Effect of erythromycin on ventricular arrhythmias and ventricular repolarization in idiopathic long QT syndrome

Electrocardiogram (ECG) patterns recognized in patients with sudden death without structural abnormalities in the heart have guided cardiology over the last few decades towards a better understanding of the role of cardiac ion channels in physiology and in arrhythmogenicity in rare electrical diseases. The long QT syndrome became the paradigm for evaluating the association between specific ion channel abnormalities caused by mutations in genes encoding predominantly potassium and sodium channels and phenotypic ECG expression. Specific ECG patterns observed in long QT syndrome help in diagnosis and improve prognosis in patients affected by this disorder. Short QT syndrome also is characterized by specific patterns in repolarization morphology that relate to affected potassium current or calcium handling genes. Brugada syndrome and early repolarization syndrome are considered as J-wave syndromes, having some similarities in ECG features but with distinctive patterns associated with classical forms of these disorders. Spontaneous appearance of cove-type Brugada pattern is associated with a worse prognosis. Early repolarization patterns may also indicate prognosis in subjects with a prior history of cardiac arrest or ventricular arrhythmias or a family history of cardiac arrests. Catecholaminergic polymorphic ventricular tachycardia is another channelopathy without characteristic features in standard resting ECG but with characteristic polymorphic ventricular arrhythmias during catecholaminergic challenge (exercise test, stressing situations). Pre-excitation syndromes associated with sudden cardiac death are well recognized and current understanding of these disorders leads to a better therapy.

Download Full-text

Long QT syndrome: beyond making a diagnosis

Challenging Concepts in Congenital and Acquired Heart Disease in the Young ◽

10.1093/med/9780198759447.003.0014 ◽

2020 ◽

pp. 189-200

Author(s):

Gabrielle Norrish ◽

Juan Pablo Kaski

Keyword(s):

Long Qt Syndrome ◽

Ventricular Arrhythmias ◽

Beta Blockers ◽

Psychological Impact ◽

Population Screening ◽

Implantable Cardioverter Defibrillators ◽

Long Qt ◽

Arrhythmic Death ◽

Arrhythmic Event ◽

Qt Syndrome

Long QT syndrome (LQTS) is an uncommon, but important, cause of ventricular arrhythmias. The diagnosis is straightforward in symptomatic patients with marked QT prolongation on a resting 12-lead electrocardiogram (ECG). However, in many patients, the ECG findings are dynamic, and to make the diagnosis, clinicians need to be aware of suggestive features. The greatest challenge in managing these patients is risk stratification for a sudden arrhythmic event. Beta-blockers have been shown to reduce the risk for ventricular arrhythmias in all genotype-positive patients, regardless of 12-lead ECG findings. For patients in whom beta-blockers are contraindicated, left cardiac sympathetic denervation may be a useful therapy. Implantable cardioverter–defibrillators have a role to play in preventing sudden cardiac death, although their use should be balanced with associated complications and psychological impact. Population screening for LQTS remains controversial. Screening of first-degree relatives in sudden arrhythmic death syndrome is recommended, but population screening is not currently undertaken in the United Kingdom.

Download Full-text