Thyroid disease in cats is linked to heart disease and a fast heartbeat in conjunction with any other symptoms of thyroid problems is cause for a trip to the vet. Once the hyperthyroidism is treated, your cat's heart rate should return to normal.
Stress reaction â some studies have found that paranoia is more common in people who have experienced severe and ongoing stress â for example, prisoners of war. How stress can trigger paranoia is unclear.
Heart disease. Researchers have long suspected that the stressed-out, type A personality has a higher risk of high blood pressure and heart problems. We don't know why, exactly. Stress can directly increase heart rate and blood flow, and causes the release of cholesterol and triglycerides into the blood stream. It's also possible that stress is related to other problems -- an increased likelihood of smoking or obesity -- that indirectly increase the heart risks.