Appeal from a decision of the Workers' Compensation Board, filed December 6, 1977. The board, in reversing the referee, found that the claimant's decedent's death was not causally related to the work effort in which he was employed. The instant case hinges on conflicting medical testimony. The treating physician testified that in his opinion decedent's unusual work effort caused the death by a myocardial infarction. Doctor Cutler testified that from his review of the records, the decedent died from intestinal obstruction, gastrointestinal hemorrhage, acute pancreatitis and liver disease. He further testified that a myocardial infarction was never established. Doctor Fischl, an impartial specialist, testified that in his opinion the patient died as the result of previous abdominal disease unrelated to his work and that there was no evidence of myocardial infarction. Such medical opinions create issues of fact for the board to resolve and, if supported by substantial evidence, the board's determination must be affirmed by this court (Matter of Manbeck v Manbeck Mach. Co., 54 A.D.2d 816). The testimony of Doctor Cutler and Doctor Fischl provided substantial evidence to support the board's determination that the decedent's death was not causally related to the work in which he was engaged and the cause of death was not a myocardial infarction. We therefore affirm the determination of the board. Decision affirmed, without costs. Greenblott, J.P., Main, Larkin, Mikoll and Herlihy, JJ., concur.