caused him to lose consciousness in responding to the fire alarm.
It will be noted that the Commission based its finding and conclusion in part upon the fact that the plaintiff’s heart ailment was not reported for six months after the alleged incident. The Commission further found that there was no unusual exertion or unusual emotional distress on the date the alleged accident occurred. The Commission was further of the opinion that a pre-exist-ing ailment was not aggravated.
The law is well settled that the ag-. gravation .or lighting: up ’ of á pre-existing disease by an industrial 'accident is compensable and that ' ah internal.' failure *144brought about by exertion in the course of employment may be an accident within the meaning of the act.2
It would appear that the decision of the Commission was not based upon the evidence before it. It further appears that the Commission applied “unusual strain” test in this case. We are of the opinion that in these cases we are only concerned with the proposition as to whether or not an ordinary exertion as contrasted to an unusual exertion caused the injury in question.
We are of the opinion that the decision of the Commission was not based upon the evidence and is, therefore, arbitrary, and that the order should be, and the same is, reversed. No costs awarded.
CALLISTER and HENRIOD, JJ., concur.