1. The resulting condition of an employee who:
(a) Has a preexisting condition from a cause or origin that did not arise out of or in the course of the employee’s current or past employment; and
(b) Subsequently sustains an injury by accident arising out of and in the course of his or her employment which aggravates, precipitates or accelerates the preexisting condition,
Ê shall be deemed to be an injury by accident that is compensable pursuant to the provisions of chapters 616A to 616D, inclusive, of NRS, unless the insurer can prove by a preponderance of the evidence that the subsequent injury is not a substantial contributing cause of the resulting condition.
2. The resulting condition of an employee who:
(a) Sustains an injury by accident arising out of and in the course of his or her employment; and
(b) Subsequently aggravates, precipitates or accelerates the injury in a manner that does not arise out of and in the course of his or her employment,
Ê shall be deemed to be an injury by accident that is compensable pursuant to the provisions of chapters 616A to 616D, inclusive, of NRS, unless the insurer can prove by a preponderance of the evidence that the injury described in paragraph (a) is not a substantial contributing cause of the resulting condition.