Prognosis
A significant proportion of those with CPVT will experience a life-threatening abnormal heart rhythm, with estimates of this risk ranging from 13 to 20% over the course of 7–8 years. Life-threatening arrhythmias are more likely to occur if CPVT has been diagnosed in childhood, if a person with CPVT does not take beta blockers, and if arrhythmias occur on exercise testing despite taking beta blockers.During treatment with nadolol, the preferred beta blocker for the treatment of CPVT, event rates have been estimated to be 0.8% per year. In patients treated with beta blockers, life-threatening arrhythmias are more likely if a person had already survived a cardiac arrest, had a syncope, or are carriers of disease-causing mutations affecting the highly conserved terminal portion of RYR2 gene, called the C-terminal domain (amino acids 4889–4969). Epidemiology
CPVT is estimated to affect 1 in 10,000 people. Symptoms from CPVT are typically first seen in the first or second decade of life, and more than 60% of affected individuals experience their first episode of syncope or cardiac arrest by age 20. Syncope during exercise or strong emotion should be considered a red flag, as it is a characteristic of the disease. Lastly, a small number of patients may present later in life, and genetic testing in these patients frequently fails to identify a causative gene. History
In 1960, Norwegian cardiologist Knut Berg published a report on three sisters who had blackouts during exercise or emotional stress in what is now recognised as the first description of CPVT.
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited genetic disorder that predisposes those affected to potentially life-threatening abnormal heart rhythms or arrhythmias. The arrhythmias seen in CPVT typically occur during exercise or at times of emotional stress, and classically take the form of bidirectional ventricular tachycardia or ventricular fibrillation. Those affected may be asymptomatic, but they may also experience blackouts or even sudden cardiac death. CPVT is caused by genetic mutations affecting proteins that regulate the concentrations of calcium within cardiac muscle cells. The most commonly identified gene is RYR2, which encodes a protein included in an ion channel known as the ryanodine receptor; this channel releases calcium from a cells internal calcium store, the sarcoplasmic reticulum, during every heartbeat. CPVT is often diagnosed from an ECG recorded during an exercise tolerance test, but it may also be diagnosed with a genetic test. The condition is treated with medication including beta-adrenoceptor blockers or flecainide, or with surgical procedures including sympathetic denervation and implantation of a defibrillator. It is thought to affect as many as one in ten thousand people and is estimated to cause 15% of all unexplained sudden cardiac deaths in young people. The condition was first defined in 1978, and the underlying genetics were described in 2001. Signs and symptoms
Although individuals with CPVT may not experience any symptoms, the most commonly reported symptoms are blackouts or sudden loss of consciousness, referred to as syncope.