Decision #96/03 - Type: Workers Compensation

Preamble

An Appeal Panel hearing was held on July 16, 2003, at the employer's request. The Panel discussed this appeal on July 16, 2003.

Issue

Whether or not the claim is acceptable.

Decision

That the claim is acceptable.

Decision: Unanimous

Background

During the course of his employment as a subcontractor installing ventilation in the mines on February 4, 1997, the claimant noticed that his throat was swelling up and he was having a hard time breathing. The claimant indicated that he started to sweat and became unsteady on his feet. He was then given a ride by a co-worker who drove him to the shaft. As the claimant thought he only had a sore throat he did not go to the hospital until the next morning. Medical reports on file diagnosed the claimant's condition as a myocardial infarction.

The employer's report indicated that the claimant came to the surface at 8:15 p.m. and said he wasn't feeling well. He then called on February 5, 1997 to state that he had "swollen enzymes."

In order to adjudicate the claim, a WCB adjudicator contacted the claimant to ascertain the exact nature of the work duties that he had been performing on February 4, 1997. All file information including the medical reports on file were then reviewed by a WCB consultant in internal medicine at the request of primary adjudication. The consultant's comments are outlined in a memo dated May 7, 1997.

In a decision dated May 14, 1997, primary adjudication informed the claimant that his claim was not acceptable as the claim did not meet the criteria of the board's policy dealing with myocardial infarctions:

The adjudicator commented that the claimant's symptoms occurred while he was performing work which was not out of the ordinary. The claimant also suffered from an underlying cardiovascular disease which could not be related to his employment.

In correspondence to the Review Office dated December 28, 2001, legal counsel for the claimant appealed the above decision. Legal counsel contended that the conditions in which the claimant was working were out of the ordinary. "There was inadequate ventilation and diesel fumes were present in the air. Mr. [the claimant's] physician [physician's name] indicates that the lack of clear ventilation was a precipitating factor in his MI." A report from a cardiologist dated October 6, 1998 was also submitted for information.

Prior to considering the appeal, Review Office attempted to obtain environmental data from the company which owns the mine and from the employer for whom the claimant was working. However, Review Office was informed that this type of information was not routinely kept in the records.

Review Office also wrote to the WCB's consultant in internal medicine, asking him to review the new medical information and to comment on how a lack of ventilation would be a precipitating factor and whether or not there was a specific degree of ventilation or lack thereof that would be a threshold for causing or precipitating a MI. The consultant's response is contained in a memo dated September 10, 2002.

In a decision dated September 13, 2002, Review Office determined that the claim for a myocardial infarction was acceptable. Review Office noted the opinion expressed by the WCB's consultant that the poor ventilation which resulted in poor levels of oxygen caused the worker to become hypoxic resulting in an infarction. "This would occur if the person has proven diffuse coronary artery disease and this has been established with this worker. In the opinion of Review Office, this satisfies the policy requirements for a trigger factor in the work environment which has caused the cardiac event to occur. The claim is therefore acceptable.

On November 1, 2002, the employer's Safety Director appealed Review Office's decision. He stated, "There was no event or trigger factor, just speculation from doctors and cardiologist who have never been underground. Other workers were working in same area. The accepted trigger factor is weak at best. Nobody from Review Office contacted [name] to request environmental data." On July 16, 2003, an oral hearing was held at the Appeal Commission.

Reasons

This case involves a worker who suffered a myocardial infarction while working as an underground miner in February 1997. His claim for compensation was not accepted initially. Upon reconsideration by Review Office, this decision was reversed and his claim accepted. The employer appealed that decision to the Appeal Commission.

For the appeal to succeed, the Appeal Panel would have to determine that the myocardial infarction was not caused by a triggering event as required by board policy. We did not come to that determination.

In coming to our decision, we conducted a thorough review of the claim file, as well as holding a hearing, at which we heard testimony from the appellant employer, the claimant and his legal counsel.

Board Policy 44.10.10.60, Myocardial Infarctions sets out the conditions under which a claim for such a heart attack will be accepted as a compensable injury. It reads, in part:

"The WCB will adjudicate claims involving myocardial infarctions by first determining the compensability of any underlying cardiovascular disease that is present. … If it is determined that the underlying cardiovascular disease is not compensable, then the myocardial infarction will be adjudicated as an accident.

  1. A myocardial infarction will be compensable if the following criteria are met:

    1. An event or trigger factor has occurred that is deemed to be significant and which occurred in the course of employment and arose out of the employment. In order for a work cause to be determined to be the cause of a myocardial infarction, medical evidence of causation must be available and the factors believed to have caused it must create conditions in significant excess of the conditions that the worker experiences on a regular basis …"
At the hearing, the claimant testified that he had not had a heart attack prior to the February 1997 attack. However, he did have diffuse coronary artery disease, a pre-existing condition that may have predisposed him to having a heart attack.

It is accepted that, pursuant to board policy, his coronary artery disease was not compensable. Therefore, for his claim to be accepted, a triggering factor would have had to have occurred. The initial adjudicator found that such a triggering event had not occurred, noting that the claimant admitted that the work he had been doing was not out of the ordinary for him, that he had done similar work in similar conditions on many occasions. The adjudicator also placed considerable weight on the underlying cardiovascular disease as a contributing factor.

Review Office, in its decision, found such a triggering event. We agree with that finding.

In particular, Review Office found that the worker was working in conditions with poor ventilation and diesel fumes. Medical opinion held that the poor ventilation would lead to poor levels of oxygen causing the claimant to become hypoxic resulting in an infarction. Review Office noted further that this would occur in a person with proven diffuse coronary artery disease.

From the evidence on file and from the testimony given at the hearing, we know that the claimant was working in the following conditions at the time of his attack:
  • He was working underground at the 3400-3500 level, in a drift (tunnel) that was about 15 feet wide, 12 feet high and, at least 100 feet long.
  • He was on the top deck of a scissor lift machine, installing 48 inch ventilation tubing.
  • At different points along this tubing, there are 48 inch fans. These fans are turned off while installing the tubing.
  • The normal temperature in the drift would be about 70 - 75 degrees Fahrenheit. However, he was working about 10 - 12 feet above the floor, so, it would be hotter.
  • The scissor lift, powered by a diesel engine, was running continually while he worked on the ventilation tubing.
  • There was a scooptram, also diesel-powered, working in an outside corridor, albeit near the open end of the drift in which he worked.
The employer's representative countered that neither the employer, nor the mine's owner would allow the air quality to deteriorate below legally-required standards. We do not doubt this to be the rule. However, we do find that there could well be particular circumstances in which air quality does deteriorate in isolated areas, for particular times. We have concluded that - on a balance of probabilities - that is what occurred in the drift in which the claimant was working.

In reviewing the medical evidence on file, we note the following:
  • The diagnosis, in February 1997, was myocardial infarction.

  • On April 11, 1997, a board medical advisor expressed the opinion that the poor air quality, combined with the claimant's arterosclerotic heart disease, could possibly be a triggering event. But, he deferred to a specialist as to whether the heart attack was caused by his work activities.

  • In a memo dated May 7, 1997, an internal medicine consultant to the board noted that the initial arteriography had suggested a clot in the first right ventricular marginal branch. This would suggest an acute event, but he could find insufficient evidence to confirm this as the trigger event. He stated he was unable to identify a cause for the attack. He noted the claimant's existing coronary artery disease, as well as other possible contributing factors, including that the claimant was overweight and a smoker.

  • In a letter dated October 6, 1998, a cardiologist treating the claimant expressed the opinion that the lack of clear ventilation in the workplace was a precipitating factor in his myocardial infarction.

  • In September 2002, the board's internal medicine consultant wrote:

    "The running of diesel motors and poor ventilation would result in low levels of oxygen in the environment, causing a person to become hypoxic, which could result in an infarction in a person with diffuse coronary artery disease. The problem could be further compounded by the exhaust fumes from the diesel, which might have contained carbon monoxide and oxides of nitrogen and sulphur, causing further hypoxia and irritation to the lungs."
We have already concluded that there was poor air quality in the claimant's work area at the time of his heart attack. The foregoing medical evidence indicates that poor air quality can very well lead to a myocardial infarction in a person with the claimant's pre-existing arterial disease. This leads us to conclude - on a balance of probabilities - that the poor air quality provided the trigger event which led to the claimant's heart attack.

Thus, we uphold the decision of the Review Office: the claim is acceptable. Accordingly, the appeal is dismissed.

Panel Members

T. Sargeant, Presiding Officer
A. Finkel, Commissioner
M. Day, Commissioner

Recording Secretary, B. Miller

T. Sargeant - Presiding Officer
(on behalf of the panel)

Signed at Winnipeg this 3rd day of September, 2003

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