When the heartbeat changes
The heart’s electrical system coordinates contraction of its chambers. An arrhythmia occurs when impulse formation or conduction changes. Some rhythm disturbances are harmless or temporary; others require investigation and treatment. Palpitations, fatigue, breathlessness, dizziness or fainting may be clues. An ECG recording helps establish which rhythm is responsible.
Slow and fast heart rates
A slow pulse can be normal during sleep or in trained athletes. A slow rate accompanied by fainting, marked fatigue or circulatory instability requires timely assessment. Fast rhythms can arise in the upper or lower chambers and have very different implications. Heart rate alone does not identify the cause.
Atrial fibrillation and AF-CARE
Atrial fibrillation can cause palpitations and reduced exercise tolerance, but may also be silent. The 2024 ESC AF-CARE approach combines management of associated conditions and risk factors, stroke prevention, rate or rhythm control, and continuing reassessment. The need for anticoagulation depends on thromboembolic risk and the wider clinical assessment, not simply on whether palpitations are present.1
Extra beats and palpitations
A skipped or unusually forceful beat may reflect an atrial or ventricular premature beat. Many do not indicate serious disease. Their frequency, associated symptoms, ECG characteristics and any underlying heart disease determine whether additional tests are needed. Palpitations should not automatically be attributed to anxiety before appropriate assessment.2
Fainting is not always an arrhythmia
Syncope is a temporary loss of consciousness caused by a transient reduction in blood flow to the brain, followed by spontaneous recovery. Reflex mechanisms, a fall in blood pressure on standing or cardiac disease may be responsible. The circumstances of the episode, warning symptoms, blood pressure and ECG guide investigation. Fainting during exercise, while lying down, with palpitations or in someone with known heart disease needs urgent attention.3
Tests, medicines and procedures
Depending on the presentation, investigations may include a Holter monitor, event recorder, implanted monitor, echocardiogram or electrophysiology study. Treatment is tailored to the documented rhythm and underlying condition. Catheter ablation is an option for selected tachyarrhythmias. A pacemaker treats particular slow rhythms; an implantable defibrillator can stop dangerous ventricular arrhythmias in selected patients. These devices serve different purposes.2
Related cardiovascular guides
Read about heart failure, high blood pressure and coronary artery disease, conditions that may form part of an individual rhythm assessment.
About Massimo Fioranelli · Cardiology and internal medicine · Clinical practice at Sanatrix, Rome
References and further reading
- ESC 2024: atrial fibrillation and AF-CARE.
- ESC 2022: ventricular arrhythmias and sudden cardiac death prevention.
- ESC 2018: syncope.
Reviewed 23 October 2026. Educational information does not replace individual medical assessment.