On October 21, 1965, Harry Goldklang (the employee) sustained a myocardial infarction. The Division of Workmen’s Compensation (the Division) determined that it was work-connected and compensable and on April 2, 1968 entered a formal award of 25% of partial per*309manent total disability against the employer, Metropolitan Life Insurance Company. In 1970, the employee filed an application for review or modification of the 1968 award. After a hearing, the Division dismissed the application, finding that, since he had had no new accident or infarction since 1965, his “present disability is attributable to the natural progression of his severe coronary artery disease.” On a de novo appeal, the county court reversed and awarded 100% permanent total disability. The latter included severe coronary insufficiency, an enlarged heart and congestive heart failure.1 The employer appeals without in any way disputing the extent of disability if the county court’s determination is correct.
The scope of our review is limited on an appeal from the county court in a workmen’s compensation case, even where the court’s fact determinations are contrary to those of the compensation judge. If the county court’s findings are reasonably supportable on the whole record before it, giving due regard to the conflicting findings of the compensation judge based on his special expertise or superior opportunity to appraise witnesses’ credibility, the county court’s judgment should he affirmed. Close v. Kordulak Bros., 44 N. J. 589, 599 (1965); Kaplowitz v. K & R Appliances, Inc., 108 N. J. Super. 54, 62 (App. Div. 1969). See also MacDonald v. Hudson Bus Transportation Co., 100 N. J. Super. 103 (App. Div. 1968); Stallone v. Schiavone-Bonomo Corp., 103 N. J. Super. 170 (App. Div. 1968), certif. den. 53 N. J. 226 (1969); Pankiewicz v. N. J. Bell Telephone Co., 105 N. J. Super. 287 (1969), aff’d. 53 N. J. 559 (1969).
*310Applying that principle of appellate review, we are satisfied that in this close heart case the county court’s findings and judgment as to compensability are reasonably supportable by the record and should be affirmed, substantially for the reasons given in its opinion.2
Matters of credibility such as witness 'demeanor or other factors of trustworthiness uniquely available to the tribunal before which evidence is adduced in our view were not involved in the compensation judge’s decision. Even if the employee’s testimony as to his allergy or his employment in the business of selling insurance since the 1965 infarction were false, we are not persuaded that that judge’s conclusion in any way was influenced thereby. Similarly, in the light of the other evidence in the record, his continued employment since October 28, 1966 as an insurance salesman does not necessarily impugn Dr. Goodman’s testimony that he had a “straightforward downhill course” after the infarction.
Moreover, the compensation judge’s conelusory determination of lack of causation between the 1965 infarction and the present disabilities, to the extent it represents an exercise of expertise, is not supported by articulated reasons grounded in the evidence.
Dr. Goodman’s statement of the operative factors leading to his opinion on causation might have been stated with greater precision. Nevertheless, it meets the preponderance of evidence standard that the employee here must sustain to. prove the medical causal relationship, to a material and substantial degree, between his 1965 infarction and his present condition. Additionally, Dr. Goodman’s testimony, in contrast to that of Dr. York, accords with the kind of expert proofs as to such causation required in heart cases generally and in matters such as this where increased disability *311is claimed. Dwyer v. Ford Motor Co., 36 N. J. 487, 493-494 (1962); Close v. Kordulak Bros., supra, 44 N. J. at 600-601; Schiffres v. Kittatinny Lodge, Inc., 39 N. J. 139, 148-149 (1963); Aladits v. Simmons Co., 47 N. J. 115, 125 (1966). See Russo v. Teachers Pension and Annuity Fund, 62 N. J. 142, 147 (1973).
A court must act on the basis of the record before it, and oven a tribunal with expertise must predicate its ultimate determination on findings sustained by proofs to which it applies its special knowledge. See Szumski v. Dale Boat Yards, Inc., 48 N. J. 401, 410 (1967); Application of Howard Savings Institution of Newark, 32 N. J. 29, 52 (1960); Talocci v. Strelecki, 93 N. J. Super. 567, 572 (App. Div. 1967)3.
The employer contends that since Dr. Goodman did not examine Goldklang until February 2, 1971, there is a lack of the comparison between his condition in 1968 and his present condition required to prove that the compensable disability increased. It argues that Dr. Silberner, the cardiologist whose reports were used in 1968, Dr. Frank, Goldklang’s principal cardiologist, and Dr. Schneider, apparently Ms present treating physician, should have been produced to testify for this purpose. We find the contention to be without merit. Both Dr. Goodman and Dr. York agreed that Goldklang was 100% industrially disabled at the time of the hearing. A changed condition may properly be shown by the testimony oí a physician who has examined the employee and compared his findings with those of the earlier examining physicians. Yeomans v. Jersey City, 27 N. J. 496, 512 (1958).
*312The county court denied the employee reimbursement for $6,811.95 in expenses involving a series of hospitalizations commencing June 24, 1968. The employee cross-appeals from this portion of the judgment.
Admittedly, prior to filing the present petition for review or modification, the .employee did not notify the employer of his need for treatment or hospitalization, as required by N. J. S. A. 34:15-15. There is no evidence that such notice would have been futile, at least until the employer filed its answer denying liability, or that the hospitalizations are within any statutory exception dispensing with the notice requirement. See Benson v. Coca Cola Co., 120 N. J. Super. 60 (App. Div. 1972); Colbert v. Consolidated Laundry, 31 N. J. Super. 588 (App. Div. 1954).
However, the petition does list the hospitalizations by places and dates and the pretrial memorandum in the Compensation Division provides that medical and hospital bills since the original accident will be submitted. Hence, the employer was aware prior to the hearing that these expenses might be claimed if increased'disability were found. Yet the lack of prior notice of the employee’s need for such hospitalization was not raised by it in the answer, the pretrial memorandum or at the hearing before the compensation judge. Accordingly, that defense was waived. See Conway v. Mister Softee, Inc., 51 N. J. 254 (1968); Hinz v. Western Electric Co. Inc., 9 N. J. Super. 93 (App. Div. 1960). The part of the county court judgment denying reimbursement of hospital expenses must be reversed.
The focus of the hearing in the Division was on the issue of compensability. Dr. Goodman, over objection, testified as to the reasonableness of the hospital expenses. Although no contrary evidence was offered, the proofs as to the necessity for or reasonableness of these substantial expenses was sparse. Additionally, there was no evidence that the employee, rather than a third party, was entitled to payment from the employer of any particular hospital bill. See N. J. S. A. 34:15-15, 34:15-15.1; Stafford v. Pabco Products, *313Inc., 53 N. J. Super. 300 (App. Div. 1958); Bielak v. Counties Contracting & Const. Co., 95 N. J. Super. 266 (Law Div. 1967); Hunt v. Hospital Service Plan of N. J., 33 N. J. 98 (1960).
These circumstances require that a plenary hearing be held before the Division as to the hospital expenses so that an appropriate determination may be made with respect thereto.
The judgment of the county court is aiRrmed in part and reversed in part. The case is remanded to the Division of Workmen’s Compensation for further proceedings consistent with this opinion. We do not retain jurisdiction.
Dr. Goodman, the employee’s medical expert, gave as his diagnosis: “arteriosclerotic heart disease with the residuals of acute myocardial infarction, aortic stenosis, severe coronary and myocardial insufficiency, cardiac panarrahythmia with the residuals of a post myocardial infarction pulmonary embolism.” Dr. York, the employer’s expert, diagnosed the present condition as “arterioscierotic cardiovascular disease, with an enlarged heart, and he also had chronic bronchitis with pulmonary emphysema.”
We note an apparent error in the opinion as to the first hospitalization in Christ Hospital. The period should be from June 24 to June 28, 1968, rather than June 24 to July 28, 1968.
The causal relation between a compensable infarction and subsequent increased coronary or heart disability is not precluded automatically merely because a substantial period of time has elapsed since the infarction, even though the employee has an underlying heart condition or sclerotic disease of the coronary arteries which is progressive in nature. The matter is still one of proof of medical causation. Schiffres, supra, 39 N. J. at 150; Close, supra, 44 N. J. at 601.