Arrhythmias appear to be a common complication in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) and may contribute to an increased risk of death, according to a recently published study in Cardiovascular Revascularization Medicine.
Understanding cardiac arrhythmias
The heart’s atria and ventricles usually contract in a rhythmic, coordinated manner to properly fill with and pump out blood. An arrhythmia is an irregular heartbeat caused when the contraction of the artria and ventricles becomes uncoordinated.
Arrhythmias can result in uneven blood distribution and may cause symptoms such as palpitations, loss of consciousness (syncope) and sudden death. Furthermore, some arrhythmias can lead to blood stagnation within the heart, which may result in the formation of blood clots. These clots can then block blood vessels and cause strokes.
Read more about ATTR-CM signs and symptoms
Arrhythmia in ATTR-CM
The study’s authors aimed to determine the incidence of arrhythmias and their associated risk factors in patients with ATTR-CM. To achieve this, they analyzed data from all patients with ATTR-CM treated at their hospital between 2010 and 2013.
The results showed that atrial fibrillation (AF) — an arrhythmia in which the atria contract rapidly and irregularly — was present in approximately 60% of patients. Researchers found that the coexistence of peripheral neuropathy, carpal tunnel syndrome and an increased left atrial volume index significantly increased the risk of AF.
More concerningly, the authors found that over 6% of patients had experienced episodes of sustained ventricular tachycardia (VT). VT is a life-threatening arrhythmia in which chaotic ventricular contractions lead to circulatory collapse and cardiac arrest. It is a common cause of sudden cardiac death. Risk factors associated with an increased risk of VT included prolonged QRS duration on electrocardiogram and increased left ventricular volume.
The clinical impact of arrhythmias in cardiac amyloidosis
Statistical analysis showed no significant correlation between atrial arrhythmias and increased mortality.
Sudden cardiac death occurred in 18 patients, representing nearly 10% of the total sample. Around 30% of the patients in the study received an implantable cardioverter-defibrillator (ICD). An ICD is a device designed to monitor heart rhythm and deliver electrical shocks to restore normal rhythm when VT is detected. Criteria for implantation include a history of VT, unexplained fainting and low ventricular ejection fraction.
The authors remarked that ICD implantation did not appear to improve survival in this patient cohort.
“Whereas sustained VT was associated with a significantly higher risk of mortality in patients with cardiac amyloidosis, ICD implantation did not demonstrate a survival benefit in our cohort,” the authors wrote.
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