Contraction delay of the RV outflow tract in patients with Brugada syndrome is dependent on the spontaneous ST-segment elevation pattern

Value of mechanical dyssynchrony as assessed by radionuclide ventriculography to predict the cardiac resynchronization therapy response

AIMS

To assess the value of mechanical dyssynchrony measured by equilibrium radionuclide angiography (ERNA) in predicting long-term outcome in cardiac resynchronization therapy (CRT) patients.

METHODS AND RESULTS

We reviewed 146 ERNA studies performed in heart failure patients between 2001 and 2011 at our institution. Long-term follow-up focused on death from any cause or heart transplantation. Phase images were computed using the first harmonic Fourier transform. Intra-ventricular dyssynchrony was calculated as the delay between the earliest and most delayed 20% of the left ventricular (LV) (IntraV-20/80) and inter-ventricular dyssynchrony as the difference between LV- and right ventricular (RV)-mode phase angles (InterV). Eighty-three patients (57%) were implanted with a CRT device after ERNA. Median follow-up was 35 [21-50] months. Twenty-four events were observed during the first 41 months. Median baseline ERNA dyssynchrony values were 28 [3 to 46] degrees for intraV-20/80 and 9 [-6 to 24] degrees for interV. Comparing survival between CRT and non-CRT patients according to dyssynchrony status, log-rank tests showed no difference in survival in patients with no ERNA dyssynchrony (P = 0.34) while a significant difference was observed in ERNA patients with high level of mechanical dyssynchrony (P = 0.004).

CONCLUSION

ERNA mechanical dyssynchrony could be of value in CRT patient selection.

Brugada syndrome: an update

More than 20 years have passed since the description of Brugada syndrome as a clinical entity. The original case series depicted patients who all had coved ST-segment elevation in the right precordial leads, associated with a high risk of sudden death and no apparent structural heart disease. As subsequent registry data were published, it became apparent that the spectrum of risk is wide, with the majority of patients classified as low risk. Two consensus documents have been published that will continue to be updated. Despite intense research efforts, many controversies still exist over its pathophysiology and the risk stratification for sudden death. Management continues to be challenging with a lack of drug therapy and high complication rates from implantable cardioverter defibrillators. In this review, we highlight the current state-of-the-art therapies and their controversies.

Arrhythmogenesis in Brugada syndrome: impact and constrains of current concepts

Brugada syndrome (BrS), an inherited arrhythmogenic disease first described in 1992, is characterized by ST segment elevations on the electrocardiogram in the right precordium and by a high occurrence of arrhythmias including the life-threatening ventricular tachycardia/fibrillation. Knowledge of the underlying mechanisms of formation of arrhythmogenic substrate in BrS is essential, namely for the risk stratification of BrS patients and their therapy which is still restrained almost exclusively to the implantation of cardioverter/defibrillator. In spite of many crucial findings in this field published within recent years, the final consistent view has not been established so far. Hence, BrS described 20 years ago remains an actual topic of both clinical and experimental studies. This review presents an overview of the current knowledge related to the pathogenesis of BrS arrhythmogenic substrate, namely of the genetic basis of BrS, functional consequences of mutations related to BrS, and arrhythmogenic mechanisms in BrS.

Brugada syndrome: two decades of progress

Two decades ago, a series of 8 idiopathic ventricular fibrillation patients who each had an abnormal ECG (right bundle branch block with coved-type ECG), but otherwise had normal hearts were described by Brugada and Brugada. Since then, the clinical entity has become known as Brugada syndrome (BS). Shortly thereafter, mutations of the SCN5A gene that encodes for the α-subunit of the sodium channel were found, galvanizing the field of ion channelopathies following in the footsteps of the breakthrough in long QT syndrome. Over the past 20 years, extensive research in this field has produced major progress toward better understanding of BS and the gaining of knowledge of the genetic background, pathophysiology and new management. Two consensus reports were published to help define the diagnostic criteria, risk stratification and management of BS patients. However, there are controversies. In this review, we will share our experiences of BS patients in Thailand and discuss advances in many aspects of the syndrome (ie, genetics and pathophysiology) and some of these pertinent controversies, as well as new treatment of the syndrome with catheter ablation.