We are asked to determine whether the award of workers’ compensation benefits in this case was proper in view of our decision in
Kostamo v Marquette Iron Mining Co,
I
Plaintiff John A. Miklik 1 was hired by defendant Michigan Special Machine Company in 1953 at age 25. Miklik, a journeyman toolmaker and machinist, first worked for the company as a fixture builder; in 1959 or 1960 he became a "leadoff” man, supervising the construction of machinery.
Miklik also worked as a serviceman for Michigan Special Machine, a job which required him to supervise the installing and servicing of machinery in other plants. This work primarily was confined to the Midwest, although Miklik did travel to Italy and was on assignment in France for several weeks in 1965.
At various times in his life, Miklik apparently was beset with health problems, including scarlet fever, rheumatic heart disease, diabetes, obesity, hypertension, and liver damage. He was absent from his job for severаl periods from January, 1973, until he left permanently in October, 1974.
*367 Miklik successfully applied for workers’ compensation benefits in 1975. He contended that stress, strain, anxiety, and other incidents of his employment had caused hypertension, and had aggravated and accelerated pre-existing arteriosclerosis and rheumatic heаrt disease. The hearing referee found Miklik to be permanently and totally disabled. The WCAB affirmed, 2 and the Court of Appeals denied leave to appeal.
This Court remanded the case to the WCAB for reconsideration in light of
Kostamo.
II
In all successful workers’ compеnsation cases, the claimant must establish by a preponderance of the evidence both a personal injury and a relationship between the injury and the wоrkplace. In heart cases, the first question is whether there is heart, damage. The second is whether the heart damage can be linked by sufficient proof to the еmployment. Only if the first question is answered affirmatively need the second be asked.
The existence of heart damage is, of course, a matter of medical proof. The factfinder in a workers’ compensation case ordinarily is free to accept the most persuasive medical testimony. However, should the mediсal testimony advance a theory *368 which conflicts with the law, the factfinder would be precluded from adopting that testimony.
In assessing heart cases, the factfinder is сontrolled by the syllogistic analysis of the Kostamo majority: The Legislature has determined that ordinary diseases of life are not compensable. Arteriosclerosis is an ordinаry disease of life. Therefore, arteriosclerosis is not compensable. 4
Thus, it would be an abuse of a factfinder’s legal discretion to accept medical testimony that a worker with arteriosclerosis and nothing more is a worker with compensable heart damage. Arteriosclerosis is by legal definition an ordinary diseаse of life; it follows, therefore, that arteriosclerosis is not compensable heart damage.
However, even though arteriosclerosis alone does not justify compensation, neither does it bаr compensation. Heart damage, such as would result from a heart attack, is compensable if linked by sufficient evidence to the workplace. The avаilability or unavailability of compensation does not hinge on whether the claimant previously was in excellent health or had a health problem. With respeсt to eligibility for compensation, the employee with arteriosclerosis, even though more *369 susceptible to a heart attack, stands on equal footing with the employee who had no earlier cardiovascular difficulties.
The WCAB, upon remand, accepted medical testimony that Miklik’s health problems were job-related, and then found them to be compensable. The board failed to follow Kostamo’s direction that in order for there to be compensation there first must be an injury. It is impossiblе to turn arteriosclerosis into compensable heart damage merely by labeling it so. The board’s opinion, worded in conclusory terms, ignored this premise of Kostamo. Testimony, at most, showed the progressive effects of arteriosclerosis, not separate heart damage.
In fact, the WCAB, on remand, noted that in its first opinion it had relied on the testimony of Miklik’s medical expert, who said that "work aggravation of the hypertensive arteriosclerotic heart disease caused plaintiff’s disability”. The board later found that Miklik was the victim of hеart damage, concluding that "the stressful employment aggravated the pre-existing arteriosclerotic heart condition”. Such a bald assertion completely ignores Kostamo.
The main issue in two of the five cases which comprised Kostamo was whether there had been heart damage. The Court stated that the occurrence or non-occurrence of a heart attack is a purely medical dispute; faced with conflicting expert testimony, the WCAB was compelled to decide the issue. The board concluded that in neither case had a hеart attack occurred; thus, there was no heart damage. This Court affirmed and emphasized that absent such "proof’ of heart damage, the *370 presence of arteriosclerosis alone would not support an award of benefits.
"Although there is a causal relationship between the underlying disability, arteriosclerosis, and [сlaimants’] inability to continue working, that disability was not caused and could not have been aggravated by their employment.” Kostamo, p 118.
Ill
Even if the WCAB had had adequate support for its finding оf heart damage in Miklik, the board further failed to show a sufficient link between the damage and the workplace. There must be a relationship proved between thе damage and speciñc incidents or events at work. General conclusions of stress, anxiety, and exertion over a period of time do not satisfy this second requirement. Therе must be enough detail about that which precipitated the heart damage to enable the factfinder to establish the legal connection by a prepоnderance of the evidence.
The link between the work and the heart damage need only be one of reasonable relationship of cause and еffect. Other possible or probable causes need not be excluded beyond doubt. Further, the work need not be the sole cause of the damage; it is sufficient if the employment is a cause. The factfinder must identify and evaluatе the discrete factors of employment which are connected to the damage. The Kostamo Court noted several examples which have been regarded аs significant by courts and commentators: temporal proximity of the cardiac episodes to the work experience, hot and dusty conditions, repeated return to work after a cardiac episode, and mental stress.
*371 The WCAB’s conclusion in Miklik that general stress existed without a link between a specific incident of employment and a specific cardiac episode does not suffice. Accordingly, we reverse the decision of the WCAB.
The present Court, while unanimously concurring in this opinion, is equally divided on the question of whether, in light of the reversal of the WCAB, this case should be remanded for further proceеdings. Not wishing to affirm the WCAB by such division, a majority of the Court directs that this case be remanded to the WCAB for further proceedings not inconsistent with this opinion.
Notes
Plaintiff John A. Miklik died on November 26, 1979. His widow, Doris Miklik, personal representative of his estate, subsequently was added as a plaintiff in this case.
Miklik v Michigan Special Machine Co, 1979 WCABO 113.
Miklik v Michigan Special Machine Co (After Remand), 1980 WCABO 857.
At the time of Miklik’s alleged injury, the pertinent language of the statute was: "Ordinary diseases of life to which the public is generally exposed outside of the employment shall not be compensable.” MCL 418.401(c); MSA 17.237(401)(c).
Effective January 1, 1982, that portion of the statute now reads:
"An ordinary disease of life to which the public is generally exposed outside of the employment is not compensable. Mental disabilities and conditions of the aging process, including but not limited to heart and cardiovascular conditions, shall be compensable if contributed to or aggravated or accelerated by the employment in a signiñcant manner”.
We emphasize that our decision in this case rests solely on the statutory language at the time of the alleged injury.