In this appeal we are presented with the issue of the applicability of the North Dakota aggravation statute, § 65-05-15, NDCC, in this workmen’s compensation action, which would require payment of only that proportion of death benefits arising from the aggravation of a preexisting coronary disease which resulted in the heart attack and death of Archie A. Stout in the course of his employment. We affirm the decision of the district court of Grand Forks County denying apportionment and awarding the claimant, Alice G. Stout, full benefits under the Act.
For purposes of this appeal, we restate the factual situation as set forth in our previous review of this case in Stout v. N.D. Workmen’s Compensation Bureau, 236 N.W.2d 889, 890-91 (N.D.1975):
“Alice G. Stout applied for workmen’s compensation death benefits for the death of her husband, Archie A. Stout, who died on November 26, 1973. The Workmen’s Compensation Bureau denied the claim, she appealed, and the district court reversed the Bureau and entered judgment for her. The Bureau appeals. We affirm.
“Stout was a truck driver. On the date of his death he delivered freight to a grain elevator at Thompson, North Dakota. The freight consisted of an anhydrous ammonia stand which carried two *430immovable metal reels intended to hold hoses. Stout and the manager of the elevator slid or skidded the machine off the truck onto a pickup truck. The machine weighed about 150 pounds and the effort involved was not strenuous. Almost immediately, Stout complained of not feeling well and of pain in his arm and chest. He went to the office and sat down. He called his employer in Grand Forks and asked to be picked up and returned home since he was unable to drive the truck. A few minutes later, he was dead. The cause of death was myocardial arrest.
“There was no inkling of heart disease in Stout’s prior medical history. In February of 1973, an electrocardiogram was taken and it was normal. In October of 1973, prior to a prostate operation, he had a physical examination and the report shows that his heart tones were regular and of good quality and there was no enlargement or heart murmur. He returned to work on November 12, and his work was uneventful until the day of his death.
“An autopsy was performed. It showed atherosclerotic occlusion of the proximal portion of the right coronary artery and severe pulmonary edema.
“Mr. Stout’s physician, who had examined him twice previous to the date of his death, testified that it was his opinion '. . . that Mr. Stout’s exertion did precipitate the coronary insufficiency that resulted in acute cardiac failure and pulmonary edema and subsequent death.’ He was asked, ‘And is it your opinion that the exertion, moving this object, although it may not have been any great exertion, could precipitate the coronary insufficiency?’ and he replied, ‘It is indeed.’ As to causation, he said that the facts speak for themselves: ‘. . .he was at work, he did exert within a period of a minute or two and he developed a severe illness and died shortly thereafter.’ He said that the pulmonary edema could occur within a very short time, and there was no evidence of any prior heart attack.
“The Bureau offered no evidence to contradict that of the plaintiff’s physician.
“The Bureau, however, apparently relied on further testimony of the doctor that Stout had preexisting ‘bad coronary disease’ and that ‘He was, you might say, walking a thin line every day maybe for years.’ The Bureau apparently concluded that the death was caused by the preexisting heart condition, and not by the exertion, although the Bureau concedes that the evidence shows that the exertion of moving the anhydrous ammonia stand precipitated the death.”
The last sentence quoted above, we believe, correctly reflects the Bureau’s position at previous stages of this litigation, that the cause of Mr. Stout’s death was not work-related and thus death benefits should be denied entirely. In holding that the claimant, Alice G. Stout, was entitled to death benefits, we did not decide the applicability of § 65-05-15, NDCC, the aggravation statute, to this case, since that issue was not presented for our review, although the concurring opinion indicated that that statute should be recognized.
On remand, the Workmen’s Compensation Bureau apparently adopted the position in this case that if the claimant is entitled to benefits they should be paid on an arbitrary fifty percent pro rata basis. In so doing, the Bureau apparently applied § 65-05-15, NDCC, as mentioned in the concurring opinion of Justice Sand, without, however, satisfying those basic requirements pointed out in that concurring opinion.
No hearing has been held at which any testimony has been introduced into the record which would permit the application of the provisions of the statute which authorize the proration of benefits when a claim is made under the provisions of the Workmen’s Compensation Act.
In holding that Mrs. Stout is entitled to full death benefits in this action, we do not wish to indicate that the aggravation statute would not be applicable in another appropriate case under similar circumstances if the Workmen’s Compensation Bureau *431had introduced the necessary evidence to support a proration of the benefits.
Section 65-05-15, NDCC, is a legislative directive which permits the Bureau to apportion benefits in a proper case. Section 65-05-15 provides:
“In case of aggravation of an injury or disease existing prior to a compensable injury, compensation, medical, hospital or funeral expenses, or death benefits, shall be allowed by the bureau and paid from the fund only for such proportion of the disability, death benefits, or expense arising from the aggravation of such prior disease or injury as reasonably may be attributable to such compensable injury. But any compensation paid on the basis of aggravation shall not be less than ten dollars per week unless the actual wages of claimant shall be less than ten dollars, in which event the actual wages shall be paid in compensation.”
In construing a similar statute in Tingle v. Board of County Com’rs (Dade Co. Port Auth.), 214 So.2d 1, 2 (Fla.1968), the Florida Supreme Court stated:
“We are obviously faced with the necessity (however difficult or impractical it may be) of giving some effect to the statutory provision that in case of accidental acceleration of pre-existing disease ‘only acceleration of death * * * at-tributablé to the accident shall be com-pensable. * * *’ To hold that every death resulting from accidental acceleration of pre-existing disease is fully com-pensable is to ignore this language, and results in confining apportionment under this section to death caused independently by the pre-existing disease. Manifestly that is not the intent of this section since (1) such a death could never in the first instance be brought within the act, (2) it would not require the application of an apportionment section, and (3) with reference to the particular terms of Sec. 440.02(19), a death caused independently by disease would not even involve the acceleration of disease by accident. The literal language of this section is a limitation on the ordinary rule under the act by which death causally related to an accident is compensable, and provides, in the case of pre-existing disease, for compensation only for acceleration rather than full death benefits.
“The statute makes no distinction between active and quiescent pre-existing disease, and in view of the undisputed evidence in this case that claimant’s preexisting disease was accelerated by a compensable heart attack which would not otherwise have caused his death, we think it is clear that the law requires that compensation be limited to the extent of acceleration.”
On remand in the Florida case, medical testimony was received in a subsequent hearing and it was determined that benefits could be apportioned on a percentage basis, and that award was affirmed in Tingle v. Dade County Board of County Com’rs, 245 So.2d 76 (Fla.1971). At oral argument in the instant case, the Bureau argued that medical testimony was difficult to obtain in these cases for apportionment purposes, and thus the Bureau had adopted the practice of awarding benefits on a fifty percent basis in all such cases. We do not approve of this practice of arbitrarily selecting an apportionment figure of fifty percent in heart attack cases. As Justice Sand said in his concurrence in the first Stout decision:
“The extent of the aggravation is basically a medical fact question to be resolved by the agency under appropriate rules of law. Even though it may be difficult in some instances to determine with exact precision the extent of the aggravation and the resulting proportionate benefits, nevertheless the statute contemplates that a reasonable effort be made.” 236 N.W.2d at 895.
The California court, in City of Glendale v. Industrial Accident Commission, 153 Cal.App.2d 213, 314 P.2d 182, 184 (1957), stated much the same thing:
“The difficulty of making an apportionment does not relieve the commission of the duty imposed on it by statute.”
If the Bureau wishes to invoke the aggravation statute in a proper case (but not this *432one), it should do so after receiving sufficient medical testimony during a properly conducted evidentiary hearing. We adopted the so-called “usual exertion" rule in the first Stout decision and we deem it pertinent that we acknowledge that the Forty-fifth Legislative Assembly, in Senate Bill 2158, amended § 65-01-02(8), NDCC (effective July 1,1977), by inserting in the definition of “injury” the following language: “If an injury is due to heart attack or stroke, such heart attack or stroke must be causally related to the worker’s employment, with reasonable* medical certainty, and must have been precipitated by unusual stress.”
The judgment is affirmed.
ERICKSTAD, C. J., and PAULSON and SAND, JJ., concur.