Alterations in the expression of genes related to contractile function and hypertrophy of the left ventricle in chronically paced patients from the right ventricular apex.

AIM: Long-term right ventricular apical (RVA) pacing may lead to left ventricular (LV) remodelling and heart failure. This study assessed changes in the expression of genes regulating LV contractile function and hypertrophy, after permanent RVA pacing and investigated whether such changes proceed or even predict LV remodelling. METHODS AND RESULTS: We enrolled 52 consecutive patients (age 79.1 ± 7.7 years, 34 males) who underwent pacemaker implantation for bradycardic indications: Group A, 24 individuals with atrioventricular conduction disturbances and group B, 28 patients with sinus node disease. In group A, peripheral blood mRNA levels of gene sarcoplasmic reticulum calcium ATPase decreased at 3, 6, and 12 months' follow-up, while α-myosin heavy chain (MHC) decreased and ß-MHC increased until 6 months follow-up. In this group, 25% of patients demonstrated significant LV remodelling. At 4 years, LV end-systolic diameter increased from 29.67 ± 3.39 mm at baseline to 35.38 ± 4.22 mm, LV end-diastolic diameter increased from 50 ± 4.95 to 56.71 ± 5.52 mm, and ejection fraction declined from 63.04 ± 10.22 to 52.83 ± 10.81%. Early alterations in gene expression were associated with a deterioration in LV function and geometry that became apparent months later. In group B, echocardiographic indexes and mRNA levels of the evaluated genes demonstrated no statistically significant changes. CONCLUSIONS: Permanent RVA pacing in patients with preserved ejection fraction is associated with alterations in the expression of genes regulating LV contractile function and hypertrophy, measured in the peripheral blood. These alterations are traceable at an early stage, before echocardiographic changes are apparent and are associated with LV remodelling that becomes evident in the long term.

Biventricular pacing in paced patients with normal hearts.

Right ventricular apical (RVA) stimulation, although beneficial in the treatment of symptomatic bradycardia, has proven detrimental in a substantial percentage of pacemaker recipients, leading to iatrogenic deterioration of left ventricular structure and function. Alternative right ventricular pacing sites appeared advantageous but their superiority has not been proven. Biventricular stimulation is effective in reducing ventricular dyssynchrony in subgroups of heart failure patients, improving their functional capacity, morbidity, and mortality. Therefore, it seems logical that this pacing strategy, by eliminating ventricular dyssynchrony, could play an important role in preventing the deleterious effects of chronic RVA stimulation in patients with normal hearts who undergo cardiac pacing for bradycardia indications. Preliminary investigations have yielded encouraging results, but further studies with harder endpoints such as quality of life, morbidity, and mortality are necessary to clarify the potentially advantageous effect of biventricular stimulation in paced patients with normal hearts.

Novel pacing algorithms: do they represent a beneficial proposition for patients, physicians, and the health care system?

Modern pacemakers are enriched with several embedded algorithms, aiming at achieving a more "physiological" pacing, at reducing pacing-related costs and at maximizing the physician's and the patient's convenience. Though some of these algorithms offer proven benefits, the efficacy of others is still under serious dispute. Herein are presented some of the most important algorithms integrated in modern pacemakers, together with an overview of the currently available literature concerning their efficacy and safety, as well as their impact on the economics of health care systems.

Appropriate management of syncope in a patient with hypertrophic cardiomyopathy: rationale behind long-term cardiac rhythm monitoring.

We describe the case of a patient with hypertrophic cardiomyopathy who had recurrent syncopal episodes, the cause of which remained unexplained despite a thorough evaluation. Two years after his first evaluation, an implantable loop recorder revealed asymptomatic episodes of advanced second degree atrioventricular block while the patient was awake. Although a permanent pacemaker was implanted, the patient continued to suffer syncopal episodes, during which the pacemaker recorded episodes of ventricular tachycardia. Accordingly, the device was upgraded to an implantable cardioverter-defibrillator.