Proceeding pursuant to CPLR 78 (transferred to this court by order of the Supreme Court at Special Term, entered in Albany County) to review a determination of the Comptroller which disapproved petitioner’s application for an accidental retirement allowance pursuant to section 363 of the Retirement and Social Security Law. On February 5, 1972 petitioner suffered a myocardial infarction while in the performance of his duties as a police officer for the New York Port Authority. The denial of accidental disability retirement benefits to petitioner was based on a finding by respondent that the impairment of petitioner’s heart was not the result of an accident but was rather the result of the natural progression of the underlying coronary atherosclerosis from *670which he was suffering prior to and on February 5, 1972. The sole issue before this court is whether the New York State Policemen’s and Firemen’s Retirement System produced sufficient evidence to overcome the statutory presumption that the petitioner’s heart impairment was the natural and proximate result of an accident. Contrary to petitioner’s contention, section 363-a of the Retirement and Social Security Law requires that the heart disability be caused by an accident, and the statute only creates a presumption that the heart impairment was the result of an accident, which may be rebutted by substantial evidence to the contrary (Matter of Weiss v Levitt, 55 AD2d 724; Matter of Bunnell v New York State Policemen’s & Firemen’s Retirement System, 50 AD2d 244, app dsmd 39 NY2d 742). The testimony of the medical expert that the myocardial infarction suffered by petitioner was not associated with any specific physical activity but rather "resulted as an inevitable event related to the natural history of occlusive coronary atherosclerosis”, clearly constitutes substantial evidence to rebut the statutory presumption (Matter of Behan v Levitt, 52 AD2d 963; Matter of Bunnell v New York State Policemen’s & Firemen’s Retirement System, supra). Determination confirmed, and petition dismissed, without costs. Koreman, P. J., Greenblott, Sweeney, Main and Herlihy, JJ., concur.