Claimant, a plumber, then sixty-four years of age, was engaged in installing plumbing in a housing development, and had been so employed by the employer for about seven months. In the afternoon of July 8, 1948, he was sent to the top or sixth floor of one of the buildings to do some work. It was a hot day, and claimant had to walk up the six stories because the elevator was not operating at the time, carrying his tools, some fixtures and a tank of gas for soldering, a total weight of about fifty-five pounds. On arriving at the sixth floor he was exhausted and puffing, but proceeded with his work, which required the use of a burning torch. After working about an hour and a half claimant collapsed and was unable to catch his breath. Claimant was hospitalized for five and one-half weeks and his condition diagnosed as "an acute left ventricular failure due to an excessive strain and stress on the cardiac musculature." A later diagnosis of pre-existing "coronary artery sclerosis hypertension, bundle branch block and a paroxysmal nodal tachycardia" was made. The board has found that claimant's activities on July 8, 1948, above outlined, subjected him to unusual strain and exertion, and resulted in accidental injuries to his heart and the resulting disablement. While the medical testimony presented sharply conflicting views, there is here presented only a question of fact which is exclusively within the province of the board to decide. The facts in this case are similar to Matter of Klein v. Louis Candel, Inc. ( 280 App. Div. 1029). Decision and award unanimously affirmed, with costs to the Workmen's Compensation Board.