dissenting.
I agree with the Majority that the decedent was actually engaged in activities in furtherance of Employer’s business or affairs at the time of his injury and thus was acting in the course of his employment. I must respectfully dissent, however, from the Majority’s conclusion that the Board must be reversed because “[Dr. Hurwitz’] testimony is the necessary substantial evidence to support a finding that the death was work-related.” At 1171. In reaching this conclusion, the Majority has usurped the fact-finding function of the referee in disregard of the applicable scope of review by this Court.
The Majority rejects the referee’s clear findings of a lack of causal connection between the decedent’s employment and his heart-related injury1 by simply stating that “a reading of the entire decision of the referee shows that his decision was based upon the conclusion that the decedent was not in the course of his employment____” Id. The Majority then concludes that Dr. Hurwitz’ testimony that the decedent’s strenuous exercise was the immediate and precipitating cause of his death supports a causal connection.2
A claimant who seeks benefits for a heart-related injury has the burden of establishing by unequivocal medical testimony a causal connection between the employment and the heart-related injury. Brody v. Workmen’s Compensation Appeal Board (Pennsylvania Public Utility Commission), *104138 Pa.Commonwealth Ct. 456, 588 A.2d 575 (1991). In a worker’s compensation case in which the Board takes no additional evidence, the referee is the ultimate fact finder and his or her findings of fact, if supported by substantial evidence, must be accepted as true. Yantos v. Workmen’s Compensation Appeal Board (Vulcan Mold & Iron Co.), 128 Pa.Commonwealth Ct. 231, 563 A.2d 232 (1989). Further, the referee, in evaluating evidence, may accept or reject testimony of any witness, including a medical witness, in whole or in part. Kraemer v. Workmen’s Compensation Appeal Board (Perkiomen Valley School Dist.), 82 Pa.Commonwealth Ct. 469, 474 A.2d 1236 (1984). Moreover, when reviewing the referee’s findings of fact, this Court is not to weigh evidence but merely to determine whether the whole record contains evidence which a reasonable person might find sufficient to support the referee’s findings. Lewis v. Commonwealth, 508 Pa. 360, 498 A.2d 800 (1985). A review of the record clearly demonstrates that irrespective of the referee’s erroneous conclusion that the decedent was not in the course of his employment, the referee’s findings of a lack of causal connection are supported by substantial evidence and the order of the Board, therefore, must be affirmed.
The referee found that the decedent used the same exercise program which he used on the morning of his death for nine months. Referee Findings of Fact No. 7. Dr. Hurwitz testified that considering the decedent’s family history and medical conditions including severe coronary artery disease, high levels of cholesterol, and two previous myocardial infarctions, one of which occurred several days prior to his death, an episode of sudden death could have occurred at any time. Dr. Hurwitz stated on cross-examination:
Q. Doctor, how would you classify the severity of Mr. Stanner’s coronary artery disease by the pathologist?
A. Severe.
Q. With that degree of severity, Doctor, is it possible to predict when anybody will have a heart attack?
*105A. It’s not possible to predict when they’ll have a heart attack. It is possible to predict what kinds of events may make him at higher risks for sudden cardiac events, but one can’t make a definitive prediction.
Q. Doctor, looking at just the description of the coronary arteries, it is possible, in consideration of Mr. Stanner’s total picture, that this sudden-death episode could have occurred while he was asleep or walking or sitting?
A. Yes. He was a candidate for sudden death. There’s no question.
Q. Regardless?
A. Regardless of where or when he was. However, there are settings in which sudden death is more likely to occur with this anatomy, and those settings are really those in which there is physical activity involved, because physical activity can precipitate these sudden rhythm disturbances.
Q. Would you have considered him a walking time-bomb, and we’re talking in hindsight with the autopsy results and his history?
A. Yes. Given the anatomy, any physical activity or any sudden increase in stress would have precipitated what eventually happened to him.
Deposition of Larry E. Hurwitz, M.D., pp. 23-24, 26.
The Majority correctly notes that Dr. Hurwitz’ concession or contradicting testimony that sudden death syndrome could have occurred at any time goes to the weight of his opinion. At 1171. It was therefore within the referee’s exclusive province and not this Court’s to weigh that evidence and to make a credibility determination considering Dr. Hurwitz’s testimony in its entirety. Brody. Since the record supports the referee’s findings of a lack of causal connection between the decedent’s employment and his injury, this Court may not disturb his findings.
Accordingly, I would affirm the order of the Board.
. Referee Findings of Fact Nos. 8, 10.
. The Majority’s assertion that the referee found credible Dr. Hurwitz’ testimony that the decedent’s strenuous exercise was the immediate and precipitating cause of death is not supported by the record. The referee in his Findings of Fact No. 6 simply sets forth a summary of Dr. Hurwitz’ testimony without making a credibility determination.