Occasional premature beats in normal subjects are not clinically significant because they do not affect ventricular blood displacement and usually do not cause symptoms. However, if they occur in patients with organic heart disease, especially frequent and multiple premature beats, they may lead to more serious arrhythmias. The patient may feel panic and precordial discomfort, with a sudden, strong heartbeat followed by an interval of cardiac arrest. Some patients are very alarmed by this and often go to the hospital, describing a feeling of cardiac arrest or a sudden descent in an elevator. Frequent premature beats can cause a decrease in cardiac output, which often leads to fatigue, dizziness, chest tightness, distraction, lack of concentration, nervousness, and sometimes aggravates existing angina or heart failure.