Heart Failure Summit Review: cardiac re-synchronisation therapy in the failing heart

Progressive QRS Duration and Ventricular Dysfunction in Pediatric Patients with Chronic Ventricular Pacing

Pacemakers are a mainstay of therapy for patients with congenital and acquired heart block, but ventricular pacing is related to ventricular dysfunction. We sought to evaluate patient and device characteristics associated with ventricular dysfunction in pediatric patients with chronic ventricular pacing. This was a retrospective cohort of pediatric patients with heart block and chronic ventricular pacing. Patient, ECG, and device characteristics were analyzed to determine factors associated with ventricular dysfunction. Longitudinal ECG and echocardiogram parameters were obtained to track changes in QRS and systemic ventricular systolic function over time. In total, 82 patients were included (median age at implant 0.81 years). Over a follow-up time of 6.1 years, 18% developed ventricular dysfunction. Patients with dysfunction had greater current QRS duration (p = 0.002) compared to those with preserved function with a similar time from device implantation. There was no difference between lead location or age at device implantation. QRS duration increased with time from implant and the resultant ΔQRS was associated with ventricular dysfunction (p = 0.01). QRS duration >162 ms was associated with a 5.8 (2-9)-fold increased risk for dysfunction. Transvenous leads were associated with longer QRS duration with no difference compared to epicardial leads in development of ventricular dysfunction. This study demonstrated that the absolute paced QRS duration and Δpaced QRS were association with long-term ventricular dysfunction independent of how long a given patient was paced. Patients in high-risk categories may benefit from close echocardiographic monitoring. Whether permissive junctional rhythm or His bundle/biventricular pacing decreases the rate of dysfunction needs further study.

Successful pregnancies after transvenous cardiac resynchronization therapy in a woman with congenitally corrected transposition of the great arteries

Congenitally corrected transposition of the great arteries is a rare heart defect that can be associated with systemic ventricular dysfunction and conduction disturbances. The use of cardiac resynchronization therapy in patients with congenital heart disease is not fully established, and achievement of successful pregnancies after implantation of transvenous, biventricular system has never been described, and which resulted in a significant clinical improvement.

We describe a 33-year-old female with congenitally corrected transposition of the great arteries, who achieved six pregnancies and successful vaginal deliveries. The two last pregnancies were achieved after cardiac resynchronization therapy for systemic ventricular dysfunction and complete heart block. A congenital cardiac disease has been identified in only one offspring.

Perspective on precision medicine in paediatric heart failure

In 2015, President Obama launched the Precision Medicine Initiative (PMI), which introduced new funding to a method of research with the potential to study rare and complex diseases. Paediatric heart failure, a heterogeneous syndrome affecting approximately 1 in 100000 children, is one such condition in which precision medicine techniques may be applied with great benefit. Current heart failure therapies target downstream effects of heart failure rather than the underlying cause of heart failure. As such, they are often ineffective in paediatric heart failure, which is typically of primary (e.g. genetic) rather than secondary (e.g. acquired) aetiology. It is, therefore, important to develop therapies that can target the causes of heart failure in children with greater specificity thereby decreasing morbidity, mortality and burden of illness on both patients and their families. The benefits of co-ordinated research in genomics, proteomics, metabolomics, transcriptomics and phenomics along with dietary, lifestyle and social factors have led to novel therapeutic and prognostic applications in other fields such as oncology. Applying such co-ordinated research efforts to heart failure constitutes an important step in advancing care and improving the lives of those affected.

Rac1-PAK2 pathway is essential for zebrafish heart regeneration

P-21 activated kinases, or PAKs, are serine-threonine kinases that play important roles in diverse heart functions include heart development, cardiovascular development and function in a range of models; however, the mechanisms by which PAKs mediate heart regeneration are unknown. Here, we demonstrate that PAK2 and PAK4 expression is induced in cardiomyocytes and vessels, respectively, following zebrafish heart injury. Inhibition of PAK2 and PAK4 using a specific small molecule inhibitor impedes cardiomyocyte proliferation/dedifferentiation and cardiovascular regeneration, respectively. Cdc42 is specifically expressed in the ventricle and may function upstream of PAK2 but not PAK4 under normal conditions and that cardiomyocyte proliferentation during heart regeneration relies on Rac1-mediated activation of Pak2. Our results indicate that PAKs play a key role in heart regeneration.