Premature Ventricular Contractions (PVCs)

What happens during a PVC

Normally each heartbeat starts in the sinus node and travels in an orderly way from the atria to the ventricles. A PVC is an extra impulse that fires from a spot in the ventricle before the next normal beat. Because the ventricles contract early, before they have filled, the PVC itself pumps little blood and is often not felt. The pause that follows lets the ventricles overfill, so the next normal beat is stronger, which many people feel as a thump.

Patterns

• isolated PVCs: single extra beats
• bigeminy: every other beat is a PVC
• trigeminy: every third beat
• couplets: two PVCs in a row
• non-sustained ventricular tachycardia: three or more in a row. See paroxysmal ventricular tachycardia

Symptoms

• a skipped or missed beat
• a flip-flop, flutter or hard thump in the chest or neck
• brief lightheadedness
• a cough-like sensation
• anxiety about the heartbeat
• fatigue or reduced exercise tolerance if very frequent

Many people have PVCs without noticing them. Symptoms are often more noticeable at rest, when lying on the left side, or at night.

Causes and triggers

Common triggers

• caffeine and energy drinks
• alcohol and binge drinking
• nicotine and vaping
• stress, anxiety and adrenaline
• lack of sleep
• dehydration
• stimulants: decongestants, asthma inhalers, ADHD medicines, cocaine and amphetamines
• intense exercise in some people

Medical causes

• low potassium (hypokalemia) or low magnesium
• overactive thyroid
• anemia
• sleep apnea
• heart disease: coronary artery disease, previous heart attack, cardiomyopathy, valve disease, myocarditis
• inherited conditions, such as arrhythmogenic cardiomyopathy and long QT syndrome
• certain medicines, such as digoxin and some antidepressants

In many healthy people, especially those with PVCs from the right ventricular outflow tract, no specific cause is found.

Are PVCs dangerous?

Usually not. In a structurally normal heart, PVCs are generally benign. They are more concerning when:

• the PVC burden is high, often 10 to 15% or more of all heartbeats on a 24-hour monitor, which can cause PVC-induced cardiomyopathy, a weakening of the heart that is usually reversible with treatment
• they occur with cardiomyopathy, heart failure or a previous heart attack
• they come in runs or cause fainting
• they increase with exercise rather than disappear
• there is a family history of sudden death or inherited heart disease

Diagnosis

• ECG: captures PVCs if present at the time and shows their shape, which suggests where they come from.
• Holter monitor (24 to 48 hours) or patch monitor (up to 2 weeks): counts PVCs and measures the burden.
• Echocardiogram: checks heart structure and pumping strength.
• Blood tests: potassium, magnesium, thyroid function and blood count.
• Exercise stress test: shows whether PVCs suppress or increase with exertion.
• Cardiac MRI: if heart muscle disease is suspected.

Treatment

Reassurance and lifestyle

For most people with a normal heart and modest PVC burden, knowing PVCs are harmless reduces anxiety, which itself reduces symptoms. Helpful steps:

• cut back on caffeine, alcohol and nicotine
• improve sleep and manage stress
• stay hydrated
• treat sleep apnea
• review medicines and supplements

Medicines

• beta-blockers (such as metoprolol) or non-dihydropyridine calcium channel blockers (verapamil, diltiazem) reduce symptoms
• antiarrhythmic drugs such as flecainide (only with a structurally normal heart) or amiodarone in selected cases

Catheter ablation

Ablation targets the spot where PVCs originate and eliminates them in a high proportion of patients, especially those from the outflow tracts. It is recommended for:

• frequent PVCs causing cardiomyopathy
• symptomatic PVCs not controlled by or not tolerating medicines
• PVCs that trigger ventricular fibrillation

Outlook

Most people with PVCs live normal lives. PVC-induced cardiomyopathy often recovers once PVCs are suppressed. In people with structural heart disease, PVCs are a marker for monitoring and treatment of the underlying condition.

Frequently asked questions

What are premature ventricular contractions?

PVCs are extra heartbeats that start early in the heart's lower chambers, disrupting the normal rhythm. They feel like a skipped beat or a thump. They are very common and usually harmless in people with healthy hearts.

What causes PVCs?

Common triggers include caffeine, alcohol, nicotine, stress, lack of sleep, dehydration and stimulant medicines. Medical causes include low potassium or magnesium, thyroid disease, anemia, sleep apnea and heart disease. Often no specific cause is found.

Are PVCs dangerous?

In most people with structurally normal hearts, PVCs are benign. They are more concerning if they are very frequent, occur with heart disease, come in runs, cause fainting, or worsen with exercise. A cardiologist can assess your risk with an ECG, monitor and echocardiogram.

How many PVCs a day is too many?

A PVC burden above about 10 to 15% of all heartbeats on a 24-hour monitor, often more than 10,000 to 20,000 PVCs a day, can weaken the heart over time. Lower numbers are usually harmless unless there is heart disease.

How can I stop PVCs?

Reducing caffeine, alcohol and nicotine, improving sleep, managing stress and staying hydrated often help. If PVCs remain bothersome or frequent, beta-blockers, calcium channel blockers or catheter ablation can reduce or eliminate them.