Appeal by the employer and its carrier from a decision of the board discharging the Special Disability Fund on the ground that the employer did not have knowledge of a permanent pre-existing physical impairment within the meaning of subdivision 8 of section 15 Work. Comp. of the Workmen's Compensation Law. The second injury upon which appellants' claim for reimbursement is predicated, occurred on April 2, 1955 when claimant, employed as a fitter and tailor, felt pain in his chest and experienced dizziness while picking up an iron and pressing board. The claim relating to this incident was heard concurrently with a claim for an alleged accident occurring on July 13, 1954. The 1955 claim was established by medical testimony to the effect that claimant sustained a coronary thrombosis and that the lifting was a competent producing cause thereof. The 1954 claim was disallowed. Although the employer's report of injury in 1954 described the claimant's injury as a "claimed heart attack", the proof showed that nothing had happened to claimant in the way of an "accident." However there is evidence that claimant, in 1954 and earlier, was suffering from cardiac insufficiency which together with the subsequent thrombosis, made his condition substantially worse than it was before. Appellants contend that the employer had knowledge of this pre-existing impairment. The employer did not testify on the question of knowledge and the only relevant testimony on this point was given by Dr. Kimmel, claimant's personal physician. Dr. Kimmel testified that claimant had been his patient since 1952. On March 9, 1953, an electrocardiogram showed myocardial damage, and in July or August, 1954, Dr. Kimmel again diagnosed myocardial damage. On August 16, 1954, Dr. Kimmel purportedly wrote a letter to claimant's employer notifying that company of claimant's condition. This letter, addressed "TO WHOM IT MAY CONCERN", described Dr. Kimmel's findings upon a physical examination of claimant. His diagnosis was "cardiac insufficiency". The letter further stated that claimant had been advised to rest for a period of four weeks. There is no indication in claimant's testimony that he personally informed his employer of his condition; nor is claimant's physical impairment of a kind which is patently obvious. (See, e.g., Matter of Sheldon v. Doughty's Laundry Serv., 4 A.D.2d 909.) While the contents of the letter might present a reasonable basis upon which the employer might or might not form a conclusion or belief that the injury was permanent ( Matter of Vance v. Ormsby, 6 A.D.2d 960; Matter of Dugan v. Muller Dairies, 282 App. Div. 590) there is no proof in the record that the employer concluded that it was. The board decided the question of fact presented in favor of the respondents. On the state of the record presented we are not disposed to disturb its determination. Decision unanimously affirmed, with costs to the Workmen's Compensation Board.