Hypertension or diabetes, both risk factors for stroke, did not change significantly risk of stroke for people with PVCs. It is possible that PVCs identified those at risk of stroke with blood pressure and impaired glucose tolerance on a continuum of risk below conventional diagnostic thresholds for hypertension and diabetes. Those in ARIC study with any PVC had risk of heart failure increased by 63% and were > twice as likely to die from coronary heart disease (CHD). Risk was also higher for people with or without baseline CHD.In the Niigata study of 63,386 people with a 10-year follow-up period, subjects with PVC during a 10-second recording had triple the risk of atrial fibrillation of those without PVCs, independently of these risk factors: age; male sex; high simple body mass index (a possible signifier of obesity); hypertension (systolic and diastolic blood pressure within certain abnormal limits); and diabetes.Reducing very frequent PVC (>20%) by antiarrhythmic drugs or by catheter ablation significantly improves heart performance.Recent studies have shown that those subjects with extremely frequent PVCs (several thousand a day) can develop dilated cardiomyopathy. In these cases, if the PVCs are reduced or removed (for example, via ablation therapy) the cardiomyopathy regresses. Epidemiology
Single PVCs are common in healthy persons. When 24-hour ambulatory monitoring is used, up to 80 percent of apparently healthy people have occasional PVCs. Rates vary by age with extremely rare for those under the age of 11 and extremely common in those older than 75 years.
Women may be more aware of PVCs at the time of the menstrual period.Premature ventricular contractions may be associated with underlying heart disease, and certain characteristics are therefore elicited routinely: the presence of signs of heart disease or a known history of heart disease (e.g. previous myocardial infarction), as well as heart disease or sudden cardiac death in close relatives. PVCs and palpitation associated with syncope (transient loss of consciousness) or provoked by exertion are also concerning. Physical examination is focused on identifying evidence of underlying heart disease. Causes
Premature ventricular contractions occur in healthy persons of any age, but are more prevalent in the elderly and in men. In a very significant proportion of people they occur spontaneously with no known cause.Some possible underlying causes of PVCs include:

Non-cardiac causes
Adrenaline excess
Anemia
Catecholamine excess
Certain medicines such as tricyclic antidepressants, digoxin, sympathomimetics, aminophylline
Chemical (electrolyte) abnormalities in the blood (for example hypokalemia (low blood potassium), which can occur in those taking diuretics ("water pills") and hypomagnesaemia (magnesium deficiency)). Contact with the carina (trachea/bronchi) when performing medical suctioning stimulates vagus nerve
Drugs/substances such as:Amphetamines
Alcohol
Caffeine
Cocaine
Nicotine
Theobromine
Hypercapnia (CO2 poisoning)
Hypertension (high blood pressure)
Hyperthyroidism
High blood calcium
Hypoxia and/or hypercapnia
Lack of sleep/exhaustion
Sarcoidosis
Smoking
Stress
Anxiety

Cardiac causes
Any structural heart disease which alters electrical conduction pathways due to tissue alterations
Cardiomyopathy, hypertrophic or dilated
Myocardial infarction
Myocarditis
Myocardial contusion
Mitral valve prolapse

Pathophysiology
Normally, impulses pass through both ventricles almost at the same time and the depolarization waves of the two ventricles partially cancel each other out in the ECG.