AZ HB2679

Strengthens the legal presumption that heart-related, perivascular, or pulmonary injuries, illnesses, or deaths in firefighters are occupational diseases eligible for workers' compensation

Raises the standard for employers to rebut the presumption from "preponderance of the evidence" to "clear and convincing evidence" showing the condition was solely caused by a documented, pre-existing nonoccupational condition

Explicitly prohibits using age, family history, fitness level, lifestyle factors, speculation, statistical risk factors, or post-event medical findings as evidence to rebut the presumption

Establishes that cardiac events occurring while on duty, during emergency response, training, or department-directed activity (or within 24 hours after) are automatically considered occupational diseases

Expands the definition of "heart-related" conditions to include myocardial infarction, acute coronary syndrome, cardiac arrhythmias (including atrial fibrillation and ventricular tachycardia), syncope of cardiac origin, and structural abnormalities aggravated by occupational stress