Decrease in plasma B-type natriuretic peptide early after initiation of cardiac resynchronization therapy predicts clinical improvement at 12 months

BACKGROUND

Decrease in neurohormonal activation during pharmacotherapy for chronic heart failure (CHF) is associated with haemodynamic and clinical improvement. We tested the hypothesis that changes in neurohormonal activation after initiation of cardiac resynchronization therapy (CRT) predict its long-term clinical effect.

METHODS

The study group included 43 patients with CHF (37 males, mean age 62+/-9 years, NYHA class 3.2+/-0.4, QRS duration 195+/-24 ms) who underwent successful implantation of a CRT system. Pharmacotherapy remained stable during the first 3 months of follow-up. Plasma levels of B-type natriuretic peptide (BNP) and big endothelin-1 (big ET-1) were evaluated before and 3 months after implantation. Clinical, echocardiographic and exercise parameters were monitored for a mean period of 25.8+/-6.7 months.

RESULTS

At 12 months of follow-up 13 non-responders were identified (no improvement in NYHA class (n=10), urgent heart transplantation (n=2) and death due to progressive heart failure (n=1)). CRT resulted in a significant reduction in neurohormone levels (BNP 345.4+/-346 vs. 267.7+/-320.8 pg/ml, p<0.01, big ET-1 3.11+/-1.50 vs. 2.50+/-1.56 fmol/ml p<0.05), especially in responders. Percentage change in BNP level was a stronger predictor of long-term clinical improvement than clinical, echocardiographic and exercise parameters at 3 months of follow-up.

CONCLUSIONS

Percentage change in plasma BNP levels from baseline to 3 months was the strongest predictor of long-term response to CRT and may have potential to predict outcome.

Optimization of right ventricular lead position in cardiac resynchronisation therapy

BACKGROUND

The benefit of biventricular pacing (BiV) may be substantially affected by optimal lead placement.

AIM

To evaluate the importance of right ventricular (RV) lead positioning on clinical outcome of BiV.

METHODS AND RESULTS

A total of 99 patients with symptomatic heart failure and implantation of BiV system were included. Position of the left-ventricular (LV) lead was selected based on timing of local endocardial signal within the terminal portion of the QRS complex. RV lead was preferably positioned at the midseptum (n=74, RVS group) where the earliest RV endocardial signal was recorded. A subgroup of patients had RV lead placed in the apex (n=25, RVA group). NYHA class, maximum oxygen-uptake (VO(2)max), LV end-diastolic diameter (LVEDD, mm) and ejection fraction were assessed every third month. A trend towards greater improvement in NYHA class and significant increase in VO(2)max was present in the RVS group. Moreover, a significant decrease in LVEDD (DeltaLVEDD) was observed in the RVS group only (-3.4+/-6.5 mm versus +1.7+/-6.4 mm in RVA group at 12 months, p=0.004). No significant correlation between the degree of DeltaLVEDD and QRS narrowing induced by BiV was found. LVEDD reduction was predominantly present in dilated cardiomyopathy.

CONCLUSIONS

Midseptal positioning of the RV lead appears to promote reverse LV remodelling during cardiac resynchronisation therapy.

The Spectrum of Inter- and Intraventricular Conduction Abnormalities in Patients Eligible for Cardiac Resynchronization Therapy

Although cardiac resynchronization therapy (CRT) has clearly demonstrated its clinical benefit in patients with congestive heart failure (CHF) and intraventricular conduction abnormalities, selection of eligible patients and/or optimal pacing site are still a matter of debate. The aim of the study was to analyze the spectrum of conduction abnormalities in CRT candidates. A total of 26 patients (mean age 62 +/- 9 years) with CHF and conduction disturbances (QRS > or = 130 ms) were studied. The underlying heart disease was dilated cardiomyopathy (DCM) (n = 12) or coronary artery disease (CAD) (n = 14). High density, left ventricular endocardial activation maps were constructed using an electroanatomic mapping system (CARTO). Based on endocardial activation patterns, left ventricular conduction abnormalities were classified as left bundle branch block (LBBB) (n = 9), nonspecific intraventricular conduction disturbances (n = 10), and the bifascicular block (n = 7). In DCM patients the endocardial activation sequences corresponded with a 12-lead ECG pattern with a homogeneous spread of activation wavefront and the latest activation laterally (LBBB) or anteriorly (bifascicular block), respectively. CAD patients presented with variable activation patterns that reflected the location of the postinfarct scar, and the 12-lead ECG was less predictive. Although there was a trend for longer QRS durations for DCM subjects (170 +/- 23 vs 156 +/- 23 ms, P = NS), left ventricular activation time was significantly longer in the CAD group (115 +/- 21 ms vs 134 +/- 23 ms, P < 0.05). CRT candidates represent a broad spectrum of conduction abnormality patterns with variable inter- and intraventricular activation delays. CAD subjects have more pronounced intraventricular conduction abnormality. The standard ECG is less reliable in the characterization of complex conduction abnormalities.

Technical Aspects of Implantation of LV Lead for Cardiac Resynchronization Therapy in Chronic Heart Failure

The goal of this study was to analyze total procedural and fluoroscopic time during initial experience with implantation of LV lead in a single center, and to assess the performance of electrophysiologically-guided approach for cannulation of the coronary sinus (CS) in a subsequent period. Over an initial period of 29 months, a total of 46 attempts to implant biventricular pacing system were revised. During the first phase, only one type of LV electrode was available for three implanters (11 attempts). The second phase covered their early experience with other stylet-controlled LV leads (10 attempts). Additional LV leads including the over-the-wire design were available in the third phase and 25 attempts were done by he most experienced implanter. In a period of advanced experience, 92 implant procedures performed by four implanters using an electrophysiologically-guided approach to CS cannulation were revised. In the first period, success rates for different phases reached 70%, 90%, and 96%, respectively. Significant decrease in both procedural and fluoroscopic times was achieved with increased experience (Phase I: 247.1 +/- 104.5 minutes and 31.2 +/- 34.3 minutes, Phase II: 219.4 +/- 85.6 minutes, and 22.9 +/- 19.1 minutes, Phase III: 116.4 +/- 89.9 minutes and 6.6 +/- 4.4 minutes, respectively, P < 0.05). Advanced experience with electrophysiologically-guided approach to CS cannulation allowed achievement of this target within a reasonable amount of time (15.4 +/- 16.3 minutes) and with minimum fluoroscopic time (2.1 +/- 2.9 minutes). In conclusion, both individual learning curve and technical advances significantly influence success rate, procedural, and fluoroscopic times for biventricular system implantation. Electrophysiologically-guided approach makes cannulation of the CS a highly reproducible procedure that requires minimum fluoroscopic time.

[Treatment of ventricular arrhythmias]

The term ventricular arrhythmia denotes various disorder in the cardiac rhythm--from isolated monomorphic ventricular extrasystoles to ventricular flutter and fibrillation. The choice of therapy of ventricular arrhythmias is primarily based on prognostic aspects. Ventricular tachycardias represent the main cause of sudden cardiac death, which is responsible for more than 60% of all deaths for cardial causes. In the industrially advanced countries the ventricular tachyarrhythmias represent more than 90% of cases based on coronary disease. The prevention of sudden death is directed particularly to prevention and therapy of ischaemic heart disease. The prognostic classification divides ventricular tachycardias into benign, potentially malignant and malignant ones, respectively. The benign arrhythmias do not require therapy. In the malignant (i.e. potentially lethal) ventricular tachyarrhythmias the implantation of cardioverter-defibrillator represents the most efficient treatment. In the largest group of patients with potentially malignant ventricular arrhythmias the present risk-oriented stratification enables a partial identification of persons with markedly increased risk of sudden death. They may be considered for preventive implantation of cardioverter-defibrillator. In some patients the therapeutic effect is reached by application of various therapeutic methods including a combination of pharmacological and non-pharmacological therapy, which also includes catheterization or surgical ablation of the arrhythmogenic substrate. A corresponding attention should be devoted to the basal cardial disease.

Coincidence of idiopathic ventricular outflow tract tachycardia and atrioventricular nodal reentrant tachycardia

BACKGROUND

Tachycardia-induced tachycardia appears to be a relatively rare condition. In such cases an important question arises whether catheter ablation of one arrhythmia may prevent the occurrence of another. This paper reviews single-centre experience with coincident idiopathic outflow tract ventricular tachycardia (VT) and atrioventricular (AV) nodal reentry tachycardia (AVNRT), and strategy of treatment.

METHODS AND RESULTS

Seven of 46 patients (15%) with clinically documented idiopathic outflow tract VT were found to have reproducibly inducible AVNRT at the time of an electrophysiological study. There were two men and five women (mean age 35+/-9 years, range 20-44) without structural heart disease. During the study, AVNRT spontaneously triggered VT in three cases. Radiofrequency catheter ablation of the slow pathway did not suppress subsequent inducibility of VT in any of them. Successful catheter ablation of VT did not prevent clinical recurrence of AVNRT in one patient, and led to transition of VT into typical AVNRT in another.

CONCLUSION

Coincidence of idiopathic outflow tract VT and AVNRT was found in 15% of cases of clinically documented idiopathic VT. Catheter ablation of one arrhythmia substrate did not prevent inducibility or clinical recurrence of the other. These data support the strategy of performing catheter ablation of both arrhythmia substrates during one session.

Clinical application of electroanatomical mapping in the characterization of "incisional" atrial tachycardias

Scar tissue after surgical procedures for congenital heart disease may create a complex arrhythmogenic substrate and expose patients to the risk of "incisional" tachycardia. We report the usefulness of electroanatomical mapping in the characterization of reentrant circuits and identification of sites of successful radiofrequency (RF) ablation.

METHODS

Electroanatomical mapping was used to draw activation maps of the right atrium in 6 men and 4 women (mean age 45 +/- 13.7 years) with 21 atrial tachycardias after corrections of atrial septal defects (n = 6) or tetralogy of Fallot (n = 4). The critical isthmus of reentrant circuits was ablated by RF energy.

RESULTS

Macroreentrant circuits were localized on the posterolateral wall of the right atrium in all cases. Scar tissue in that region often contained several pathways that allowed induction of different tachycardias. Interruption of all slow conducting pathways successfully abolished all inducible tachycardias. The cavotricuspid isthmus participated in a figure-of-eight reentrant circuit or in a typical flutter circuit in 6 patients. RF ablation was successful in all but one patient, without significant complications.

CONCLUSION

Electrocanatomical mapping allows the precise description of macroreentrant circuits and the identification of all slow conducting pathways. It is a powerful tool for the planning of ablation lines, navigation of ablation catheter, and verification of conduction block.

Catheter ablation of ventricular tachycardia following myocardial infarction using three-dimensional electroanatomical mapping

One challenge encountered during catheter ablation of postinfarction ventricular tachycardia (VT) is the inducibility of multiple VT morphologies associated with variable hemodynamic instability. The clinical usefulness and safety of a three-dimensional electroanatomical mapping in guiding radiofrequency (RF) catheter ablation of VT, used in parallel with a multichannel recording system, was studied in 28 men (mean age = 63.8 +/- 10.6 years, mean left ventricular ejection fraction = 28% +/- 9%). Three-dimensional voltage maps of the left ventricle were obtained in sinus rhythm with annotation of areas of fractionated or late potentials, zones of slow conduction and/or dense scar with no pacing capture at 10 mA. RF lesions were created either in sinus rhythm or during hemodynamically stable VT within reconstructed critical zones of the circuit. A total of 82 VTs were induced (mean = 2.9 +/- 1.0/patient). Hemodynamically unstable clinical VTs were induced in 5 patients, and clinical or nonclinical unstable VT in 14. Clinical VT was rendered noninducible in 24/28 (85.7%) patients, and monomorphic VT was eliminated in 16/28 (57.1%) patients. The mean procedural time was 258 +/- 82 minutes, and fluoroscopic exposure 13.5 +/- 8.8 minutes. During a mean follow-up period of 10.6 +/- 6.4 months, catheter ablation was repeated in 6 patients for VT recurrences. No significant complications occurred except for a transient cerebral ischemic attack in one patient. In conclusion, electroanatomical mapping assisted the successful and safe catheter ablation of both mappable and nonmappable VTs in a significant proportion of patients after myocardial infarction.

Radiofrequency catheter ablation of postinfarction ventricular tachycardia from the proximal coronary sinus

Optimum strategy for radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) after inferior wall myocardial infarction (MI) that originates from the posteroseptal process of the left ventricle is not known. We describe a case report of a 57-year-old man who developed recurrent post-MI VT with ECG morphology consistent with this type of VT (i.e., left bundle branch block pattern with predominant R waves from V2 to V6 and left-axis deviation). Endocardial mapping and entrainment during VT demonstrated a critical isthmus of the reentrant circuit in the proximal coronary sinus. RF application terminated VT and rendered it noninducible.

Recurrent pericardial chest pain: a case of late right ventricular perforation after implantation of a transvenous active-fixation ICD lead

A 36-year-old woman with a history of recurrent syncopal episodes presumably due to ventricular tachyarrhythmia in mitral valve prolapse underwent implantation of a transvenous ICD system. During a 23-month follow-up, she developed recurrent pericardial chest pain with pericardial friction rub. The first episode of chest pain occurred without any detectable change in pacing or sensing parameters. The second episode was associated with an increase in pacing threshold and drop in intracardiac signal amplitude. Right ventricular perforation was suspected fluoroscopically and confirmed by right ventriculography. This case report emphasizes the key steps in the diagnosis of this rare complication of an ICD implantation.

[Surgical therapy of serious heart rhythm disorders]

The author summarizes his experience with operations in 40 patients. Twenty-one were operated on account of W-P-W syndrome, 9 on account of ventricular tachycardia due to IHD and in 10 patients an automatic defibrillator was implanted. None of the patients died and the results of surgery are satisfactory.

[Tiracizine in the treatment of ventricular arrhythmia (preliminary study)]

Tiracizine a new antiarrhythmic drug class Ia was tested in a open crossover study in a group of 46 patients with more than 2500 ventricular extrasystoles per 24 hours or with ventricular arrhythmias III or a higher Lown class. The authors revealed a statistically significant drop of ventricular extrasystoles and a significant reduction of arrhythmias class IV of Lown's classification with a general shift of arrhythmias to lower classes. Improvement by at least one class occurred in 63%, deterioration without clinical impact in 11%. The drug does not have a clinical effect on haemodynamics. Side-effects of an anticholinergic type were recorded in 13% and a toxic allergic exanthema was observed in 6.5%. Tiracizine extends the spectrum of membrane antiarrhythmic drugs. Its effectiveness is similar as that of propafenon.

Changes in ventricular effective refractory periods after two extrastimuli and ventricular electrical instability

Using programmed stimulation with one and three extrastimuli delivered in the right ventricular apex, we compared the effective refractory period (ERP) during sinus rhythm (ERP-SR) and during the third extrastimulus (ERP-S3) in patients without ventricular tachycardias (control group, n = 87) and in patients with documented ventricular tachycardia (VT group, n = 76). The protocol was not completed to determine ERP-S3 in one patient in the control group and in 15 patients in the VT group. We observed a significantly greater change (i.e., shortening) in ERP after two extrastimuli in the VT group compared with patients without VT (delta ERP = 45 +/- 20 msec in the control group and 70 +/- 16 msec in the VT group, P < 0.001). This electrophysiological phenomenon, along with conduction delay, may play an important role in VT induction.

[How should ventricular arrhythmia be treated?]

Antiarrhythmic therapy of ventricular arrhythmias in patients after myocardial infarction, even if it reduces the incidence of arrhythmias, does not influence the mortality, as demonstrated in the American CAST study where the most effective antiarrhythmic drugs class Ic, encainide and flecainide, were used. As a result of proarrhythmogenic action therapy may even enhance the risk. The authors present a classification of ventricular arrhythmias and recommend therapeutic strategies. They draw attention to the fact that the proarrhythmogenic action may develop in the early as well as in the late stage of treatment. Beta-blockers still remain the only group of drugs which markedly reduce the incidence of sudden death in patients after myocardial infarctions.