Cardiac Resynchronization Therapy Update: Evolving Indications, Expanding Benefit?

Abstract

Cardiac resynchronisation therapy (CRT) is an effective intervention for appropriately selected patients with heart failure, but exactly how it works is uncertain. Recent data suggest that much, or perhaps most, of the benefits of CRT are not delivered by re-coordinating left ventricular dyssynchrony. Atrio-ventricular resynchronization, reduction in mitral regurgitation and prevention of bradycardia are other potential mechanisms of benefit that will vary from one patient to the next and over time. Because there is no single therapeutic target, it is unlikely that any single measure will accurately predict benefit. The only clinical characteristic that appears to be a useful predictor of the benefits of CRT is a QRS duration of >140 ms. Many new approaches are being developed to try to improve the effectiveness of and extend the indications for CRT. These include smart pacing algorithms, better pacing-site targeting, new sensors, multipoint pacing, remote device monitoring and leadless endocardial pacing. Whether CRT is effective in patients with atrial fibrillation or whether adding a defibrillator function to CRT improves prognosis awaits further evidence.

The effect of cardiac resynchronization without a defibrillator on morbidity and mortality: an individual patient data meta‐analysis of COMPANION and CARE‐HF

“…COMPANION required a PR interval >150 ms in order to increase the probability of biventricular capture; a requirement that may have enriched the population with patients more likely to benefit from atrio-ventricular resynchronization. 14,15 For COMPANION, patients were required to have had a hospital admission or equivalent for the treatment of heart failure between 1 and 12 months prior to enrolment but were excluded if the hospitalization occurred within less than 1 month. Neither hospitalization criterion was required for CARE-HF.…”

Os Benefícios Tecnológicos E O Potencial Risco De Complicações No Pós-Operatório Do Implante De Marcapasso

“…As indicações de classe II ocorrem quando uma anormalidade do nó sinusal é a causa provável dos sintomas, mas a correlação é difícil. A bradicardia sinusal <40 batimentos/min em um paciente com sintomas sugestivos de bradicardia constitui uma indicação de classe II para estimulação quando uma associação entre bradicardia e sintomas não pode ser definitivamente demonstrada 16 .…”

“…A síncope, nesse caso, pode estar relacionada ao componente vasodepressor da Coração em foco: explorando os aspectos fundamentais da saúde cardíaca síndrome. Em pacientes com síncope situacionaltosse, micção, entre outrosé importante evitar os gatilhos 16 .…”

“…Muitas doenças neuromusculares progressivas, como as distrofias musculares, são de especial preocupação, dado o curso imprevisível da doença e sua predileção pelo músculo cardíaco e fibrose dentro e ao redor do sistema His-Purkinje. Uma indicação de classe I para estimulação ocorre quando é observado um bloqueio AV de 2º ou 3º graus, independentemente dos sintomas 16 .…”

Smart Pacemaker: A Review

“…CRT is a costly therapy, which makes reimbursement difficult [ 25 ]. The relatively high complication rate associated with CRT as a result of the intricate structure of the coronary vein is another problem that affects its utilization in clinical practice.…”