Cardiac implantable electronic device remote monitoring in a large cohort of patients and the need for planning.

Aim: The remote monitoring (RM) of cardiac implantable electronic devices (CIED) is standard of care. We describe an organizational and projection RM workload model. Methods: At the time of the analysis (2015), 3995 CIED patients were followed-up; 1582 (40.5%) with RM. All RM transmissions (Tx) have been gathered in five event types. Results: We received 10,406 Tx, classified as: 128 (1.2%) red alerts, 141 (1.3%) atrial fibrillation episodes, 1944 (18.6%) yellow alerts, 403 (3.9%) lost Tx (disconnected/noncompliant patients) and 7790 (75.0%) Tx 'OK' (un-eventful Tx). At the time of 100% of remote CIED managed, we can expect a total of 25,990 Tx/year. Conclusion: We provide a descriptive analysis of remote monitoring management and workload estimation in a large cohort of CIED patients.

Single-center experience with wearable cardioverter-defibrillator as a bridge before definitive ICD implantation.

BACKGROUND: The wearable cardioverter-defibrillator (WCD) has been approved for patients with poor left ventricular ejection fraction (LVEF) who are at risk of sudden arrhythmic death for a limited period but are not candidates for a definitive implantable cardioverter-defibrillator (ICD). The present study sought to retrospectively analyse our single-centre experience. METHODS AND RESULTS: All consecutive WCDs applied between April 2017 and September 2018 in our centre were enrolled. An exercise test was performed in all patients in order to evaluate the absence of false detection of ventricular arrhythmias by the device. A total of 16 patients (57.7 ± 14.8 years old; 75% males) were taken into consideration for the analysis. Mean LVEF was 32 ± 11% at diagnosis and 42 ± 10% at last follow-up (mean, 3.1 ± 1.7 months; median, 3 months). At the end of the "wearing period" 11/16 patients (69%) did not have ICD implant indications and only 5 (31%) underwent ICD implantation. Neither appropriate nor appropriate shocks occurred during the follow up. CONCLUSIONS: The WCD represents a useful tool to bridge a temporarily increased risk for sudden cardiac death. The proportion of patients with an improvement of LVEF> 35% beyond the WCD-application period was considerable.

Safety steps for a non-fluoroscopic approach in right-sided electrophysiology procedures: A point of view.

BACKGROUND: Electro-anatomic 3D mapping systems enable the fluoroscopy (FL) exposure to be reduced. In right-heart supraventricular tachycardia (SVT) procedures, FL could potentially be avoided. Our aim was to discuss some steps focusing on safety. METHODS AND RESULTS: The patient cohort comprised 70 consecutive SVT patients who underwent electrophysiologic (EP) catheterization. FL was routinely avoided in all cases (54.2% males, age 57.2 ±â€¯13.3 years): 51 ablations and 19 EP study procedures. The Carto®3 (Biosense Webster) mapping system was used in 17/70 cases (24.3%), and the EnSite Precision™ (Abbott) system in the remaining 53/70 (75.7%). The mean procedure time was 94.1 ±â€¯33.2 min; no FL was used. No major complications occurred. Acute procedural success was achieved in all 51 patients who underwent ablation. Over 3-month follow-up, arrhythmia recurred in 1 patient. There were no significant differences in procedural times between the two mapping systems, except for the time dedicated to the full geometry creation, which was longer for the EnSite Precision™ system: 10 min (8.5-15 IQR) vs 8 min (5-10 IQR) for the Carto® system (p < 0.001) mainly due to the sub-diaphragmatic navigation. The following procedural steps were considered critical in order to safely avoid FL use: "loop" advancing of catheters, the use of a fixed intracardiac reference, His signal landmark centered maps and the careful acquisition of sub-diaphragmatic extracardiac geometry. CONCLUSIONS: A routine zero X-ray approach by means of electro-anatomic 3D mapping systems is safe and effective in right-atrium procedures. Some ad-hoc discussed procedural steps may enhance safety.

Multicentre comparison Of shock efficacy using single-vs. Dual-coil lead systems and Anodal vs. cathodaL polarITY defibrillation in patients undergoing transvenous cardioverter-defibrillator implantation. The MODALITY study.

PURPOSE: An optimal active-can lead configuration during implantable cardioverter defibrillator (ICD) placement is important to obtain an adequate defibrillation safety margin. The purpose of this multicenter study was to evaluate the rate of the first shock success at defibrillation testing according to the type of lead implant (single vs. dual coil) and shock polarity (cathodal and anodal) in a large series of consecutive patients who received transvenous ICDs. METHODS: This was a multicenter study enrolling 469 consecutive patients. Single- versus dual-coil leads and cathodal versus anodal polarity were evaluated at defibrillation testing. In all cases, the value of the energy for the first shock was set to 20 J less than the maximum energy deliverable from the device. RESULTS: A total of 469 patients underwent defibrillation testing: 158 (34 %) had dual-coil and 311 (66 %) had single-coil lead systems configuration, 254 (54 %) received anodal shock and 215 (46 %) received cathodal shock. In 35 (7.4 %) patients, the shock was unsuccessful. No significant differences in the outcome of defibrillation testing using single- versus dual-coil lead were observed but the multivariate analysis showed an increased risk of shock failure using cathodal shock polarity (OR 2.37, 95 % CI 1.12-5.03). CONCLUSIONS: Both single- and dual-coil transvenous ICD lead systems were associated with high rates of successful ICD implantation, and we found no significant differences in ventricular arrhythmias interruption between the two ICD lead systems configuration. Instead, anodal defibrillation was more likely to be successful than cathodal defibrillation.

Late atrial tachycardia following pulmonary vein isolation: analysis of successful discrete ablation sites.

BACKGROUND: The role of additional left atrial linear lesions performed during pulmonary vein isolation (PVI) to prevent atrial tachycardias (ATs) is not yet clear. OBJECTIVE: To analyse successful ablation sites of late-onset post-PVI AT, and to understand whether additional ablation lines at mitral isthmus and left atrium (LA) roof could have been useful in preventing these jatrogenic ATs. METHODS: From March, 2002 to August, 2008, 366 patients underwent PVI alone for drug-refractory atrial fibrillation (AF). Twenty-six (7.1%) of these patients developed late AT during follow-up, and were referred for ablation. Successful discrete ablation sites were analysed. In no patient the index AT was terminated by a linear lesion in mitral isthmus or LA roof. RESULTS: Twenty-seven ATs were mapped; mean CL was 261 ± 71.6 ms. In 3/26 patients (11.5%), mapping was unsuccessful, while 23/26 (88.5%) patients underwent a successful procedure (24 AT morphologies in 23 patients - 3/24 were mapped as mitral isthmus, and 1/24, as LA roof-dependent AT). Among the 24 successfully mapped ATs, 17/24 (70.8%) displayed a macroreentrant activation and the remaining 7/24 (29.1%), a focal pattern. Finally, in 22/26 (84.6%) patients, ATs were no more inducible. At a mean f/u of 22.4 ± 12.2 months, 23/26 (88.4%) patients remained AT-free (antiarrhythmic drugs prescribed in 5/26, 19.2% patients for AF prevention). CONCLUSIONS: In our case series, less than one-fifth of late-onset post-PVI ATs were mapped as mitral isthmus- or LA roof-dependent circuits.

Straight screw-in atrial leads "J-post shaped" in right appendage versus J-shaped systems for permanent atrial pacing: a safety comparison.

BACKGROUND AND OBJECTIVES: The reliability of active-fixation atrial leads has been compared with that of passive-fixation leads; comparisons have also been made between straight and J-shaped screw-in lead systems. However, few data are available on procedural and short-term safety. This retrospective study compared the procedural safety of non-pre-shaped screw-in leads with that of passive- and active-fixation J-shaped leads. PATIENTS AND METHODS: From January 2004 to January 2010, 1,464 patients underwent new pacemaker/implantable cardioverter-defibrillator implantation. Of these, 915 (study population) received a passive- or active-fixation pre-J-shaped lead, or a straight screw-in atrial lead; the remaining 549 patients, who received only a ventricular lead, were excluded. The three study groups were: Group S-FIX (165 patients, 18%), receiving a straight screw-in atrial lead (postshaped in the right appendage); Group J-PASS (690 patients, 75.4%), receiving a passive-fixation J-shaped atrial lead; and Group J-FIX (60 patients, 6.6%), receiving an active-fixation screw-in J-shaped atrial lead. Procedural and short-term complication rates were analyzed up to 3 months postimplantation. RESULTS: One complication occurred in each group (S-FIX 0.6% vs J-PASS 0.1% vs J-FIX 1.6%, P = 0.3, 0.1, and 0.4, respectively, for each comparison). The rate of atrial lead dislodgement was higher in Group J-PASS than in S-FIX but not J-FIX (Group S-FIX 0 vs Group J-PASS 16 vs Group J-FIX 1 dislodgements; P = 0.04 and 0.7, respectively). CONCLUSION: Straight screw-in atrial leads, "J-post shaped" in the right appendage, offer better stability than passive-fixation J-shaped leads and display a similarly acceptable safety profile compared with both the J-shaped systems.

Role of pulmonary veins isolation in persistent atrial fibrillation ablation: the pulmonary vein isolation in persistent atrial fibrillation (PIPA) study.

BACKGROUND: The role of pulmonary veins (PV) isolation in patients with persistent atrial fibrillation (AF) is still debated. The aim of this study was to evaluate the adjunctive role of PV isolation in patients with persistent AF who underwent circumferential PV ablation (anatomical approach). METHODS: We treated 97 consecutive patients presenting with drug-refractory persistent AF by an anatomical approach (group A, n = 36, mean age = 60 +/- 8 years, 29 males) or an integrated approach (group B, n = 61, mean age 59 +/- 10 years, 48 males). In all patients, radiofrequency (RF) ablation was performed by means of a nonfluoroscopic navigation system, in order to anatomically create circumferential lines around the PV. In group B, the persistence of PV potentials was ascertained with a multipolar circular catheter. If PV potentials persisted, RF energy targeting the electrophysiological breakthroughs was delivered to disconnect the PV. Past a 2-month period of observation, success was defined as absence of any atrial tachyarrhythmia recurrence lasting >30 seconds. RESULTS: Total procedure duration (220 +/- 62 minutes vs 140 +/- 43 minutes, P < 0.001), fluoroscopy time (35 +/- 15 minutes vs 17 +/- 9 minutes, P < 0.001), and RF delivery time (48 +/- 22 minutes vs 27 +/- 9 minutes, P < 0.001) were significantly longer in group B than in group A. One cardiac perforation occurred in group A. After 15 +/- 9.1 months, 21 patients in group A (58%) and 34 patients in group B (56%) were free of atrial tachyarrhythmia recurrence (P = 0.9). CONCLUSIONS: In patients with persistent AF, who underwent an anatomical approach, electrophysiological confirmation of PV disconnection significantly increased the fluoroscopy and procedural times, without effect on the long-term outcomes.

Integration of three-dimensional left atrial magnetic resonance images into a real-time electroanatomic mapping system: validation of a registration method.

BACKGROUND: The alignment of three-dimensional (3D) left atrial images acquired by magnetic resonance (MR) with the anatomical information yielded by 3D mapping systems is one of the most critical issues in image integration techniques for catheter ablation of atrial fibrillation (AF). We assessed the accuracy of a simplified method of superimposing 3D MR left atrial images on real-time left atrial electroanatomic maps (registration). METHODS: MR data on the left atrium in 40 patients with drug-refractory AF were imported into the CartoMerge (Biosense Webster, Inc., Diamond Bar, CA, USA) electroanatomic mapping system. Registration was obtained by combining "visual alignment" of one endocardial point and "surface registration" of a limited number of points sampled on the posterior wall of the left atrium. The accuracy of the registration process was assessed through a statistical algorithm incorporated into the CartoMerge system, and through the percentage of pulmonary veins (PVs) in which electrical isolation was achieved after anatomical ablation. RESULTS: The mean registration surface-to-point distance and ablation surface-to-point distance were 1.33 +/- 0.96 mm and 1.47 +/- 1.15 mm, respectively. Upon completion of the circumferential anatomical ablation around the PVs, electrical PV isolation was confirmed by a multipolar circular mapping catheter in 129 of 146 PVs (89%). CONCLUSIONS: Our registration method, which is mainly based on the surface registration of the posterior wall of the left atrium, enables almost 90% of PVs to be isolated by means of an anatomically based catheter ablation approach.

Pulmonary vein isolation predicts freedom from arrhythmia after circumferential antral ablation for paroxysmal atrial fibrillation.

OBJECTIVES: The aims of this observational study were to evaluate (i) the feasibility of obtaining bidirectional pulmonary vein (PV) isolation by means of circumferential radiofrequency ablation of the antral aspect of the PV ostium; (ii) whether the electrophysiological demonstration of bidirectional PV isolation predicts freedom from atrial tachyarrhythmia recurrence after ablation in patients with paroxysmal atrial fibrillation. METHODS: The study group comprised 28 patients affected by frequent recurrences of paroxysmal atrial fibrillation refractory to antiarrhythmic drugs, who underwent transcatheter ablation of the PVs by means of a non-fluoroscopic navigation system. Radiofrequency pulses were delivered in a point-by-point fashion at the antral aspect of the ostium of each vein presenting distal PV potentials. After ablation of each PV, bidirectional isolation was tested by means of a basket catheter. No antiarrhythmic drugs were prescribed on discharge. Outpatient visits, 24-h electrocardiographic Holter monitoring, and continuous 7-day digital electrocardiogram were scheduled at 3, 6, and 12 months. RESULTS: A distal potential was detected in 101/123 (82%) mapped PVs. Bidirectional isolation was obtained in 81/101 (80%) PVs; bidirectional isolation of all targeted PVs was obtained in 17 (61%) patients. After a mean follow-up of 12.2 +/- 4.2 months, clinical success was observed in 15 (53%) patients. On multivariate analysis, only bidirectional isolation of all targeted PVs predicted the clinical success of ablation (P < 0.003; hazard ratio 7.504; confidence interval 1.943-28.990). CONCLUSIONS: Circumferential antral ablation achieves bidirectional isolation in 80% of PVs. Bidirectional isolation of all PVs is essential to curing patients with paroxysmal atrial fibrillation.

Atrio-ventricular block during left atrial flutter ablation.

We present a case of a patient treated with catheter ablation for atrial fibrillation aiming to pulmonary veins isolation. During ablation, atrial fibrillation organized into a left atrial flutter. Electroanatomic and electrophysiologic mapping revealed the anterior left atrium area between the mitral annulus and left atrium septum as a critical region for flutter ablation. After a few pulses of radiofrequency, complete atrio-ventricular block appeared. Finally, we propose pace mapping of the mitral annulus to detect left dislodgment of the compact atrio-ventricular node.

Long-term outcome of patients with atrioventricular node reentrant tachycardia.

BACKGROUND: Little information is available on the natural history of patients with AVNRT. The purpose of this study was to compare the outcome of patients with Atrioventricular node reentrant tachycardia (AVNRT) who underwent ablation with those on antiarrhythmic therapy and those not receiving drugs. METHODS: 93 consecutive patients (mean age=33.5+/-18.1 years) with AVNRT referred to our institution from 1988 to 1993 were prospectively followed-up for a mean of 13.2+/-2.0 years (range=11.4-16.1 years). RESULTS: 18 patients underwent ablation (group 1), 24 received antiarrhythmic therapy (group 2), 38 received no drugs or remained on drug therapy for only few months (group 3), 3 died and 10 were lost to follow-up. The frequency of symptoms at the baseline was higher in group 1 than in groups 2 and 3 (7.8+/-3.7, 3.5+/-2.3, 2.3+/-1.9 episodes/month, respectively; p<0.02 in group 1 vs. group 3). At the end of the follow-up 18/18 (100%) of group 1, 14/23 (61%) of group 2 and 17/38 of group 3 (44.7%) reported being asymptomatic for the previous 3 years. Group 3 patients who became asymptomatic had a shorter duration of symptoms before enrolment (3.7+/-1.5 vs. 7.1+/-3.6 years, p<0.05) and a shorter mean length of the tachycardia episodes (3.8+/-2.4 vs. 42.6+/-17.8 min, p<0.02) than patients from the same group who remained symptomatic. CONCLUSIONS: The main result of this study is that during a long-term follow-up a considerable number of untreated patients with AVNRT become asymptomatic. This finding should be considered for choosing treatment modality and for calculating healthcare costs of ablation vs. medical therapy.

Long-term outcome of right and left atrial radiofrequency ablation in patients with persistent atrial fibrillation.

OBJECTIVES: To investigate the clinical outcome of right and left atrial radiofrequency ablation after the first 12 months in patients with drug-refractory persistent atrial fibrillation (AF), and to identify predictors of long-term success. METHODS: We analyzed the clinical outcome of 74 consecutive patients with a follow-up >12 months who underwent right and left atrial ablation for persistent AF. Patients who did not present symptomatic or asymptomatic atrial tachyarrhythmias (AT) lasting >30 seconds after the first 3 months of follow-up were defined responders to pulmonary veins ablation. RESULTS: After a mean follow-up of 20.2 +/- 6.3 months (12-36), 52/74 (70%) patients were deemed responders. AT relapsed within the first 12 months in 19/74 (26%) patients (17 AF and 2 left atrial flutter). Among those patients who did not relapse within the first 12 months, only 3 patients (5%) presented AF after the first year of follow-up. At the multivariate analysis presence of early AT relapse and history of AF >7 years inversely correlated with a successful long-term clinical outcome. CONCLUSION: Right and left atrial ablation, alone or in association with antiarrhythmic drugs, prevented AT relapses in 70% of patients with drug-refractory persistent AF also after the first 12 months. Presence of AT relapse within the first 3 months and history of AF >7 years identified patients with a lower probability of successful long-term clinical outcome.

Antibiotic prophylaxis with a single dose of cefazolin during pacemaker implantation: incidence of long-term infective complications.

OBJECTIVE: Systemic and localized infections related to permanent pacemaker implantation are not common, but are serious and potentially life-threatening complications. The aims of this prospective observational study were: (1) to assess the safety and long-term efficacy of a simplified scheme of antibiotic prophylaxis, and (2) to identify the predictors of long-term infective complications, in patients undergoing pacemaker implantation or replacement. METHODS AND RESULTS: From October 1998 to July 2001, 852 patients (mean age 77.0 +/- 9.2 years; 474 men) who underwent new permanent pacemaker implantation (69.6%) or pulse generator replacement (30.4%) received a mini-bag of 2 g of cefazolin diluted in 50 mL of saline solution, administered intravenously in 20 minutes before the beginning of the procedure. Early (within 2 months of implantation) and late major and minor infective complications were recorded. During the earlier phase, minor complications were observed in 9 patients (1%). During the long-term phase of the surveillance (mean 25.6 +/- 11.0 months, range 12-55 months) major infective complications were observed in 6 patients (0.7%). On multivariate analysis, no clinical or procedural variable predicted the occurrence of long-term infective complications. CONCLUSIONS: Our data indicate the safety and efficacy of a single, intravenous 2 g dose of cefazolin in preventing infective complications related to pacemaker implantation or replacement. No clinical or procedural variable predicted the occurrence of long-term infective complications.

[Circumferential isolation of pulmonary veins with transcatheter radiofrequency ablation in the treatment of atrial fibrillation]. / Isolamento circonferenziale delle vene polmonari mediante ablazione transcatetere con radiofrequenza per il trattamento della fibrillazione atriale.

BACKGROUND: Circumferential anatomical isolation of the pulmonary veins by radiofrequency transcatheter ablation is a new technique for the treatment of atrial fibrillation (AF). The aim of our study was to evaluate the efficacy and the safety of circumferential radiofrequency ablation of the pulmonary veins and to analyze clinical, echocardiographic and procedural parameters as possible predictors of clinical success. METHODS: We performed circumferential isolation of the pulmonary veins in 33 patients with paroxysmal (15 patients) or persistent AF (18 patients) refractory to at least two antiarrhythmic drugs. All patients continued antiarrhythmic therapy after the procedure for at least 12 months. RESULTS: At the end of the follow-up (mean 13.7 +/- 5.1 months) 70% of the patients resulted responders to the ablation, with no differences between patients with paroxysmal and persistent AF. Complications were observed in 3% of patients. Among clinical, echocardiographic and procedural parameters analyzed none turned out to be predictor of clinical success. CONCLUSIONS: Circumferential isolation of the pulmonary veins by radiofrequency transcatheter ablation associated with antiarrhythmic drugs was efficacious in 70% of patients with either paroxysmal or persistent AF. None of the analyzed variables predicted clinical success.

Variables correlated with early relapses after external electrical cardioversion of persistent atrial fibrillation.

BACKGROUND: The aim of this study was to identify the clinical and echocardiographic variables possibly correlated with the early relapses of atrial fibrillation (AF) after external electrical cardioversion (EC) in a large cohort of patients with persistent AF. METHODS: Two hundred patients (117 males, 83 females, mean age 67.9 +/- 8.7 years) with successful EC of persistent AF (> 72 hours) were included in the present study. In order to identify the predictors of early relapses (within 7 days) of AF, 16 clinical and echocardiographic variables were compared at univariate analysis. The variables with a p value < 0.10 at univariate analysis were subsequently analyzed at multivariate analysis. RESULTS: Seventy-five patients (37.5%) had relapses of AF within 7 days of EC. By univariate analysis only a younger age (65.9 +/- 8.9 vs 69.0 +/- 8.3 years, p = 0.01) was found to be significantly correlated with a higher incidence of early relapses of AF. At multivariate analysis no variable was found to be significantly correlated with early relapses of AF. CONCLUSIONS: In patients with persistent AF, recurrences of this arrhythmia within 7 days of EC occur frequently (37.5%). Multivariate analysis did not reveal any clinical or echocardiographic variable significantly correlated with the early recurrence of AF.

Feasibility of pulmonary vein ostia radiofrequency ablation in patients with atrial fibrillation: a multicenter study (CACAF pilot study).

Radiofrequency (RF) catheter ablation has been proposed as a treatment of atrial fibrillation (AF). Several approaches have been reported and success rates have been dependent on procedural volume and operator's experience. This is the first report of a multicenter study of RF ablation of AF. We treated 44 men and 25 women with paroxysmal (n = 40) or persistent (n = 29), drug refractory AF. Circular pulmonary vein (PV) ostial lesions were deployed transseptally, during sinus rhythm (n = 42) or AF (n = 26), under three-dimensional electroanatomic guidance. Cavo-tricuspid isthmus ablation was performed in 27 (40%) patients. The mean procedure time was 215 +/- 76 minutes (93-530), mean fluoroscopic exposure 32 +/- 14 minutes (12-79), and mean number of RF pulses per patient 56 +/- 29 (18-166). The mean numbers of separate PV ostia mapped and isolated per patient were 3.9 +/- 0.5, and 3.8 +/- 0.7, respectively. Major complications were observed in 3 (4%) patients, including pericardial effusion, transient ischemic attack, and tamponade. At 1-month follow-up, 21 of 68 (31%) patients had had AF recurrences, of whom 8 required electrical cardioversion. After the first month, over a mean period of 9 +/- 3 (5-14) months, 57 (84%) patients remained free of atrial arrhythmias. RF ablation of AF by circumferential PV ostial ablation is feasible with a high short-term success rate. While the procedure and fluoroscopic exposure duration were short, the incidence of major cardiac complications was not negligible.

Effects of verapamil and metoprolol on recovery from atrial electrical remodeling after cardioversion of long-lasting atrial fibrillation.

The aim of this prospective, randomized study was to investigate the effect of pretreatment with two different intracellular calcium-lowering drugs (verapamil and metoprolol) on recovery from atrial effective refractory period (AERP) shortening after internal electrical cardioversion (EC) of persistent atrial fibrillation (AF) in patients on amiodarone. Twenty-one patients on amiodarone for at least 30 days were referred to our hospital for internal EC of a persistent AF refractory to external EC. They were randomized to receive only amiodarone (group AMI, n=7), or amiodarone and verapamil 240 mg/day (group VER, n=7), or amiodarone and metoprolol 100 mg/day (group MET, n=7). Left AERP was measured 10 min and 24 h after EC. AERP was also determined in 13 controls. The AERP after 10 min was significantly shorter in group AMI (201 (31) ms, P<0.02) and group MET (203 (34) ms, P<0.03) than in controls (249 (45) ms), but not in group VER (237 (51) ms, P=NS). The AERP after 24 h was still significantly shorter in group AMI (204 (38) ms, P<0.04) than in controls, but not in group MET (225 (52) ms, P=NS) or in group VER (290 (36) ms, P=NS). Pretreatment with amiodarone and verapamil prevents AERP shortening, while pretreatment with amiodarone and metoprolol only accelerated AERP recovery.

Myocardial perfusion and metabolic changes induced by conventional right and biventricular pacing in dilated cardiomyopathy evaluated by positron emission tomography.

BACKGROUND: Biventricular pacing induces well-known effects on myocardial wall function, apparently providing better results in comparison with conventional right pacing in patients presenting with dilated cardiomyopathy (DCM). However, at the moment the secondary changes in myocardial metabolism induced by pacing devices are unclear. The aim of our study was to evaluate the possible changes in myocardial metabolism and perfusion induced by cardiac pacing in these patients. METHODS: Twenty-eight patients presenting with DCM were submitted to positron emission tomography. Eighteen patients were examined during cardiac pacing, 6 had dual chamber pacemakers implanted for conventional reasons (group A), 12 biventricular pacemakers (group B) for resynchronization purposes; the other 10 patients were considered as controls. Myocardial metabolism was evaluated using 18F-fluorodeoxyglucose (FDG), by the glucose load-insulin technique and perfusion using 13N-ammonia (NH3), injected at rest. A visual and a semiquantitative analysis were performed, calculating on the basis of the regions of interest the septum to lateral uptake (S/L) ratio. RESULTS: In all the 6 patients of group A, a selective defect in FDG uptake was observed in the septum (mean S/L ratio 0.67 +/- 0.15, p < 0.01 with respect to controls), while both the patients in group B and the controls presented a homogeneous distribution of FDG uptake in the myocardial wall (mean S/L ratio 1.01 +/- 0.10 and 0.95 +/- 0.13 respectively, p = NS). On the contrary, at the NH3 positron emission tomography studies no significant difference in myocardial perfusion was found in the three groups of patients, both at the visual and at the semiquantitative analysis (mean S/L ratio group A 1.01 +/- 0.21, group B 0.99 +/- 0.17, controls 0.94 +/- 0.11, p = NS). CONCLUSIONS: Our experience could suggest that, in patients with DCM, conventional right pacing could induce interference in the metabolism of the septum not correlated with perfusion changes. On the other hand, biventricular pacing improves myocardial wall function without interfering with myocardial metabolism and perfusion.