Sudden Heart Palpitations: What Causes Them and How to Diagnose

Experiencing a sudden, forceful heartbeat or feeling of palpitations may indicate transient tachycardia. It's advisable to undergo an electrocardiogram (ECG), both in a relaxed, resting state and during an episode of palpitations, to compare the results. A 24-hour Holter monitor can also be used to assess the severity of arrhythmias or myocardial ischemia and help reach a clear diagnosis.

Common Causes of Sudden Heart Palpitations

When a person experiences a sudden episode of heart palpitations, several underlying conditions may be responsible. These include:

1. Premature Contractions (Premature Beats)

Premature contractions are among the most common causes of palpitations. If they occur infrequently, they typically don't require treatment with antiarrhythmic medications. However, if they are frequent, it's important to investigate the underlying cause. Conditions such as thyroid dysfunction, anemia, electrolyte imbalances, or coronary artery disease with significant stenosis can lead to secondary arrhythmias. Identifying and treating the root cause is essential for effective management.

2. Atrial Fibrillation (AFib)

In cases of paroxysmal atrial fibrillation, the resting ECG may appear normal. However, during an episode, the ECG can reveal irregular QRS complexes, an irregularly irregular rhythm, absence of P waves, and the presence of varying F waves. These findings confirm the presence of AFib, a type of irregular and often rapid heart rate that can increase the risk of stroke and other heart-related complications.

3. Paroxysmal Supraventricular Tachycardia (PSVT)

This condition is characterized by sudden onset and termination of a rapid heartbeat. Episodes can last from a few seconds to several minutes, and in rare cases, even days. Once the episode subsides, the heart typically returns to a normal rhythm without any lingering symptoms such as chest tightness or palpitations. PSVT is often diagnosed through event monitoring or a Holter study during an active episode.