Causes of and Risk Factors for Arrhythmias
Conditions or Events that Affect the Heart
Arrhythmias are frequently associated with conditions or events that affect the structure or function of the heart including (MayoClinic 2011a; NHLBI 2011a; Hebbar 2002a,b; Brown 2010):
- Coronary artery disease
- The narrowing of arteries in coronary artery disease can lead to arrhythmias (NHLBI 2011a; Haugaa 2011; MayoClinic 2011c; Ghuran 2011).
- Congestive heart failure
- Congestive heart failure (deterioration of the heart’s ability to pump blood) is associated with a high risk of sudden cardiac death from arrhythmia (Nessler 2007; Johns Hopkins 2012).
- History of heart attack
- Some form of heart rhythm abnormality is present in over 90% of individuals who have had a heart attack (Hebbar 2002a; Merck Manual 2008).
- Infectious myocarditis
- Infections that damage the heart (ie, infectious myocarditis) have been associated with some types of arrhythmia (Friedman 1994; Maury 2008).
- A damaged or dysfunctional heart muscle (ie, cardiomyopathy) can cause arrhythmias (Nava 1992; Ji 2004).
- Congenital heart defects
- Being born with certain heart malformations may lead to disturbances in the heart rhythm (Rekawek 2007; MayoClinic 2011a; Haugaa 2011).
Indirect and Non-Cardiac Risk Factors for Arrhythmias
In addition to inherited and/or acquired structural/functional heart problems, several other risk factors have well-established relationships with arrhythmias. These risk factors (such as cigarette smoking) may beget arrhythmias either by contributing to chronic structural or functional heart abnormalities over time, or temporarily altering the biochemistry of the body in such a way as to trigger a transient arrhythmia (such as from excessive intake of stimulants like caffeine).
- Imbalance of electrolytes
- Imbalanced blood levels of electrolytes such as sodium or potassium alter the excitability of the heart muscle and the conduction of the electrical impulses, and may lead to arrhythmias (MayoClinic 2011a).
- High blood pressure
- High blood pressure is thought to increase the thickness and stiffness of the left ventricular walls over time, which changes the way in which electrical impulses travel through the heart (MayoClinic 2011a).
- Obesity may increase risk of developing arrhythmia and lead to cardiac problems in several ways: it can affect the heart indirectly, by increasing lipid levels, blood pressure, and glucose intolerance, or directly, by increasing the blood volume, which elevates cardiac output and causes thickening of the heart muscle in the left ventricle (Mathew 2008; MayoClinic 2011d).
- The mechanisms that explain the link between smoking and arrhythmia are complex. It is thought that nicotine promotes the formation of excess fibrous tissue in the heart and increases susceptibility to stress hormones. Other constituents of tobacco smoke, such as carbon monoxide, along with oxidative stress, appear to play additional roles. Moreover, smoking causes coronary artery disease and chronic obstructive pulmonary disease, which independently predispose to arrhythmia (D’Alessandro 2012).
- Alcohol abuse
- Chronic alcohol use may lead to disease/dysfunction of the cardiac muscle and cause the heart to beat less efficiently (Podrid 1987; Witchel 2003; Barnes 2010; MayoClinic 2011a).
- Acute emotional and psychological stress may trigger potentially deadly arrhythmias (Taggart 2011; Hansson 2004; Ziegelstein 2007).
- Uncontrolled diabetes increases the risk of developing coronary artery disease and hypertension. Also, episodes of low blood sugar may trigger arrhythmia (MayoClinic 2011a).
- Thyroid dysfunction
- Atrial fibrillation occurs in 10-15% of patients with hyperthyroidism, and low serum thyroid stimulating hormone (TSH) concentrations are an independent risk factor for atrial fibrillation (Fazio 2004; Jayaprasad 2005).
- Stimulants such as caffeine and certain prescription medications may lead to various types of arrhythmias. Certain illegal drugs, such as methamphetamine and cocaine, may lead to arrhythmias or sudden death due to ventricular fibrillation (MayoClinic 2011a; Hebbar 2002a).
- Oxidative stress
- Oxidative stress has been implicated in the development of ventricular tachycardia and fibrillation, particularly in situations wherein the blood supply to the heart is temporarily interrupted and then restored (eg, following a heart attack) (Wolin 2005).
- Performance sports
- Athletes are at increased risk for developing atrial fibrillation, a relatively common arrhythmia in the athletic community; it is more frequently seen in middle-aged than young athletes. Autonomic nervous system alterations, systemic inflammation, and increased atrial size are some of the factors thought to be involved (Sorokin 2011; Turagam 2012; Maisel 2003).
- Certain medications
- Certain medications including digoxin (Lanoxin®), tricyclic antidepressants, and antipsychotics can sometimes cause arrhythmias (Hebbar 2002a). Other compounds that can induce arrhythmia are some antiemetics, antibacterial agents, anesthetics, and bronchodilators. Even certain anti-arrhythmia medications such as flecainide (Tambocor®), dofetilide (Tikosyn®), and sotalol (Betapace®) may induce or worsen other types of arrhythmia (Podrid 1987; Witchel 2003; Barnes 2010; MayoClinic 2011a).