How does life expectancy change with ventricular tachycardia?
Ventricular tachycardia can significantly impact life expectancy. The prognosis varies widely depending on several factors, such as the underlying heart condition, the overall health, and the treatment received.
Long term prognosis of treated patients with no detectable heart disease is generally good. Early treatment is beneficial and prolongs the patient’s life [1]. However, in patients with heart disease, the prognosis can be worse. For instance, in patients with left ventricular function impairment, the percentage of sudden cardiac death was higher, especially with a low ventricular ejection fraction [2].
Treatment can significantly improve life expectancy. Nevertheless, it's important to note that with time ventricular tachycardia can lead to tachycardia-induced cardiomyopathy. It is a condition characterized by structural changes in the heart and significant left ventricular dysfunction. This condition can be reversible in only some cases after the arrythmia is controlled [3].
The impact on life expectancy is different from patient to patient. However, an event of ventricular tachycardia is linked with a decrease in life expectancy. Especially in older people the occurrence of this fast heartbeat condition is linked to a higher 5 years mortality [4].
What is life expectancy?
Life expectancy refers to the average number of years a person is expected to live. It is based on the year of their birth, their current age, and other demographic factors including gender and location. It is a statistical measure used to understand the overall health status of a population.
Life expectancy varies across different regions and populations. For instance, life expectancy at birth is 78 years in developed countries, 72 in Latin America, 70 in China, 63 in Eastern Europe and 51 in Africa [5]. In the United States, life expectancy reached a record high of 78.7 years in 2010 [6]. However, it's important to note that these are averages and they are different within the populations. For example, in Chicago life expectancy across the 77 community areas was in some 68.2 years low and others 83.3 years high [6].
What is arrythmia?
An arrhythmia is a condition characterized by an abnormal heart rhythm. It occurs when the electric impulses, that are needed for the heart contractions, are disturbed. Arrythmia can be fast or slow with regular or irregular patterns. Some of them don't cause symptoms, so it's possible to have one and not realize it. Due to that, arrythmias are often diagnosed after palpations or fainting during a stressful situation or exercise [7].
Tachycardia
Normally the heart of an adult at rest should not beat faster than 100 beats per minute (BPM). Situations in which the heart beats faster than that are referred to as tachycardia.
What is ventricular tachycardia?
Ventricular tachycardia (VT) is a serious rhythm disturbance. It is a very fast heart rate that can originate from any part of the myocardium or conduction system below the atrioventricular node. On the ECG VT presents with a wide QRS complex (more than 120ms) and a heart rate greater than 100 BPM with at least three ventricular heartbeats in a row [8, 9].
Ventricular tachycardia can last for a few seconds or for much longer. Medically they are referred to as non-sustained and sustained ventricular tachycardia, respectively. It may not cause symptoms, but when symptoms do occur, they may include light-headedness, dizziness, and fainting. Because of the fast heart beat there is little time for the blood to fill the heart. Due to this development, VT eventually leads to low blood pressure and ventricular fibrillation or cardiac arrest. As the chamber shivers or becomes unable to contract, blood is not pumped out of the heart. A stop of blood flow makes this abnormal heart rhythm fatal if not resuscitated [9].
Causes of ventricular tachycardia
There are many causes of VT but there are a few known mechanisms. For example, the ionic imbalance or general changes in the environment of the cells of the heart. One of the most common aetiologies, which causes such changes, is myocardial infarction of the ventricle, like in coronary heart disease [10]. Another aetiology is structural heart abnormality. For instance, when a large tumour arises in the septum there is a high risk of VT [11].
Patients with a rare ventricular noncompaction are susceptible to developing VT. It is a condition where the heart muscle appears spongy [12].
In some cases, VT can occur without any detectable cause, a condition known as idiopathic VT. They arise mostly on the ground of electrophysiological mechanism changes. Those appear especially in conditions like cardiomyopathies [13, 14]. Other idiopathic VT can originate from various parts of the heart without structural changes. For instance, it can come from the right ventricular outflow tract (RVOT) [15, 16], the mitral annulus [17], or the left ventricular outflow tract (LVOT) [18].
Also, genetic mutations can lead to it. For example, a somatic cell mutation in the G protein subunitalphai2. It lead to biochemical imbalance of within the heart cells and has been identified as a cause of some idiopathic ventricular tachycardia [19].
Symptoms of ventricular tachycardia
Ventricular tachycardia can sometimes occur without any noticeable symptoms. This can happen especially if it lasts only for a short period. However, when symptoms do occur they can be quite distressing.
One of the most common symptoms of ventricular tachycardia is palpitation (sensation of the heart racing or pounding) [20]. Patients may experience dizziness. This can be accompanied by a feeling of light-headedness [9]. Another common symptom is fatigue. This is a general feeling of tiredness or exhaustion that can be quite debilitating [9]. Chest pain is also frequently reported. This pain can be quite severe and may be mistaken for a heart attack [20, 9]. However, it has to be remembered that an ischemic event can be a cause of VT. Another symptom is shortness of breath, referred to as dyspnoea. It makes it difficult to carry out normal daily activities [9]. Other less common symptoms include weakness, nausea, diaphoresis (excessive sweating), and flushing [20].
Within a short time, ventricular tachycardia can lead to a drop in blood pressure and tissue perfusion. This can lead to fainting, cardiac arrest and is fatal if not treated promptly [9].
However, the severity and type of symptoms can vary greatly from one individual to another. Additionally, they are influenced by the heart rate and underlying heart condition [20].
Diagnosis and treatment of ventricular tachycardia
Diagnosis of VT is primarily based on electrocardiography (ECG). Most commonly a 12-lead ECG performed is. In the case of temporary VT cardiac telemetric monitoring can be used to catch VT occurring live[21, 22]. Other diagnostic tests may include a cardiac MRI (CMRI) for detailed images of the heart or transesophageal echocardiography. These methods are used to look at the structure of the heart [9].
The treatment of VT is guided by patient symptoms. Crucial is the risk of sudden death estimated by the VT mechanism and underlying cardiac structure [23]. In patients with idiopathic VT and structural heart disease catheter ablation is performed[24]. A positive aspect of this procedure is a high success rate (> 90%) with few procedural complications [25].
In coronary artery disease and ventricular arrythmias with ventricular disfunction an implantable cardioverter defibrillator (ICD) is indicated. When it comes to pharmacotherapy, antiarrhythmic drugs are used to prevent frequent recurrences. Examples of such drugs are amiodarone/sotalol and beta-blockers. In some cases, a hybrid approach combining all these therapeutic modalities is often needed. Good information is that the survival rates in patients with specific VT syndromes such as right ventricular outflow VT, left ventricular fascicular VT, and left ventricular outflow VT is excellent with drugs [26].
