A heart attack is a compensable injury under this subtitle only if:

(1) the attack can be identified as:

(A) occurring at a definite time and place; and

(B) caused by a specific event occurring in the course and scope of the employee’s employment;

(2) the preponderance of the medical evidence regarding the attack indicates that the employee’s work rather than the natural progression of a preexisting heart condition or disease was a substantial contributing factor of the attack; and

(3) the attack was not triggered solely by emotional or mental stress factors, unless it was precipitated by a sudden stimulus.

Acts 1993, 73rd Leg., ch. 269, § 1, eff. Sept. 1, 1993.