Effects of right ventricular septal versus apical pacing on plasma natriuretic peptide levels

Background:

To investigate the contribution of right ventricular (RV) pacing sites to the cardiac function, this study compares plasma B-type natriuretic peptide (BNP) levels during RV septal and apical pacing in patients implanted with a pacemaker.

Materials and Methods and Results:

Seventy-four consecutive patients with indication for permanent pacing were included. To provide for the possibility of appropriate subgroup analyses, patients were stratified according to their pacing mode into two groups: Those with dual chamber DDD(R)/VDD pacemakers (41 patients, mean age 54.1±18.4 years), and those with single chamber VVI pacemakers (33 patients, mean age 60.6±18.4 years). A prospective single-blinded randomized design was used. Randomization (1:1 way) was between lead placement on the RV septum or RV apex and occurred during the implant in both groups. Compared to baseline, a significant decrease in BNP (429.8±103 pg/ml and 291.7±138 pg/ml, respectively) levels was observed during DDD(R) /VDD pacing after two months. In contrast, during VVI (R) pacing, a significant increase in BNP levels was observed (657.5±104 pg/ml and 889.5±139 pg/ml, respectively). To determine the impact of pacing sites on cardiac function, we assessed the changes in BNP levels in each group separately. Despite the significant difference in the pattern of changes between the two groups (P < 0.02), no significant changes were observed within groups regarding the acute effect of the pacing site (RV apex vs. RV septal) on BNP levels (P=NS).

Conclusions:

Our main result showed no significant differences between pacing sites and concluded that hemodynamic improvement could be substantially influenced by pacing mode, more than by pacing site.

Mid-term follow-up of patients with Brugada syndrome following a cardioverter defibrillator implantation: a single center experience

BACKGROUND

Brugada syndrome is an arrhythmogenic disease characterized by an ECG pattern of ST-segment elevation in the right precordial leads and an increase risk of sudden cardiac death. Risk stratification for the life-threatening arrhythmic events in Brugada syndrome is not yet established. In the present study, we report our experience in patients with Brugada syndrome, following an ICD implantation.

METHODS AND RESULTS

A total of 12 patients (11 men, 1 woman) with a mean age of 46.5+/-11.8 were studied. At diagnosis, 7 patients had syncope of unknown origin, 2 patients were asymptomatic, 2 patients were survivors of cardiac arrest, and 1 had documented clinical VT requiring direct cardioversion for termination. Age was similar between the symptomatic and asymptomatic patients (46.6+/-13 vs. 46+/-2.8, respectively). Two patients reported a family history of sudden cardiac death. In 3 patients, spontaneous coved-type ECG was found at baseline. In 9 patients, a class I antiarrhythmic drug administration unmasked the characteristic type I ECG. In 4 patients (2 symptomatic with syncope at presentation and 2 asymptomatic), who underwent PES, sustained polymorphic VT or VF was induced. VF was induced by single extrastimuli in 2 symptomatic patients (1 from RV apex and 1 from RVOT). In 2 asymptomatic patients, VF was induced by two and triple ventricular extrastimli (1 from RV apex and 1 from RVOT). None of them experienced an event during follow-up. No significant difference was found between symptomatic and asymptomatic patients (p=NS). The mean follow-up period for the entire study population was 27.83+/-11.25 months. During follow-up, 2 patients (one with prior cardiac arrest and another with syncope) had VF. Both of them had a type I ECG after provocation with a class I antiarrhythmic drug. None of them had undergone programmed ventricular stimulation. Five patients (41.7 %) had inappropriate ICD interventions during follow-up. The cause of inappropriate therapy was sinus tachycardia in 2 patients, AF in 2 patients and T wave oversensing in 1 patient.

CONCLUSION

Knowledge about Brugada syndrome is steadily progressing but there are still unanswered issues dealing with the risk stratification and the management of patients.

Prevalence and predictors of electrical storm in patients with implantable cardioverter-defibrillator

Identifying predictors of electrical storm in patients with implantable cardioverter-defibrillators (ICDs) could help identify those at risk and reduce the incidence of this emergency situation, which has a detrimental effect on mortality and morbidity in patients with ICDs. This retrospective study sought to determine the prevalence and predictors of electrical storm in patients with ICDs. One hundred sixty-two patients (126 men; mean age 58 +/- 13 years) who received ICDs from January 2001 to January 2005 were included in the study. Clinical, electrocardiographic, and ICD stored data and electrograms were collected and analyzed. Twenty-two patients (14%) developed electrical storm during a mean follow-up of 14.3 +/- 10 months. Using Cox multiple regression analysis, it was found that an ejection fraction <25% (p = 0.007), QRS width > or =120 ms (p = 0.002), and a lack of adjunctive angiotensin-converting enzyme inhibitor and beta-blocker therapy (both p < 0.001) were correlated with a greater probability of electrical storm. Adjunctive amiodarone and digoxin therapy, indication of ICD implantation, and age were not correlated with the occurrence of electrical storm during follow-up (all p = NS). In conclusion, electrical storm is not uncommon in patients with ICDs. Optimum medical therapy with beta blockers and angiotensin-converting enzyme inhibitors could reduce the occurrence of electrical storm, and this especially should be considered in those at greater risk for this complication (i.e., those with left ventricular ejection fractions <25% and QRS widths > or =120 ms).