Novel ventricular tachyarrhythmia detection enhancement detects undertreated life-threatening arrhythmias.

BACKGROUND: Ventricular tachyarrhythmias (VTA) with low and varying signal amplitudes and morphologies may not be successfully identified utilizing traditional implantable cardioverter-defibrillator algorithms. OBJECTIVE: Develop and validate a novel algorithm (VF Therapy Assurance, VFTA) to improve detection and timely delivery of high-voltage therapy (HVT) for these arrhythmias. METHODS: Arrhythmia detection was simulated on recorded VTA electrograms (EGMs) utilizing Abbott's Merlin.net database. EGMs where an HVT occurred only when VFTA was enabled, or where VFTA provided an HVT >30 seconds earlier than without VFTA, were readjudicated with physician review. As VFTA never prevents detection or therapy, EGMs where VFTA did not activate or alter HVT were not adjudicated. RESULTS: Among 564,353 recorded VTA EGMs from 20,000 devices, VFTA altered HVT in 105 EGMs from 67 devices. Physician adjudication determined that 81.9% (86/105) of these EGMs were true undertreated VTA episodes and would have received appropriate HVT with VFTA enabled. Furthermore, 65% of the episodes (56/86) were ventricular fibrillation, were polymorphic, did not self-terminate during the recording window, or were not amenable antitachycardia pacing. Of those, 87.5% (49/56) would not have elicited HVT without VFTA. Overall, VFTA provided new or earlier appropriate HVT in 0.27% (53/20,000) of devices with an increase in inappropriate HVT in 0.07% (14/20,000) devices. CONCLUSION: The VFTA algorithm successfully identifies VTA missed by traditional detection algorithms, owing to undersensed ventricular signals resulting in the rate falling below the programmed detection rate. The use of VFTA increases the likelihood of delivering life-saving HVT.

Real-world Adoption of Smartphone-based Remote Monitoring Using the Confirm Rx™ Insertable Cardiac Monitor.

While previous generations of insertable cardiac monitors (ICMs) required a bedside monitor for remote monitoring (RM), the Confirm Rx™ ICM (Abbott, Chicago, IL, USA) utilizes Bluetooth®, Wi-Fi/cellular technology, and a smart device to connect to the RM system. We aimed to characterize compliance, connectivity, and event transmission timing with the Confirm Rx™ ICM RM system. The study cohort included American patients who received the Confirm Rx™ ICM with SharpSense™ technology within three months of release (May-July 2019). Compliance with RM was quantified as the proportion of patients registering the patient app on their smart device and transmitting at least once. Connectivity was measured as the median number of days between consecutive transmissions per patient. Event transmission time was measured from episode detection to availability on the Merlin.net™ RM system (Abbott). Time from transmission until review by a clinician was examined. Values for device connectivity, episode transmission timing, and clinician view times were reported as median [first quartile, third quartile]. Of 5,666 patients who received a Confirm Rx™ ICM, 97% registered their patient app and 92% transmitted data at least once. Among those utilizing RM (aged 66 ± 15 years; 49% female), connectivity occurred every 1.5 [1.2, 2.4] days, or 4.7 times per week. Patient-reported symptoms were transmitted to Merlin.net™ within 2.9 [2.1, 3.8] minutes of event onset and viewed by the clinician within 0.9 [0.4, 3.1] days, while device-detected episodes without symptoms were transmitted within 18.5 [11.2, 36.5] hours and then viewed within 0.8 [0.3, 2.5] days. This real-world study demonstrated excellent patient compliance with the smartphone-based RM paradigm enabled by Confirm Rx™, suggesting the suitability of this technology for future cardiac implantable devices.

Multicenter prospective observational long-term follow-up study of endocardial cardiac resynchronization therapy using the Jurdham procedure.

BACKGROUND: Endocardial cardiac resynchronization therapy (eCRT) avoids the limitations and failures of coronary sinus (CS) resynchronization. However, data regarding long-term outcomes are lacking. OBJECTIVE: The purpose of this study was to report the long-term outcome of eCRT performed using the Jurdham procedure in a real-world setting. METHODS: eCRT was performed in patients who failed a CS implant or failed to respond to cardiac resynchronization therapy (CRT), or in selected patients requiring lifelong oral anticoagulation (OAC). Left ventricular ejection fraction (LVEF), New York Heart Association functional class (NYHA FC), and left ventricular stimulation parameters were assessed during long-term follow-up (FU). RESULTS: From August 2009 to March 2018, the Jurdham procedure was performed in 88 patients at 15 centers in 8 countries, with FU of 32.88 ± 61.52 months (range 0-88 months; 196 patient-years). NYHA FC improved from 2.9 preimplant to 1.3 during FU. LVEF increased <10 percentage points from baseline in 7% of patients, between 10 and 20 percentage points in 11% of patients, and >20 percentage points in 82% of patients. All-cause mortality at 60 months was 30.5%. Three transient ischemic attacks (1.53 per 100 patient-years) and 6 strokes (3.06 per 100 patient-years) occurred. Of the 6 patients with stroke, 4 (66%) had almost complete recovery. CONCLUSION: eCRT using the Jurdham procedure is an effective and safe technique in anticoagulated patients. This approach may be an attractive option for patients with failed CS implants or nonresponders to CS CRT. In addition, it might be a reasonable approach as a first option for treatment of patients requiring lifelong OAC.

Increased Hospitalizations and Overall Healthcare Utilization in Patients Receiving Implantable Cardioverter-Defibrillator Shocks Compared With Antitachycardia Pacing.

OBJECTIVES: The purpose of this study was to evaluate the effect of these therapies on healthcare utilization in a large patient cohort. BACKGROUND: Antitachycardia pacing (ATP) terminates ventricular tachycardia and avoids delivery of high-voltage shocks. Few data exist on the impact of shocks on healthcare resource utilization compared with ATP. METHODS: PROVIDE (Programming Implantable Cardioverter Defibrillators in Patients With Primary Prevention Indication) was a prospective study of patients who received an implantable cardioverter-defibrillator (ICD) for primary prevention at 97 U.S. centers (2008 to 2010). We categorized the PROVIDE patients by the type of therapy delivered: no therapy, ATP only, or at least 1 shock. All ICD therapies, hospitalizations, and deaths were adjudicated. Cumulative cardiac hospitalizations, risk of all-cause death or cardiac hospitalization, and annual costs were compared between groups. RESULTS: Of the 1,670 patients in PROVIDE, followed up for 18.1 ± 7.6 months, 1,316 received no therapy, 152 had ATP only, and 202 received at least 1 shock. Patients receiving no therapy and those receiving only ATP had a lower cumulative hospitalization rate and were at lower risk for death or hospitalization (hazard ratio: 0.33 [p < 0.001] and 0.33 [p < 0.002], respectively). The cost of hospitalization was $2,874 per patient-year (95% confidence interval: $877 to $5,140; p = 0.002) higher for those receiving at least 1 shock than for those who received ATP only. There was no difference in outcomes or cost between patients receiving only ATP and those without therapy. CONCLUSIONS: Among patients implanted with an ICD for primary prevention, those who received only ATP therapy had reduced hospitalizations, mortality, and cost compared with those who received at least 1 high-voltage shock and had equivalent outcomes to patients who did not require any therapy. (Programming Implantable Cardioverter Defibrillators in Patients With Primary Prevention Indication [PROVIDE]; NCT00743522).

Additional electrodes on the Quartet™ LV lead provide more programmable pacing options than bipolar and tripolar equivalents.

AIMS: The aim of this study was to evaluate any benefits to the number of viable pacing vectors and maximal spatial coverage with quadripolar left ventricular (LV) leads when compared with tripolar and bipolar equivalents in patients receiving cardiac resynchronization therapy (CRT). METHODS AND RESULTS: A meta-analysis of five previously published clinical trials involving the Quartet™ LV lead (St Jude Medical, St Paul, MN, USA) was performed to evaluate the number of viable pacing vectors defined as capture thresholds ≤2.5 V and no phrenic nerve stimulation and maximal spatial coverage of viable vectors in CRT patients at pre-discharge (n = 370) and first follow-up (n = 355). Bipolar and tripolar lead configurations were modelled by systematic elimination of two and one electrode(s), respectively, from the Quartet lead. The Quartet lead with its four pacing electrodes exhibited the greatest number of pacing vectors per patient when compared with the best bipolar and the best tripolar modelled equivalents. Similarly, the Quartet lead provided the highest spatial coverage in terms of the distance between two furthest viable pacing cathodes when compared with the best bipolar and the best tripolar configurations (P < 0.05). Among the three modelled bipolar configurations, the lead configuration with the two most distal electrodes resulted in the highest number of viable pacing vectors. Among the four modelled tripolar configurations, elimination of the second proximal electrode (M3) resulted in the highest number of viable pacing options per patient. There were no significant differences observed between pre-discharge and first follow-up analyses. CONCLUSION: The Quartet lead with its four electrodes and the capability to pace from four anatomical locations provided the highest number of viable pacing vectors at pre-discharge and first follow-up visits, providing more flexibility in device programming and enabling continuation of CRT in more patients when compared with bipolar and tripolar equivalents.

Performance of an ICD algorithm to detect lead noise and reduce inappropriate shocks.

BACKGROUND: Implantable cardioverter-defibrillators (ICD) provide treatment for life-threatening ventricular tachyarrhythmias. Failure of the pace/sense conductor of an ICD lead can cause noise on the sensing electrogram (EGM) that may be misinterpreted as ventricular activity, triggering inappropriate therapy. An algorithm based upon the confirmation of ventricular activity from a far-field EGM has been developed to reduce inappropriate therapies resulting from this type of lead failure, while ensuring that appropriate therapy is delivered. The objectives of this study were to evaluate the algorithm's ability to discriminate lead noise from ventricular tachycardia/ventricular fibrillation (VT/VF) and to determine whether it inhibits inappropriate shocks without delaying appropriate shocks. METHODS: The algorithm was prospectively tested using near- and far-field EGM recordings from patients in three conditions: normal sinus rhythm with sustained and non-sustained lead noise via manipulation of the ICD pocket or lead system, and VT/VF induced during defibrillation threshold testing. The recordings were played through a bench-top device running the algorithm with the diagnosis, time to diagnosis, and inhibition of therapy documented. RESULTS: The algorithm detected noise and withheld inappropriate therapy in 231 of 238 recordings of sustained lead noise that would otherwise have been diagnosed as VT/VF (97.1%). Non-sustained lead noise was correctly diagnosed in 47 of the 52 recordings (90.4%). The device appropriately identified all 853 recordings of VT/VF (100%), without an increase in the time to detection (0.01 ± 0.14 s). CONCLUSIONS: The SecureSense(TM) algorithm correctly diagnosed sustained and non-sustained lead noise recordings without compromising detection of VT/VF. Use of the algorithm may reduce inappropriate shocks and alert clinicians to lead noise indicative of lead failure.

Reduced Mortality Associated With Quadripolar Compared to Bipolar Left Ventricular Leads in Cardiac Resynchronization Therapy.

OBJECTIVES: The study sought to compare survival, lead deactivation, and lead replacement with quadripolar versus bipolar leads using a retrospective cohort of patients with newly implanted cardiac resynchronization therapy (CRT) systems. BACKGROUND: In CRT, quadripolar left ventricular (LV) leads offer alternative pacing sites and vectors not available with bipolar LV leads, which may improve the effectiveness of the therapy. METHODS: Using nationwide data from device implant registration records of a single manufacturer, we identified patients with a de novo cardiac resynchronization therapy with defibrillation (CRT-D) implanted between November 30, 2011, and May 31, 2013. Patients were followed for up to 24 months. The primary predictor was LV lead type (quadripolar Quartet [St. Jude Medical, St. Paul, Minnesota] LV lead or bipolar LV lead). The primary outcome was death and the secondary outcomes were LV lead replacement and deactivation. RESULTS: Among 23,570 patients (69.5 ± 11.1 years of age; 28% female; median follow-up time 1.14 years), 18,406 had quadripolar and 5,164 had bipolar LV leads. The quadripolar and bipolar groups had 5.04 and 6.45 deaths per 100 patient-years, respectively (p < 0.001). After multivariate adjustment, the quadripolar lead was associated with a lower risk of deactivation (hazard ratio [HR]: 0.62; 95% confidence interval [CI]: 0.46 to 0.84; p = 0.002), replacement (HR: 0.67; 95% CI: 0.55 to 0.83; p < 0.001), and death (HR: 0.77; 95% CI: 0.69 to 0.86; p < 0.001). CONCLUSIONS: In this observational study of CRT-D devices, use of a quadripolar, compared to a bipolar LV lead, was associated with a reduction in LV lead deactivation, replacement, and mortality.

Trends in Use and Adverse Outcomes Associated with Transvenous Lead Removal in the United States.

BACKGROUND: Transvenous lead removal (TLR) has made significant progress with respect to innovation, efficacy, and safety. However, limited data exist regarding trends in use and adverse outcomes outside the centers of considerable experience for TLR. The aim of our study was to examine use patterns, frequency of adverse events, and influence of hospital volume on complications. METHODS AND RESULTS: Using the Nationwide Inpatient Sample, we identified 91 890 TLR procedures. We investigated common complications including pericardial complications (hemopericardium, cardiac tamponade, or pericardiocentesis), pneumothorax, stroke, vascular complications (consisting of hemorrhage/hematoma, incidents requiring surgical repair, and accidental arterial puncture), and in-hospital deaths described with TLR, defining them by the validated International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code. We specifically assessed in-hospital death (2.2%), hemorrhage requiring transfusion (2.6%), vascular complications (2.0%), pericardial complications (1.4%), open heart surgery (0.2%), and postoperative respiratory failure (2.4%). Independent predictors of complications were female sex and device infections. Hospital volume was not independently associated with higher complications. There was a significant rise in overall complication rates over the study period. CONCLUSIONS: The overall complication rate in patients undergoing TLR was higher than previously reported. Female sex and device infections are associated with higher complications. Hospital volume was not associated with higher complication rates. The number of adverse events in the literature likely underestimates the actual number of complications associated with TLR.

What did we learn from Riata™?

The Riata™ 8 French (Fr) and Riata ST™ 7 Fr families of silicone leads have experienced a specific form of insulation abrasion characterized by externalization of conductor cables outside the lead body. Design differences between the 8 Fr and 7 Fr leads make conductor externalization less likely in the smaller diameter lead. The Riata Lead Evaluation Study (RLES) reported on the prevalence of externalized conductors (EC) in patients implanted with Riata™ and Riata ST™ silicone leads and provided details on the incidence of electrical abnormalities in Riata™ and Riata ST™ leads with and without EC. The prevalence of EC was significantly lower for the Riata ST™ leads (7 Fr) as compared with Riata™ leads (8 Fr) (24/259 (9.3 %) vs. 125/517 (24.2 %), P < 0.001), and the majority of leads with EC were not associated with electrical malfunction. The aim of this manuscript is to describe the design of the Riata™ and Riata ST™ families of leads, provide details regarding the mechanisms and rates of lead failure, and discuss recommendations for patient management.

The Relationship Between Level of Adherence to Automatic Wireless Remote Monitoring and Survival in Pacemaker and Defibrillator Patients.

BACKGROUND: Remote monitoring (RM) technology embedded within cardiac rhythm devices permits continuous monitoring, which may result in improved patient outcomes. OBJECTIVES: This study used "big data" to assess whether RM is associated with improved survival and whether this is influenced by the type of cardiac device and/or its degree of use. METHODS: We studied 269,471 consecutive U.S. patients implanted between 2008 and 2011 with pacemakers (PMs), implantable cardioverter-defibrillators (ICDs), or cardiac resynchronization therapy (CRT) with pacing capability (CRT-P)/defibrillation capability (CRT-D) with wireless RM. We analyzed weekly use and all-cause survival for each device type by the percentage of time in RM (%TRM) stratified by age. Socioeconomic influences on %TRM were assessed using 8 census variables from 2012. RESULTS: The group had implanted PMs (n = 115,076; 43%), ICDs (n = 85,014; 32%), CRT-D (n = 61,475; 23%), and CRT-P (n = 7,906; 3%). When considered together, 127,706 patients (47%) used RM, of whom 67,920 (53%) had ≥75%TRM (high %TRM) and 59,786 (47%) <75%TRM (low %TRM); 141,765 (53%) never used RM (RM None). RM use was not affected by age or sex, but demonstrated wide geographic and socioeconomic variability. Survival was better in high %TRM versus RM None (hazard ratio [HR]: 2.10; p < 0.001), in high %TRM versus low %TRM (HR: 1.32; p < 0.001), and also in low %TRM versus RM None (HR: 1.58; p < 0.001). The same relationship was observed when assessed by individual device type. CONCLUSIONS: RM is associated with improved survival, irrespective of device type (including PMs), but demonstrates a graded relationship with the level of adherence. The results support the increased application of RM to improve patient outcomes.

Multicenter experience with extraction of the Riata/Riata ST ICD lead.

BACKGROUND: In November 2011, the Food and Drug Administration issued a class I recall of Riata and Riata ST implantable cardioverter-defibrillator leads. Management recommendations regarding the recall have remained controversial. OBJECTIVE: Data regarding the safety and feasibility of extraction of Riata implantable cardioverter-defibrillator leads are limited. METHODS: We performed a retrospective study of patients undergoing extraction of Riata/Riata ST leads at 11 centers. RESULTS: Between July 2003 and April 2013, 577 Riata/Riata ST leads were extracted from 577 patients (Riata 467, [84%]; Riata ST 89, [16%]). Complete procedural success achieved in 99.1%. The cohort was 78% men, with a mean age of 60 years and a mean left ventricular ejection fraction of 34% ± 14%. The mean implant duration was 44.7 months (range 0-124.6 months). The majority of leads extracted were for infection (305 [53.0%]) and 220 (35.7%) for lead malfunction. Evaluation for lead integrity was performed in 295 cases. Of these, 34.9% were found to have externalized cables. Implant duration was significantly longer in leads with externalized cables (P < .0001). No difference in lead integrity was noted between Riata and Riata ST leads (11.7% vs. 17.7% failure; P = .23). Among leads in which cable externalization was noted, laser sheaths were used more frequently (P = .01). Major complications included 3 superior vena cava/right ventricular perforations requiring surgical intervention with 1 death 12 days after the procedure and 1 pericardial effusion requiring percutaneous drainage (0.87%). CONCLUSION: Extraction of the Riata/Riata ST leads can be challenging, and leads with externalized cables may require specific extraction techniques. Extraction of the Riata/Riata ST leads can be performed safely by experienced operators at high-volume centers with a complication rate comparable to published data.

Shocktivity: ability and avoidance of daily activity behaviors in ICD patients.

BACKGROUND: Implantable cardioverter defibrillator (ICD) shocks terminate potentially life-threatening arrhythmias and may alter patient behavior. Patients are aware of which activities they have the ability to perform, but they may choose to avoid these behaviors after receiving a shock. This study examined ICD patient ability and avoidance of progressively exertive behaviors. METHODS: ICD patients (N = 443) across the United States were surveyed using an online measure including the 12-item Duke Activity Status Index. RESULTS: As expected, many patients reported being unable to participate in more physically exertive activities such as strenuous athletic exertion (68.8%), sex (35.4%), and running a short distance (49.0%). Avoidance rates were also relatively high, as patients who reported being able to participate in these activities also reported avoiding them (ie, strenuous athletics, 76.1%). Similarly, the majority of patients reported ability to engage in sexual activity (64.6%) but many chose to avoid sexual activity (51.0%). Multiple reasons were reported for avoidance, including fear of shock, fear of heart rate increase, doctor instruction, no desire, and an "other" option. CONCLUSION: Many ICD patients experience behavioral limitations because of both a perceived inability and preference to avoid exertive activities, and possibly a prescription to do so, particularly strenuous athletic exertion. Clinical and research attention to ICD patient activity levels and reasons for avoidance may improve daily functioning and help patients return to preimplant levels of activity.

The impact of transvenous lead extraction on tricuspid valve function.

BACKGROUND: Few data exist regarding the effect of transvenous lead extraction (TLE) on tricuspid valve function. The objective of this study was to examine the effect of TLE on the development of postprocedure tricuspid regurgitation (TR). OBJECTIVE: To assess the impact of TLE on tricuspid valve function. METHODS: A single center retrospective analysis of consecutive patients referred for TLE between June 2006 and November 2011. Patients were included only if they underwent transthoracic echocardiography (TTE) before and after lead extraction (N = 124). Patients were assigned a preprocedure and postprocedure TR score on a continuous scale from 0 to 6 (0 = none, 1 = trace, 2 = mild, 3 = mild/moderate, 4 = moderate, 5 = moderate/severe, and 6 = severe). A clinically significant increase in TR was defined as both (1) an increase in TR score of at least two points, and (2) a postprocedure TR score ≥4 (moderate). RESULTS: A total of 124 patients referred for TLE underwent a TTE both before (9 ±16 months) and after lead extraction (4 ± 8 months). A total of 200 leads (1.6 ± 0.8 per patient) were extracted. The mean change in TR score after lead extraction was +0.18 (95% confidence interval [CI] -0.03 to 0.39, P = 0.11). A clinically significant increase in TR occurred in 7/124 (5.6% [CI 2.3-11.3%]) patients. Age ≥75 (+0.45, [CI 0.07-0.84, P = 0.02]), removal of ≥2 leads (+0.40 [CI 0-0.81, P = 0.05]), and powered sheath-assisted extraction (+0.34 [CI 0.05-0.62, P = 0.02]) were significantly associated with an increase in TR score. CONCLUSION: TLE is rarely associated with the development of clinically significant TR. In our cohort, patient age ≥75 years, pacemaker as opposed to ICD, and removal of ≥2 leads predicted worsening TR.

Patients treated with catheter ablation for ventricular tachycardia after an ICD shock have lower long-term rates of death and heart failure hospitalization than do patients treated with medical management only.

BACKGROUND: Ventricular arrhythmias in patients with implantable cardioverter-defibrillators (ICDs) adversely affect outcomes. Antiarrhythmic approaches to ventricular tachycardia (VT) have variable efficacy and may increase risk of ventricular arrhythmias, worsening cardiomyopathy, and death. Comparatively, VT ablation is an alternative approach that may favorably affect outcomes. OBJECTIVE: To further explore the effect on long-term outcomes after catheter ablation of VT, we compared patients with history of ICD shocks who did not undergo ablation, patients with a history of ICD shocks that underwent ablation, and patients with ICDs who had no history of ICD shocks. METHODS: A total of 102 consecutive patients with structural heart disease who underwent VT ablation for recurrent ICD shocks were compared with 2088 patients with ICDs and no history of appropriate shocks and 817 patients with ICDs and a history of appropriate shocks for VT or ventricular fibrillation. Outcomes considered were mortality, heart failure hospitalization, atrial fibrillation, and stroke/transient ischemic attack. RESULTS: The mean age of 3007 patients was 65.4 ± 13.9 years. Over long-term follow-up, 866 (28.8%) died, 681 (22.7%) had a heart failure admission, 706 (23.5%) developed new-onset atrial fibrillation, and 224 (7.5%) had a stroke. The multivariate-adjusted risks of deaths and heart failure hospitalizations were higher in patients with history of ICD shocks who were treated medically than in patients with ICDs and no history of shock (hazard ratio [HR] 1.45; P < .0001 vs HR 2.00; P < .0001, respectively). The multivariate-adjusted risks were attenuated after VT ablation with death and heart failure hospitalization rates similar to those of patients with no shock (HR 0.89; P = .58 vs HR 1.38; P = .09, respectively). A similar nonsignificant trend was seen with stroke/transient ischemic attack. CONCLUSIONS: Patients treated with VT ablation after an ICD shock have a significantly lower risk of death and heart failure hospitalization than did patients managed medically only. The adverse event rates after VT ablation were similar to those of patients with ICDs but without VT.

The evolution of the cardiac implantable electronic device connector.

Cardiac implantable electronic devices (CIEDs) play a vital role in the management of cardiac rhythm disturbances. The devices are comprised of two primary components: a generator and lead joined by a connector. Original pacemaker lead connectors were created de novo at the time of implantation or replacement and were very unreliable. With the development of new lead designs, creation of a standard connector configuration, the IS-1 connector became mandatory. Similar connector development also occurred with the advent of the implantable cardioverter defibrillator (ICD), resulting in creation of the high voltage standard: the DF-1 connector. Differing from a pacemaker lead, the ICD lead connector requires one IS-1 connector and one or two DF-1 connectors, resulting in a large cumbersome lead connector and generator header block. Recently, a revolutionary quad pole single plug connector standard has been approved for market release. These are the single-pin DF4 and IS4 lead connectors that carry low- and high-voltage poles or all low-voltage poles, respectively. These connectors, together with new labeling guidelines, have simplified operative procedures and reduced errors, when mating lead connectors into the generator's connector block.

Supraventricular arrhythmias in patients with cardiac sarcoidosis prevalence, predictors, and clinical implications.

BACKGROUND: Cardiac sarcoidosis (CS) is known to be associated with congestive heart failure, conduction disorders, and tachyarrhythmias. Ventricular arrhythmias are the most feared cardiac manifestation because they often are unpredictable, may be the fi rst manifestation of the disease, and may be fatal. The propensity for the development of supraventricular arrhythmias (SVAs) in patients with CS has not been described. The aim of this study was to assess the prevalence as well as the predictors of SVA. METHODS: We retrospectively investigated 100 patients with biopsy specimen-proven systemic sarcoidosis and evidence of cardiac involvement (defi ned by cardiac biopsy specimen, PET scan, or cardiac MRI). The mean follow-up was 5.8 3.6 years. ECG, Holter monitoring, implantable cardioverter defibrillator interrogations, or electrophysiology studies were used to document SVA. Echocardiographic data, demographics, and extracardiac involvement were recorded, and univariate and Poisson regressions were performed to compare characteristics of patients with and without documented SVA. RESULTS: The prevalence of SVA was 32%, and atrial fibrillation was the most common arrhythmia, comprising 18% of the total burden, followed by atrial tachycardias (7%), atrial fl utter (5%), and other supraventricular tachycardias (2%). Of the patients with SVA, 96% were symptomatic. Left atrial enlargement (LAE) was more frequent in the group with SVA, with an incidence of 267.8 per 1,000 person-years, and it significantly increased the likelihood of SVA on multivariate analysis (risk ratio, 6.12; 95% CI, 2.19-17.11). Diastolic dysfunction, systemic hypertension, and right atrial enlargement were predictors of SVA on univariate analysis. Left ventricular hypertrophy, right ventricular dysfunction, tricuspid valve disease, pulmonary hypertension, and pulmonary sarcoidosis were not associated with SVA on univariate analysis. CONCLUSIONS: The study systematically evaluated the frequency of SVA in a large number of patients with CS. SVA in patients with CS is frequent and associated with symptoms. LAE was clearly associated with the development of SVA in this patient population. The extent to which LAE predicts the occurrence of SVA in larger, more diverse CS populations should be evaluated prospectively.

Contribution of ethylenetetrafluoroethylene (ETFE) insulation to the electrical performance of Riata® silicone leads having externalized conductors.

BACKGROUND: The insulation of St. Jude Medical Riata® leads contains a polytetrafluoroethylene (PTFE) liner, silicone tubing, and ethylenetetrafluoroethylene (ETFE) coating on individual cable conductors. ETFE has sufficient dielectric strength to assure electrical function. This investigation intended to analyze performance of leads with and without externalized conductors and with intact and breached ETFE. METHODS: Testing was performed on ETFE-coated conductors to determine their ability to deliver high-voltage therapy. Tests were performed on samples under different conditions and current leakage was measured. A high-voltage test and a cyclic pulse test were performed, and the effect of lead modifications on the potential gradient from a high-voltage shock was used to determine functionality. Measurements from modified Riata® leads were compared with a control lead with all insulation and conducting elements intact. RESULTS: Current leakage for all conditions tested, was within the acceptance criteria for the high-voltage test and the cyclic pulse test. In conductors that underwent cyclic testing, the highest value of current leakage was within the limit of acceptability for both phases of the test. Testing of leads with externalized conductors and breached ETFE showed similar potential gradients compared with a control lead. CONCLUSIONS: Testing of ETFE-coated conductors following multiple preconditioning steps showed that ETFE serves as a redundant layer of insulation. In the event that the ETFE coating is breached, the potential gradient seen resulting from a high-voltage defibrillation shock was similar to a lead with no breach to the ETFE, even after 100 shocks.