etiology, valve obstruction or regurgitation causes characteristic physical and laboratory findings.  Secondary infective endocarditis  is a continuing hazard for these patients.  Antistreptococcal  prophylaxis is advisable. (Reference: Mercks Manual, 14 t h  Edition, page 526). [ 1 1 ]  (Emphasis supplied)   The respondent failed to prove that his work conditions had predisposing factors that caused Rheumatic Fever which, in turn, led to Rheumatic Heart Disease, the subject ailment. Exposure to toxic chemicals and biological hazards does not by itself constitute the cause of respondents ailment. Moreover, respondent failed to present evidence that he ever contracted Rheumatic Fever which could have led to Rheumatic Heart Disease.   The ECC correctly held:   It is well-settled under the Employees Compensation Law that when the claimed contingency is not the direct result of the covered employees employment, as in the instant case, and the claimant failed to show proof that the risk of contracting the disease was increased by the covered employees employment and working conditions, the claim for compensation benefits cannot prosper. Since there is no causal relation between [respondents] ailment, Valvular Heart Disease, and his employment and working conditions; nor are there indications that the nature of his work had increased the risk of contracting the said disease, [the petitioner] is correct in denying [respondents] application for compensation benefits under PD No. 626, as amended. [ 1 2 ]   The Court affirms the findings of the agencies a quo. The CA erred in disregarding the findings of the ECC on the technical matter concerning the nature of respondents illness.   This is one instance when, pursuant to prudence and judicial restraint, a tribunals zeal in bestowing compassion must yield to the precept in administrative law that in [the] absence of grave abuse of discretion, courts are loathe to interfere with and should respect the