Section 607-D. Disability benefits

A  county  may  elect  to make the
  benefits provided herein available to the sheriff, undersheriff,  deputy
  sheriffs   who   are   engaged  directly  in  criminal  law  enforcement
  activities, and correction officers who are in the employ of the county.
  Notwithstanding any provision of this chapter or any general or  special
  law  to  the  contrary,  any condition of impairment of health caused by
  diseases of the heart, resulting in the disability or death to a  member
  covered by this section, presently employed and who shall have sustained
  such  disability  while  so employed, who successfully passed a physical
  examination on entry into service as a member covered by  this  section,
  which  examination  failed  to disclose evidence of any disease or other
  impairment of the heart, shall  be  presumptive  evidence  that  it  was
  incurred  in  the performance and discharge of duty, unless the contrary
  can be proved by competent evidence.
    * NB Expires June 30, 2011