Daily Exposure to Air Pollution Particulate Matter Is Associated with Atrial Fibrillation in High-Risk Patients.

Several epidemiological studies found an association between acute exposure to fine particulate matter of less than 2.5 µm and 10 µm in aerodynamic diameter (PM2.5 and PM10) and cardiovascular diseases, ventricular fibrillation incidence and mortality. The effects of pollution on atrial fibrillation (AF) beyond the first several hours of exposure remain controversial. A total of 145 patients with implantable cardioverter-defibrillators (ICDs), cardiac resynchronization therapy defibrillators (ICD-CRT), or pacemakers were enrolled in this multicentric prospective study. Daily levels of PM2.5 and PM10 were collected from monitoring stations within 20 km of the patient's residence. A Firth Logistic Regression model was used to evaluate the association between AF and daily exposure to PM2.5 and PM10. Exposure levels to PM2.5 and PM10 were moderate, being above the World Health Organization (WHO) PM2.5 and PM10 thresholds of 25 µg/m3 and 50 µg/m3, respectively, on 26% and 18% of the follow-up days. An association was found between daily levels of PM2.5 and PM10 and AF (95% confidence intervals (CIs) of 1.34-2.40 and 1.44-4.28, respectively) for an increase of 50 µg/m3 above the WHO threshold. Daily exposure to moderate PM2.5 and PM10 levels is associated with AF in patients who are not prone to AF.

Association between air pollution and ventricular arrhythmias in high-risk patients (ARIA study): a multicentre longitudinal study.

BACKGROUND: Although the effects of air pollution on mortality have been clearly shown in many epidemiological and observational studies, the pro-arrhythmic effects remain unknown. We aimed to assess the short-term effects of air pollution on ventricular arrhythmias in a population of high-risk patients with implantable cardioverter-defibrillators (ICDs) or cardiac resynchronisation therapy defibrillators (ICD-CRT). METHODS: In this prospective multicentre study, we assessed 281 patients (median age 71 years) across nine centres in the Veneto region of Italy. Episodes of ventricular tachycardia and ventricular fibrillation that were recorded by the diagnostic device were considered in this analysis. Concentrations of particulate matter of less than 10 µm (PM10) and less than 2·5 µm (PM2·5) in aerodynamic diameter, carbon monoxide, nitrogen dioxide, sulphur dioxide, and ozone were obtained daily from monitoring stations, and the 24 h median value was considered. Each patient was associated with exposure data from the monitoring station that was closest to their residence. Patients were followed up for 1 year and then scheduled to have a closing visit, within 1 more year. This study is registered with ClinicalTrials.gov, number NCT01723761. FINDINGS: Participants were enrolled from April 1, 2011, to Sept 30, 2012, and follow-ups (completed on April 5, 2014) ranged from 637 to 1177 days (median 652 days). The incidence of episodes of ventricular tachycardia and ventricular fibrillation correlated significantly with PM2·5 (p<0·0001) but not PM10. An analysis of ventricular fibrillation episodes alone showed a significant increase in risk of higher PM2·5 (p=0·002) and PM10 values (p=0·0057). None of the gaseous pollutants were significantly linked to the occurrence of ventricular tachycardia or ventricular fibrillation. In a subgroup analysis of patients with or without a previous myocardial infarction, only the first showed a significant association between particulate matter and episodes of ventricular tachycardia or ventricular fibrillation. INTERPRETATION: Particulate matter has acute pro-arrhythmic effects in a population of high-risk patients, which increase on exposure to fine particles and in patients who have experienced a previous myocardial infarction. The time sequence of the arrhythmic events suggests there is an underlying neurally mediated mechanism. From a clinical point of view, the results of our study should encourage physicians to also consider environmental risk when addressing the prevention of arrhythmic events, particularly in patients with coronary heart disease, advising them to avoid exposure to high levels of fine particulate matter. FUNDING: There was no funding source for this study.

Ventricular antitachycardia pacing therapy in patients with heart failure implanted with a cardiac resynchronization therapy defibrillator device: Efficacy, safety, and impact on mortality.

BACKGROUND: Cardiac resynchronization therapy defibrillator can terminate ventricular tachycardia (VT) and fast VT (FVT) via antitachycardia pacing (ATP). OBJECTIVES: We evaluated efficacy and safety of ATP, whether ATP induces ventricular arrhythmias after inappropriate ATP or atrial fibrillation (AF) after appropriate ATP, and whether ATP is associated with mortality. METHODS: A total of 1404 patients with a cardiac resynchronization therapy defibrillator were followed in a prospective multicenter observational research. All-cause mortality rates were estimated in patient subgroups in order to uncouple the trigger (VT/FVT or other rhythms causing inappropriate detections) from ATP therapy. RESULTS: Over a median follow-up of 31 months, 2938 VT/FVT episodes were treated with ATP in 360 patients. The adjusted ATP success rate was 63% (95% confidence interval [CI] 57%-69%) on FVTs and 68% (95% CI 62%-74%) on VTs. Acceleration occurred in 55 (1.87%) and syncope in 4 (0.14%) of all ATP-treated episodes. In 14 true VT/FVT episodes in 5 patients, AF followed ATP therapy. In 4 episodes in 2 patients, VT followed ATP inappropriately applied during AF. Death rate per 100 patient-years was 5.6 (95% CI 4.3-7.5) in patients with appropriate ATP and 1.5 (95% CI 0.4-6.1) in patients with inappropriate ATP (P = .045). CONCLUSION: ATP was effective in terminating VT/FVT episodes and displayed a good safety profile. ATP therapies by themselves did not increase death risk; prognosis was indeed better in patients without arrhythmic episodes, even if they received inappropriate ATP, than in patients with ATP on VT/FVT episodes. Adverse outcomes observed in patients receiving implantable cardioverter-defibrillator therapies are probably related to the arrhythmia itself, a marker of disease progression, rather than to adverse effects of ATP.

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.

Prevention of syncope through permanent cardiac pacing in patients with bifascicular block and syncope of unexplained origin: the PRESS study.

BACKGROUND: Syncope in patients with bifascicular block (BFB) is a common event whose causes might be difficult to assess. METHODS AND RESULTS: Prevention of syncope through permanent cardiac pacing in patients with bifascicular block (PRESS) is a multicenter, prospective, randomized, single-blinded study designed to demonstrate a reduction in symptomatic events in patients with bifascicular block and syncope of undetermined origin implanted with permanent pacemaker. Device programming mode (NASPE/BPEG code) at DDD with a lower rate of 60 ppm is compared with backup pacing at DDI with a lower rate of 30 ppm. The end point consisted of (1) syncope, (2) symptomatic presyncopal episodes associated with a device intervention (ventricular pacing), and (3) symptomatic episodes associated with intermittent or permanent atrioventricular block (any degree). One hundred one patients were enrolled and randomized. Primary end point events at 2 years were observed in 23 patients, with a significant lower incidence in the study group (hazard ratio, 0.32; 95% confidence interval [CI], 0.10-0.96; P=0.042). Reduction of any symptoms, associated or not with device intervention, was superior in DDD60 compared with DDI30 (hazard ratio, 0.4; 95% confidence interval, 0.25-0.78; P=0.0053). Fourteen patients developed other rhythm diseases and met class I indication for pacing. The annual incidence of rhythm disease development was 7.4%. CONCLUSIONS: In patients with bifascicular block and syncope of undetermined origin, the use of a dual chamber pacemaker programmed to DDD60 led to a significant reduction of syncope or symptomatic events associated with a cardioinhibitory origin, compared with DDI30 programming. Symptoms associated with a new onset of rhythm disease were found in 15% of the population at 2 years.

In-hospital follow-up of implantable cardioverter defibrillator and pacemaker carriers: patients' inconvenience and points of view. A four-hospital Italian survey.

AIMS: The increasing volume of pacemaker (PM) and implantable cardioverter defibrillator (ICD) implants and problems related to their functioning have highlighted the issue of device follow-ups. Patients' convenience regarding device visits has been little investigated. This work aims at surveying patients' efforts in attending the in-office PM/ICD follow-ups and at evaluating their expectations. METHODS AND RESULTS: In four Italian referral centres, over a 3-month period, a 20-point questionnaire was completed by all consecutive patients at in-hospital PM/ICD visits. In total, 1109 questionnaire/patients were evaluated. Pacemakers were 68%, ICDs 16%, and cardiac resynchronizations (CRTs) (PM + ICD) 16%; 38% were females; mean age was 75 ± 11 years. Almost all were scheduled visits. There was frequent reprogramming and clinical examination, even after 6 months from implant. Perceived inconvenience for the in-office follow-up was relevant in 35% of cases; attitudes towards remote monitoring were positive in 88% of cases. Inter-group analysis showed some significant difference: PM patients were older and more frequently female; ICD carriers were younger, had the highest rate of clinical evaluation, a longer journey time, and the most positive opinion about remote follow-up. Cardiac resynchronization patients had a longer waiting time and the lowest inconvenience. Overall inconvenience was independently predicted by increasing age, lengthy travelling times, and being accompanied; favourable opinions about remote monitoring were predicted by overall inconvenience, and, in ICD carriers only, by lack of clinical examination. CONCLUSIONS: Patients' perceptions of in-hospital PM/ICD visits were affected by age and by journey modalities. Individual factors seem to affect both opinions about in-office visits and expectations towards a possible remote follow-up.

Management of alert messages in the remote monitoring of implantable cardioverter defibrillators and pacemakers: an Italian single-region study.

AIMS: The remote monitoring of pacemakers and implantable cardioverter defibrillators (ICDs) promotes accurate supervision of the patient and device. Alert settings appear to be a crucial parameter of its efficacy. The purpose of our study was to evaluate various settings for alerts and alert message management in patients with pacemakers and ICDs. METHODS AND RESULTS: We prospectively evaluated 282 patients (181 males, 101 females, mean age 72 ± 11 years) who were referred to nine electrophysiological centres in the Veneto region of Italy for a pacemaker (76 patients) or ICD (206 patients) implant in which remote monitoring was activated (Biotronik Home Monitoring®, Biotronik, Berlin, Germany). During a mean follow-up of 382 ± 261 days, we received 106,039 transmissions. In the pacemaker group, the alerts that were most frequently activated were those concerning battery exhaustion, surveying impedances, sensing and threshold measurements, as well as missing transmissions. In the ICD/ICD-cardiac resynchronization therapy group, the alerts nearly always activated were those concerning a detection setoff, battery exhaustion, critical values of impedance, or ineffective maximum energy shock. In both groups, the alarms for heart rate monitoring and supraventricular arrhythmia were activated in fewer cases at higher variability among centres. CONCLUSIONS: Our study demonstrates that more attention is paid to critical technical data than to patients' clinical profiles, probably to limit an excessive flow of data into the centre. Accurate alert settings, personalized to the patients' features, are essential for easier and more effective management of patients who are followed remotely.

Multidimensional gas chromatographic determination of naphthenes, paraffins, olefins, and aromatics in reformed gasolines.

Increasing demand for gasoline, changing regulations concerning the reduction of environmental impact, and new refining technologies have led to the refinement of its composition. Nowadays, gasoline is a complex mixture of different fractions deriving from processes of reforming, cracking, isomerization, and alkylation, with the addition of both oxygenated compounds and butanes. There are regulations governing the mixing of various fractions and it is necessary to analyse the composition of these fractions to ensure that the final composition of commercial gasoline satisfies the required specifications. Moreover, analysis of the composition of each fraction enables the technological process of the fraction examined to be modified as appropriate. In this work some reformed gasolines were analysed by multidimensional gas chromatography. This technique allows good separation of the hydrocarbon types in a single analysis and gives the carbon number distribution within each hydrocarbon type.

Multidimensional gas chromatographic determination of paraffins, olefins and aromatics in naphthas.

In order to cope with the increasing demand for gasoline and the need to reduce environmental impact for sustainable development, refineries have installed refining technology by introducing cracking, reforming, isomerization and alkylation. The standard EN 228: 2004 outlines the specification that gasoline, deriving from the blend of several fractions, must have for use in modem piston engines. Naphtha is one of the products from distilling crude oil that can be used as starting material in the reforming process whose derivatives, which are a fraction of gasoline, depend on the composition of the naphtha. Knowledge of the naphtha composition thus enables to provide the final composition of the products of reforming, the efficiency of the plant and also provides information about the crude oil used. In this paper some naphtha samples were analysed by multidimensional gas chromatography. This technique allows in a single analysis a good separation of the hydrocarbon types and within each hydrocarbon type a good carbon number separation.

Atrial fibrillation in patients with a dual defibrillator: characteristics of spontaneous and induced episodes and effect of ventricular tachyarrhythmia induction.

BACKGROUND: The pattern of FF intervals during atrial fibrillation (AF) has been analyzed in induced and spontaneous AF episodes, after the induction of ventricular fibrillation (VF) and after atrial shock, in order to suggest practical considerations for AF management in patients implanted with antitachycardia devices. METHODS: In 13 patients implanted with a dual-chamber defibrillator, FF intervals were analyzed during two separate induced AF episodes, before and after VF induction over AF, as well as during spontaneous AF episodes and after unsuccessful atrial shocks. The following parameters were considered: mean atrial cycle length (CL), atrial CL stability, and standard deviation of the atrial cycle. RESULTS: The AF pattern had comparable characteristics considering two separate inductions of AF, as well as spontaneous AF episodes. Ventricular tachyarrhythmia induction resulted in a shortening of atrial CL (P < 0.02) and in a less organized AF pattern (P < 0.005). Changes in the FF interval after ineffective shock therapy showed a shortening of AF cycles after shocks with energies far below the defibrillation threshold. CONCLUSIONS: (a) The AF pattern is reproducible in separate inductions of sustained AF and in spontaneous episodes, (b) dynamic changes involving a shortening of the AF cycle and an evolution to a less homogeneous pattern occur after VF induction, revealing a complex interplay between AF and VF, and (c) FF interval analysis after ineffective shock delivery may allow the relationship between delivered shock energy and effective defibrillation energy to be estimated, thereby providing practical suggestions for step-up protocols in atrial cardioversion.

Rate-responsive pacing regulated by cardiac haemodynamics.

AIMS: Trans-valvular impedance (TVI) recording has been proposed for the assessment of cardiac haemodynamics, assuming an inverse relationship between TVI and ventricular volume. We checked whether the TVI sensor can drive the rate-responsive function of a cardiac pacemaker following changes in the inotropic regulation of the heart. METHODS: An external DDD-R pacemaker (Ext Sophos by Medico, Padova, Italy) equipped with the TVI detecting system was tested in 30 patients on the implantation of conventional pacing leads for dual-chamber pacing. Pacing rate regulation was based on the relationship between the stroke volume and the end-diastolic volume, inferred from TVI data. After sensor calibration in basal conditions, beta-adrenergic stimulation was induced by i.v. administration of 2 microg/ml/min isoprenaline (isoproterenol) (IPN). The actual cardiac rate, the TVI waveform, the end-diastolic and systolic TVI in each cardiac cycle and the TVI-indicated rate were stored in memory as a function of time and down-loaded at the end of the session. RESULTS: All patients with intrinsic atrial activity (28/30) showed a positive chronotropic response to IPN, coupled with a significant increase in end-diastolic TVI and a four-times larger increase in end-systolic TVI. The TVI inotropic index mirrored the sinus rate time-course, with a linear correlation between the two parameters (r(2)>0.7 in 25/28 cases). As a result, the TVI-indicated rate closely reproduced the sinus rate. CONCLUSIONS: The study confirms the reliability of the haemodynamic information derived from TVI and supports its application in the regulation of rate-responsive pacing.

Implantable dual-chamber defibrillator for the selective treatment of spontaneous atrial and ventricular arrhythmias: arrhythmia incidence and device performance.

INTRODUCTION: Atrial tachyarrhythmias are a common co-morbidity in patients with an ICD indication. Recently introduced ICD's are equipped to independently detect and treat atrial and ventricular tachyarrhythmias. The purpose of this prospective study was to evaluate the incidence and termination of spontaneous atrial and ventricular tachyarrythmias in patients with a history of atrial tachyarrhythmias. METHODS AND RESULTS: Ninety patients, 70% male with an ICD indication and history of atrial tachyarrhythmia (LVEF 45 +/- 6%, [AT/AF indication 55 +/- 10, AT/VT 45 +/- 16], 46% CAD) were enrolled and 89 were implanted with a VENTAK PRIZM AVT (Guidant). Spontaneous atrial and ventricular tachyarrhythmias were printed and evaluated during an average follow-up period of 272 +/- 72 days utilizing the stored intracardial electrogram function of the device. Nineteen patients (21%) presented had only atrial tachyarrhythmias, 32 patients (36%) had both atrial and ventricular tachyarrhythmias and 18 patients (20%) had only ventricular tachyarrhythmias. Patients with only atrial tachyarrhythmias had a total of 3274 atrial episodes; 2002 terminated spontaneously, 1264 were treated with ATP and 8 with shock therapy. ATP was successful in 735 (58%) of 1264 episodes. Patients with both atrial and ventricular tachyarrhythmias had 7277 documented atrial tachyarrhythmias, 5231 terminated spontaneously, 1153 of 2009 were terminated by ATP (57.4%) and 37 by shock therapy (20 patient controlled). Atrial tachyarrhythmias identified as atrial flutter (AT) by the atrial rhythm classification (ARC) algorithm had a higher ATP conversion success rate than episodes identified as atrial fibrillation (AF); 66.7% for AT and 26.4% for AF. Patients with only ventricular tachyarrhythmias had 690 documented episodes, 401 terminated spontaneously, 248 (85.8%) were terminated by ATP and 41 by shock. CONCLUSION: Seventy-seven percent of patients with an ICD indication had spontaneous atrial and/or ventricular tachyharrhythmias within the first 6 months after ICD implantation. ATP therapy terminated 58% of all atrial tachyarrhytmias and 66.7% of the atrial flutters. The dual chamber ICD detected, classified and terminated all ventricular tacharrhythmias appropriately.

Hemodynamic effects of atrial septal pacing in cardiac resynchronization therapy patients.

INTRODUCTION: Spontaneous or pacing-induced interatrial conduction delay may affect the outcome of heart failure patients treated with cardiac resynchronization therapy (CRT). The objective of this study was to evaluate the impact of the atrial pacing site (right atrial appendage, RAA; and low interatrial septum, LIS) during biventricular (BV) pacing on the left ventricular (LV) systolic function in candidates for CRT. METHODS AND RESULTS: Fifteen heart failure patients with left bundle branch block and LV ejection fraction < or =35% were enrolled. Electrodes were placed at the RAA, LIS, right ventricular apex, and LV free wall. A DDD protocol was tested, which consisted of 50 beats in AAI mode from the RAA followed by 50 beats in BV DDD mode with atrial pacing at the RAA (DDD_RAA) or at the LIS (DDD_LIS) at four AV delays. The average (+/-SD)%LV+dP/dtmax increase during DDD_RAA and DDD_LIS pacing with respect to baseline was 24 +/- 16% and 21 +/- 15%, respectively (P < 0.01), and average percentage change in aortic pulse pressure during DDD_RAA and DDD_LIS with respect to baseline (%PP) was 13 +/- 8% and 13 +/- 7% (ns). CONCLUSIONS: Our results show a significant hemodynamic improvement with both DDD_RAA and DDD_LIS biventricular pacing compared to AAI pacing. However DDD_LIS pacing was not superior to DDD_RAA pacing in acute hemodynamic responses.

Impact of coronary sinus lead position on biventricular pacing: mortality and echocardiographic evaluation during long-term follow-up.

INTRODUCTION: Biventricular pacing is an established treatment for congestive heart failure. Whether the anatomic location of the coronary sinus (CS) lead affects outcomes is unknown. The aim of this study was to evaluate the clinical response and mortality in patients who had transvenous CS leads placed in different anatomic branches for biventricular pacing. METHODS AND RESULTS: We evaluated 233 consecutive patients with New York Heart Association (NYHA) class III-IV heart failure and ejection fraction <35% who had successful placement of a transvenous left ventricular lead through a CS venous branch. Patients were divided into two groups based on anatomic lead position. Group 1 (n = 66) included leads in the anterior and anterolateral branches. Group 2 (n = 167) included leads in the lateral and posterolateral branches. Postimplant, functional capacity improved from an average 3.1 to 2.7 in group 1 (P = 0.001) and from 3.1 to 2.3 in group 2 (P = 0.001). Left ventricular ejection fraction (LVEF) measured by transthoracic echocardiography did not improve significantly in group 1 (pre-LVEF 18%, post-LVEF 20%; P = NS) but increased significantly from 19% to 27% in group 2 (P = 0.008). Despite the difference in ejection fraction response, the mortality in the two groups after a mean follow-up of 546 days was similar (13.6% group 1 vs 17.9% group 2). CONCLUSION: Placement of the CS lead in the lateral and posterolateral branches is associated with significant improvement in functional capacity and greater improvement in left ventricular function compared with the anterior CS location. This improvement does not appear to influence mortality.

A randomized, double-blind, placebo-controlled study of permanent cardiac pacing for the treatment of recurrent tilt-induced vasovagal syncope. The vasovagal syncope and pacing trial (SYNPACE).

AIMS: Recently, some studies revealed the efficacy of pacemaker implantation in decreasing recurrences in patients with vasovagal syncope. As these studies were not blinded or placebo-controlled, the benefits observed might have been due to a bias in the assessment of outcomes or to a placebo effect of the pacemaker. We performed a randomized, double-blind, placebo-controlled study in order to ascertain if pacing therapy reduces the risk of syncope relapse. METHODS AND RESULTS: Twenty-nine patients (53 +/- 16 years; 19 women) with severe recurrent tilt-induced vasovagal syncope (median 12 syncopes in the lifetime) and 1 syncopal relapse after head-up tilt testing underwent implantation of a pacemaker, and were randomized to pacemaker ON or to pacemaker OFF. During a median of 715 days of follow-up, 8 (50%) patients randomized to pacemaker ON had recurrence of syncope compared to 5 (38%) of patients randomized to pacemaker OFF (p = n.s.); the median time to first syncope was longer in the pacemaker ON than in pacemaker OFF group, although not significantly so (97 [38-144] vs 20 [4-302] days; p = 0.38). There was also no significant difference in the subgroups of patients who had had a mixed response and in those who had had an asystolic response during head-up tilt testing. CONCLUSION: Our data were unable to show a superiority of active pacing versus inactive pacing in preventing syncopal recurrence in patients with severe recurrent tilt-induced vasovagal syncope.

Acute comparative effect of right and left ventricular pacing in patients with permanent atrial fibrillation.

We tested the hypothesis that left ventricular (LV) pacing is superior to right ventricular (RV) apical pacing in patients undergoing atrioventricular (AV) junction ablation and pacing for permanent atrial fibrillation. The potential benefit of LV over RV pacing needs to be evaluated without the confounding effect of other variables that can influence cardiac performance. An acute intrapatient comparison of the QRS width and echocardiographic parameters between RV versus LV pacing was performed within 24 h after ablation in 44 patients. Both modes of pacing were also compared with pre-implantation values. Compared with RV pacing, LV pacing caused a 5.7% increase in the ejection fraction (EF) and a 16.7% decrease in the mitral regurgitation (MR) score; the QRS width was 4.8% shorter with LV pacing. Similar results were observed in patients with or without systolic dysfunction and/or native left bundle branch block, except for a greater improvement in MR in the latter group. Compared with pre-ablation measures, the EF increased by 11.2% and 17.6% with RV and LV pacing, respectively; the MR score decreased by 0% and 16.7%; and the diastolic filling time increased by 12.7% and 15.6%.Rhythm regularization achieved with AV junction ablation improved EF with both RV and LV pacing; LV pacing provided an additional modest but favorable hemodynamic effect, as reflected by a further increase of EF and reduction of MR. The effect seems to be equal in patients with both depressed and preserved systolic functions and in those with and without native left bundle branch block.

Evaluation of a dual chamber implantable cardioverter defibrillator for the treatment of atrial and ventricular arrhythmias.

Eighty-nine patients with a documented history of atrial tachyarrhythmias or fibrillation (AF) received a cardioverter defibrillator designed to selectively differentiate and treat atrial and ventricular arrhythmias. Twenty-two patients received a coronary sinus lead and, therefore, could use a separate shock vector for selective treatment of atrial tachyarrhythmias/AF. The device is designed to treat tachyarrhythmias with antitachycardia pacing (ATP) and/or shock therapy using an atrial and/or a ventricular shock vector. Patients underwent induction and shock termination of atrial or dual tachyarrhythmias (AF/VF) to verify proper device function and to measure the arrhythmia detection time with enhancements and preventive algorithms programmed On and Off, respectively. Detection time for 329 VF inductions was 2.41 +/- 0.64 seconds with enhancements On and 2.29 +/- 0.47 with enhancements Off (NS). At implant or predischarge, 283 AF and/or AF/VF (121 atrial and 162 atrial/ventricular fibrillation) were induced. Shock conversion efficacy was 89.8% with AF conversion energies ranging from 0.9 to 27 J. Thirteen of the 23 patients had atrial shock conversions using the separate shock vector with an average conversion energy of 1.9 +/- 1.4 J. (range 0.5-5 J). During follow-up the efficacy of ATP on atrial tachyarrhythmias was 59% and the efficacy of delivered shocks on AF was 85%. This new dual chamber cardioverter defibrillator appropriately detected and classified atrial arrhythmias, and shock therapy for AF was highly effective. The detection algorithm differentiated atrial tachyarrhythmia/AF and did not delay VF detection. The separate shock vector converted induced AF with energies ranging from 0.6 to 5 J.

Combined use of morphology discrimination, sudden onset, and stability as discriminating algorithms in single chamber cardioverter defibrillators.

Morphology Discrimination (MD) is a rhythm discriminator based on QRS morphology analysis that can be combined with other discriminators like Stability, with or without Sinus Interval History (SIH) and Sudden Onset. Thirty-five patients implanted with a St. Jude Medical single chamber ICD were evaluated during exercise testing, during induced AF, and during follow-up for 14 +/- 5 months. At exercise testing (60 episodes detected) MD had a specificity (SP) of 96.7% and Sudden Onset a SP of 91.7%; during induced AF (25 episodes) both MD and Stability had a SP of 96.0%. The diagnostic performance on spontaneous arrhythmias was as follows: for ventricular tachycardia (126 episodes) a sensitivity (SE) of 94.4% for MD, 92.1% for Sudden Onset, 89.7% for Stability without SIH and 79.4% for Stability + SIH; for sinus tachycardia (44 episodes) a SP of 86.4% for MD, 97.7% for Sudden Onset, 2.3% for Stability and of 95.5% for Stability + SIH. For AF (165 cases) a SP of 67.9% for MD, 69.1% for Stability and 90.3% for Stability + SIH, 44.8% for Sudden Onset. Use of MD alone provided a SE of 94.4% and a SP of 71.4% for spontaneous arrhythmias and combined use of the discriminators in a "2 of 3" diagnostic logic implied a SP of 90.9% with maintenance of 96.0% of SE. In single chamber ICDs a wide range of SE/SP ratios may be obtained by use of multiple discriminators, but use of the algorithm in a 2 of 3 diagnostic logic may achieve a SP of 90.9% and a SE of 96.0%.