Is a heart rate of 135 bpm dangerous?

A heart rate of 135 bpm is somewhat dangerous and carries a high risk of malignant arrhythmias—such as ventricular fibrillation or atrial fibrillation—due to the excessively rapid heartbeat. Prolonged tachycardia is also detrimental to cardiac function and requires prompt, active treatment. We recommend visiting the Department of Cardiology at a hospital for comprehensive evaluation, including tests such as: complete blood count (CBC), electrocardiogram (ECG), chest X-ray, echocardiography, carotid artery ultrasound, 24-hour Holter monitoring, and cardiac enzyme assays—to identify the underlying cause and guide targeted therapy.