State News : South Dakota

In Arneson v. GR Mgmt., LLC, 2024 S.D. 61, 13 N.W.3d 206, the claimant, Mr. Michael Arneson (“Arneson”), worked as a maintenance manager at a hotel and casino in Deadwood, South Dakota. On July 18, 2018, Arneson was working on a commercial exhaust fan for his employer (Employer”) when the fan shorted and sent 440 volts of electricity through Arneson’s hand, which exited through his foot (“the Work Injury”).

Arneson when to the emergency room for treatment. Within the next few days, he began suffering from mild heart palpitations. Almost two weeks later, Arneson went to the hospital for his heart palpitations and was diagnosed with hyperthyroidism and Atrial Fibrillation (“AFib”).

Arneson then brought a petition for workers’ compensation benefits arguing that the Work Injury caused his AFib and that he was permanently and totally disabled.

Arneson’s treating doctor, Dr. Holloway, provided an expert opinion that Arneson’s AFib was likely caused by his hyperthyroidism and the Work Injury.  Dr. Holloway acknowledged that Arneson’s hyperthyroidism could cause AFib itself. However, he also opined that electrical shocks like the Work Injury can cause heart arrythmias, such as AFib. Dr. Holloway did not provide an opinion on how commonly hyperthyroidism causes AFib or how commonly electrical injuries, like the Work Injury, cause AFib. He simply stated he believed both hyperthyroidism and the Work Injury causally contributed to Arneson’s AFib.

Employer countered by providing testimony from two non-treating experts. First, Employer presented the testimony of a cardiologist, Dr. Brody. Dr. Brody stated that he has rarely treated electrical injuries and that electric shock-induced AFib is extremely rare, occurring in less than 1% of cases based on his review of medical literature. In contrast, Dr. Brody testified that “the association” between hyperthyroidism and AFib “is a lot stronger” and more well accepted in the medical community. Dr. Brody then opined that the Work Injury was unlikely to have caused Arneson’s AFib, and the more likely cause was Arneson’s hyperthyroidism.  Employer also provided the testimony of Dr. Elkins. Dr. Elkins, like Dr. Brody, stated that it was statistically far more likely that hyperthyroidism caused Arneson’s AFib than an electrical shock like the Work Injury.

The Department of Labor (“Department”) found that the Work Injury was a major contributing cause of Arneson’s AFib and that he was permanently and totally disabled. Employer appealed arguing it was error for the Department to accept Dr. Holloway’s testimony that the Work Injury caused Arneson’s AFib when Employer presented unrebutted evidence that the Work Injury was statistically highly unlikely to have caused Arneson’s AFib.

The South Dakota Supreme Court (“Court”) rejected Employer’s argument and relied on a Minnesota case in support, stating “[a]n opinion based solely on statistical improbability ignores the fact that, by definition, improbable events do occur.” Arneson v. GR Mgmt., LLC, 2024 S.D. 61, ¶ 35, 13 N.W.3d 206, 217 (citing Ingram v. Syverson, 674 N.W.2d 233, 237 (Minn. Ct. App. 2004) (noting “medicine is an imperfect science and a plaintiff's symptoms may not always be proven by tests and statistics.”). The Court then found Dr. Holloway’s opinion was sufficient to show the Work Injury was a major contributing cause of Arneson’s AFib and affirmed the Department.

While the Court has still not defined “major contributing cause.” The Arneson opinion provides additional information on what “major contributing cause” is not. In this case, the Court was offered an opportunity to define major contributing cause in terms of probability and soundly rejected it. Employers should be aware of cases like this that continue to define the casual standard for compensable injuries.