Quarterly vs. yearly clinical follow-up of remotely monitored recipients of prophylactic implantable cardioverter-defibrillators: results of the REFORM trial.

AIMS: The rapidly increasing number of patients with implantable cardioverter-defibrillators (ICD) places a large burden on follow-up providers. This study investigated the possibility of longer in-office follow-up intervals in primary prevention ICD patients under remote monitoring with automatic daily data transmissions from the implant memory. METHODS AND RESULTS: Conducted in 155 ICD recipients with MADIT II indications, the study compared the burden of scheduled and unscheduled ICD follow-up visits, quality of life (SF-36), and clinical outcomes in patients randomized to either 3- or 12-month follow-up intervals in the period between 3 and 27 months after implantation. Remote monitoring (Biotronik Home Monitoring) was used equally in all patients. In contrast to previous clinical studies, no calendar-based remote data checks were performed between scheduled in-office visits. Compared with the 3-month follow-up interval, the 12-month interval resulted in a minor increase in the number of unscheduled follow-ups (0.64 vs. 0.27 per patient-year; P = 0.03) and in a major reduction in the total number of in-office ICD follow-ups (1.60 vs. 3.85 per patient-year; P < 0.001). No significant difference was found in mortality, hospitalization rate, or hospitalization length during the 2-year observation period, but more patients were lost to follow-up in the 12-month group (10 vs. 3; P = 0.04). The SF-36 scores favoured the 12-month intervals in the domains 'social functioning' and 'mental health'. CONCLUSION: In prophylactic ICD recipients under automatic daily remote monitoring, the extension of the 3-month in-office follow-up interval to 12 months appeared to safely reduce the ICD follow-up burden during 27 months after implantation. CLINICALTRIALSGOV IDENTIFIER: NCT00401466 (http://www.clinicaltrials.gov/ct2/show/NCT00401466).

Catheter ablation of electrical storm in patients with structural heart disease.

AIMS: Electrical storm (ES) adversely affects prognosis of patients and may become a life-threatening event. Catheter ablation (CA) has been proposed for the treatment of ES. Our goal was to evaluate the efficacy of CA ablation both in acute and long-term suppression of ES. METHODS AND RESULTS: Fifty consecutive patients with coronary artery disease (38), idiopathic dilated cardiomyopathy (5), arrhythmogenic right ventricular cardiomyopathy (6), and/or with combined aetiology (1) underwent CA for ES. Mean left ventricular ejection fraction (LVEF) was 29 ± 11%. All patients underwent electroanatomical mapping, and CA was performed to abolish all inducible ventricular arrhythmias. The ES was suppressed by CA in 84% of patients. During the follow-up of 18 ± 16 months, 24 patients had no recurrences of any ventricular tachycardia (VT; 48%). Repeated procedure was necessary to suppress the recurrent ES in 13 cases (26%). Statistical analysis revealed that low LVEF (22 ± 3 vs. 31 ± 12%; P < 0.001), increased LVend-diastolic diameter (72 ± 9.1 vs. 64 ± 8.9 mm; P = 0.0135), and renal insufficiency (P < 0.001) were the univariate predictors of early mortality or necessity for heart transplantation. Recurrence of ES despite previous CA procedure was associated with a higher risk of death or heart transplant during follow-up (P < 0.05). CONCLUSION: Catheter ablation is effective in acute suppression of ES and often represents a life-saving therapy. In the long term, it prevents recurrences of any VT in about half of the treated patients.

The relationship between right ventricular pacing voltage and QRS complex duration.

Compared to the natural electrical activation of the myocardium through the His-Purkinje system, right ventricular pacing is associated with prolonged QRS complex duration, thereby impeding the synchronicity of contractions. In left ventricular pacing, a higher pacing voltage decreases the QRS complex duration. The aim of our study was to describe the relation between the right ventricular pacing voltage and the QRS complex duration. Fourteen patients (73.6 +/- 7.6 years) with AV block and implanted pacemakers were paced at a frequency of 100 bpm with various pacing voltages. A signal-averaged QRS vector length was calculated at each degree of pacing voltage. The changes in the QRS complex duration were measured as a relative shift of the terminal region of the vectorcardiographic QRS complex (end-shift) and its most prominent peak (peak-shift) using the cross-correlation method. The nonlinear relationship between stimulation voltage and QRS duration was observed with the highest impact of stimulation voltage changes near the threshold value. The fourfold increase in the stimulation voltage above the threshold caused QRS complex shortening by 3.7 +/- 2.1 ms (range 0.19-7.76 ms). Similar peak- and end-shift responses to altered stimulation energy demonstrated that the acceleration of depolarization occurred in the initial portion of the QRS complex. Older electrodes exhibited smaller and more linear changes in the QRS complex duration.

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.

Ventricular activation patterns during different pacing modes. An insight from electroanatomical mapping.

BACKGROUND: Biventricular pacing (BiV) is employed as the current standard for cardiac resynchronisation therapy. Other pacing modalities have been proposed as alternatives; however, data on changes in electrical activation sequence caused by pacing from various sites are limited. AIM: To describe changes in activation patterns during different ventricular pacing modes in patients with chronic heart failure. METHODS: A total number of 20 patients (mean age 59.6+/-8 years) with chronic heart failure, intraventricular conduction abnormality (QRS >130 ms) or complete AV block were studied. Endocardial activation maps of both ventricles (CARTOTM, Biosense-Webster) were obtained during spontaneous rhythm and biventricular (BiV, n=9), right ventricular bifocal (BiF, n=7) and single-site left ventricular (LV, n=4) pacing. The following parameters were assessed: activation pattern, total LV endocardial activation time (LVAT) and electrical interventricular delay (IVD). RESULTS: Right ventricular apical pacing was associated with the longest LVAT (145+/-24 ms). On the contrary, both BiV and BiF pacing shortened LVAT with BiV being superior in the degree of LVAT reduction (89+/-13 vs 103+/-10 ms, p<0.05). BiV pacing also significantly shortened IVD and modified the LV activation sequence in a complex manner. Such changes were not observed during BiF pacing. In the presence of fusion with spontaneous activation, single-site LV pacing was comparable to BiV pacing. CONCLUSIONS: Among the different pacing modes, BiV pacing and single-site LV pacing with fusion resulted in the most pronounced changes in ventricular activation that appear to be a prerequisite for successful resynchronization of both ventricles.

Surgical ablation of post-infarction ventricular tachycardia guided by mapping in sinus rhythm: long term results.

OBJECTIVE: Some patients after myocardial infarction have an increased risk of malignant ventricular tachyarrhythmias (VTA) or sudden cardiac death. The aim of the study was to evaluate long-term results of surgical ablation of an arrhythmogenic substrate guided by simplified intraoperative mapping of pathological ventricular electrograms during sinus rhythm. METHODS: The study population consisted of 77 patients (9 women; mean age 62.4+/-8.5 years) with previous Q-wave myocardial infarction and at least one documented episode of sustained VT/VF more than one month after the last infarction. The left ventricular ejection fraction was 31.3+/-8.8%. All but eight patients had clinical indication for concomitant coronary artery bypass surgery. All underwent preoperative electrophysiologic study. Intraoperative epicardial and endocardial mapping during sinus rhythm was performed using a multielectrode with 16 bipolar electrodes in combination with a multichannel recording system. Myocardial regions revealing fractionated, low amplitude signals lasting > or =130 ms were surgically excised or cryoablated. All surviving patients were restudied within one to two weeks after surgery using identical programmed electrical stimulation protocol. RESULTS: Five (6.5%) patients died in the perioperative (30-days) period. In the remaining cohort, inducibility of any sustained VTA after surgical procedure was observed in 21 subjects (29.2%). An implantable cardioverter-defibrillator (ICD) was implanted in these patients. Recurrence of sustained VTA was documented during follow-up period in two patients who were noninducible after the surgery (at the month 10 and 22, respectively), and both received ICD as well. No patient died of sudden cardiac death. In 14 ICD patients, no significant VTA was documented during the mean follow-up of 37.3+/-23.2 months. Altogether, 61 from the 72 patients surviving the surgery (84.7%) remained free of spontaneous recurrences of VTA during the follow-up. CONCLUSIONS: Surgical ablation of an arrhythmogenic substrate guided by simplified intraoperative mapping in normothermic heart during sinus rhythm appears to be both safe and efficacious procedure that prevents recurrences of VTA in a substantial proportion of patients.

Percutaneous extraction of a fractured permanent pacemaker lead with no free end.

From various points of view abandoned or displaced permanent pacemaker leads should be extracted in indicated cases using a broad spectrum of catheter-based techniques. We describe a relatively easy extraction procedure of almost the whole pacemaker lead, which broke near the pulse generator and migrated into right-heart chambers; so both ends were indwelling. The described procedure was undertaken using a simple homemade nitinol-based extractor.

Percutaneous extraction of a severed and frayed permanent pacing lead.

From the point of view of established practice, redundant permanent pacing leads have been abandoned or extracted using various catheter-based procedures. An unusual complication was caused by failed surgical lead extraction resulting in electrode severing and wire unbraiding with subsequent induction of electric interaction between the metallic, noninsulated part of the lead fragment and the defibrillating electrode. This interaction was sensed and detected by the ICD system. A modified catheter-based extraction procedure is described.

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.

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.

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

UNLABELLED: 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.

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.