Efficacy and Safety of Appropriate Shocks and Antitachycardia Pacing in Transvenous and Subcutaneous Implantable Defibrillators: Analysis of All Appropriate Therapy in the PRAETORIAN Trial.

BACKGROUND: The PRAETORIAN trial (A Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy) showed noninferiority of subcutaneous implantable cardioverter defibrillator (S-ICD) compared with transvenous implantable cardioverter defibrillator (TV-ICD) with regard to inappropriate shocks and complications. In contrast to TV-ICD, S-ICD cannot provide antitachycardia pacing for monomorphic ventricular tachycardia. This prespecified secondary analysis evaluates appropriate therapy and whether antitachycardia pacing reduces the number of appropriate shocks. METHODS: The PRAETORIAN trial was an international, investigator-initiated randomized trial that included patients with an indication for implantable cardioverter defibrillator (ICD) therapy. Patients with previous ventricular tachycardia <170 bpm or refractory recurrent monomorphic ventricular tachycardia were excluded. In 39 centers, 849 patients were randomized to receive an S-ICD (n=426) or TV-ICD (n=423) and were followed for a median of 49.1 months. ICD programming was mandated by protocol. Appropriate ICD therapy was defined as therapy for ventricular arrhythmias. Arrhythmias were classified as discrete episodes and storm episodes (≥3 episodes within 24 hours). Analyses were performed in the modified intention-to-treat population. RESULTS: In the S-ICD group, 86 of 426 patients received appropriate therapy, versus 78 of 423 patients in the TV-ICD group, during a median follow-up of 52 months (48-month Kaplan-Meier estimates 19.4% and 17.5%; P=0.45). In the S-ICD group, 83 patients received at least 1 shock, versus 57 patients in the TV-ICD group (48-month Kaplan-Meier estimates 19.2% and 11.5%; P=0.02). Patients in the S-ICD group had a total of 254 shocks, compared with 228 shocks in the TV-ICD group (P=0.68). First shock efficacy was 93.8% in the S-ICD group and 91.6% in the TV-ICD group (P=0.40). The first antitachycardia pacing attempt successfully terminated 46% of all monomorphic ventricular tachycardias, but accelerated the arrhythmia in 9.4%. Ten patients with S-ICD experienced 13 electrical storms, versus 18 patients with TV-ICD with 19 electrical storms. Patients with appropriate therapy had an almost 2-fold increased relative risk of electrical storms in the TV-ICD group compared with the S-ICD group (P=0.05). CONCLUSIONS: In this trial, no difference was observed in shock efficacy of S-ICD compared with TV-ICD. Although patients in the S-ICD group were more likely to receive an ICD shock, the total number of appropriate shocks was not different between the 2 groups. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01296022.

Subcutaneous or Transvenous Defibrillator Therapy.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (ICD) was designed to avoid complications related to the transvenous ICD lead by using an entirely extrathoracic placement. Evidence comparing these systems has been based primarily on observational studies. METHODS: We conducted a noninferiority trial in which patients with an indication for an ICD but no indication for pacing were assigned to receive a subcutaneous ICD or transvenous ICD. The primary end point was the composite of device-related complications and inappropriate shocks; the noninferiority margin for the upper boundary of the 95% confidence interval for the hazard ratio (subcutaneous ICD vs. transvenous ICD) was 1.45. A superiority analysis was prespecified if noninferiority was established. Secondary end points included death and appropriate shocks. RESULTS: A total of 849 patients (426 in the subcutaneous ICD group and 423 in the transvenous ICD group) were included in the analyses. At a median follow-up of 49.1 months, a primary end-point event occurred in 68 patients in the subcutaneous ICD group and in 68 patients in the transvenous ICD group (48-month Kaplan-Meier estimated cumulative incidence, 15.1% and 15.7%, respectively; hazard ratio, 0.99; 95% confidence interval [CI], 0.71 to 1.39; P = 0.01 for noninferiority; P = 0.95 for superiority). Device-related complications occurred in 31 patients in the subcutaneous ICD group and in 44 in the transvenous ICD group (hazard ratio, 0.69; 95% CI, 0.44 to 1.09); inappropriate shocks occurred in 41 and 29 patients, respectively (hazard ratio, 1.43; 95% CI, 0.89 to 2.30). Death occurred in 83 patients in the subcutaneous ICD group and in 68 in the transvenous ICD group (hazard ratio, 1.23; 95% CI, 0.89 to 1.70); appropriate shocks occurred in 83 and 57 patients, respectively (hazard ratio, 1.52; 95% CI, 1.08 to 2.12). CONCLUSIONS: In patients with an indication for an ICD but no indication for pacing, the subcutaneous ICD was noninferior to the transvenous ICD with respect to device-related complications and inappropriate shocks. (Funded by Boston Scientific; PRAETORIAN ClinicalTrials.gov number, NCT01296022.).

Voltage gradients in transvenous and subcutaneous defibrillation and their risk of myocardial damage.

INTRODUCTION: Transvenous implantable cardioverter-defibrillator (ICD) shocks have been associated with cardiac biomarker elevations and are thought in some cases to contribute to adverse clinical outcomes and mortality, possibly from myocardium exposed to excessive shock voltage gradients. Currently, there are only limited data for comparison with subcutaneous ICDs. We sought to compare ventricular myocardium voltage gradients resulting from transvenous (TV) and subcutaneous defibrillator (S-ICD) shocks to assess their risk of myocardial damage. METHODS: A finite element model was derived from thoracic magnetic resonance imaging (MRI). Voltage gradients were modeled for an S-ICD with a left-sided parasternal coil and a left-sided TV-ICD with a mid-cavity, a septal right ventricle (RV) coil, or a dual coil lead (TV mid, TV septal, TV septal + superior vena cava [SVC]). High gradients were defined as > 100 V/cm. RESULTS: The volumes of ventricular myocardium with high gradients > 100 V/cm were 0.02, 2.4, 7.7, and 0 cc for TV mid, TV septal, TV septal + SVC, and S-ICD, respectively. CONCLUSION: Our models suggest that S-ICD shocks produce more uniform gradients in the myocardium, with less exposure to potentially damaging electrical fields, compared to TV-ICDs. Dual coil TV leads yield higher gradients, as does closer proximity of the shock coil to the myocardium.

Device-related complications in subcutaneous versus transvenous ICD: a secondary analysis of the PRAETORIAN trial.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) is developed to overcome lead-related complications and systemic infections, inherent to transvenous ICD (TV-ICD) therapy. The PRAETORIAN trial demonstrated that the S-ICD is non-inferior to the TV-ICD with regard to the combined primary endpoint of inappropriate shocks and complications. This prespecified secondary analysis evaluates all complications in the PRAETORIAN trial. METHODS AND RESULTS: The PRAETORIAN trial is an international, multicentre, randomized trial in which 849 patients with an indication for ICD therapy were randomized to receive an S- ICD (N = 426) or TV-ICD (N = 423) and followed for a median of 49 months. Endpoints were device-related complications, lead-related complications, systemic infections, and the need for invasive interventions. Thirty-six device-related complications occurred in 31 patients in the S-ICD group of which bleedings were the most frequent. In the TV-ICD group, 49 complications occurred in 44 patients of which lead dysfunction was most frequent (HR: 0.69; P = 0.11). In both groups, half of all complications were within 30 days after implantation. Lead-related complications and systemic infections occurred significantly less in the S-ICD group compared with the TV-ICD group (P < 0.001, P = 0.03, respectively). Significantly more complications required invasive interventions in the TV-ICD group compared with the S-ICD group (8.3% vs. 4.3%, HR: 0.59; P = 0.047). CONCLUSION: This secondary analysis shows that lead-related complications and systemic infections are more prevalent in the TV-ICD group compared with the S-ICD group. In addition, complications in the TV-ICD group were more severe as they required significantly more invasive interventions. This data contributes to shared decision-making in clinical practice.

Complications related to elective generator replacement of the subcutaneous implantable defibrillator.

AIMS: To guarantee uninterrupted function of the subcutaneous implantable cardioverter-defibrillator (S-ICD), the pulse generator needs to be surgically replaced before the battery is depleted. The risks related to this replacement substantially impact long-term outcome for S-ICD recipients, as the majority will undergo one or several of these procedures in their lifetime. We aim to describe the procedural characteristics of the replacement procedure and to provide an insight in the complications associated with these replacements. METHODS AND RESULTS: In this retrospective analysis, data from replacement procedures and follow-up visits were collected from all patients who underwent elective S-ICD generator replacement in our tertiary centre from June 2014 until November 2019. Original device position was assessed using the PRAETORIAN score. Complications were defined as those requiring surgical intervention, systemic antibiotic treatment, or device extraction. Seventy-two patients were included, with a median follow-up of 1.9 years (IQR 0.6-3.3 years) after replacement. Battery depletion occurred after 5.9 ± 0.7 years. The pulse generator was repositioned in patients with a PRAETORIAN score ≥90 to minimize the defibrillation threshold. Although there was an increase in impedance compared to the implant procedure, first shock conversion rate during defibrillation testing was 91.4% with a success rate of 100% after multiple attempts. Two patients developed a complication after, respectively, 9 and 21 months, resulting in a complication rate of 1.4% per year. CONCLUSION: With a median follow-up of 1.9 years, this study shows a low complication rate after S-ICD replacement, with a first shock conversion rate of 91.4%.

Long-term follow-up of the two-incision implantation technique for the subcutaneous implantable cardioverter-defibrillator.

INTRODUCTION: The two-incision implantation technique of the subcutaneous implantable cardioverter-defibrillator (S-ICD) was introduced as an alternative to the standard three-incision approach by omitting the superior parasternal incision. Thereby, complications may be prevented. Short-term follow-up demonstrated the safety and efficacy of the two-incision technique. However, long-term results are lacking. METHODS: This retrospective study included patients implanted between February 2009 and June 2020. Patients were divided into a group of patients who were implanted with the standard three-incision technique and a group who were implanted with the two-incision technique. Outcomes were defibrillation impedance and efficacy and complications requiring intervention. RESULTS: A total of 268 patients were included (age 42.4 ± 16.6 years, 35.4% female, BMI 25.1 ± 4.5 kg/m2 ). Thirty-one patients underwent S-ICD implantation with the three-incision technique and 237 patients with the two-incision technique. First shock efficacy during defibrillation testing was 93% in the three-incision group versus 94% in the two-incision group (P = .69), and shock impedance was 85 versus 68 ohms (P = .04). First shock success was 75% versus 76% for spontaneous episodes (P = 1.00). Complication-free survival at 5-year follow-up in the three-incision group was estimated at 0.96 (95% CI 0.90-1.00) versus 0.98 (95% CI 0.96-1.00) in the two-incision group (P = .20) and for inappropriate shocks at 5-year 0.77 (95% CI 0.63-0.94) versus 0.83 (95% CI 0.77-0.89, P = .30), respectively. CONCLUSION: Five-year follow-up in this S-ICD cohort showed similar complication rates and effectiveness of two-incision technique compared to the three-incision technique. This technique offers physicians a less invasive and more simplified implantation procedure for the S-ICD, with a better cosmetic result.

Rationale and design of the PRAETORIAN-DFT trial: A prospective randomized CompArative trial of SubcutanEous ImplanTable CardiOverter-DefibrillatoR ImplANtation with and without DeFibrillation testing.

In transvenous implantable cardioverter-defibrillator (TV-ICD) implants, routine defibrillation testing (DFT) does not improve shock efficacy or reduce arrhythmic death but patients are exposed to the risk of complications related to DFT. The conversion rate of DFT in subcutaneous ICD (S-ICD) is high and first shock efficacy is similar to TV-ICD efficacy rates. STUDY DESIGN: The PRAETORIAN-DFT trial is an investigator-initiated, randomized, controlled, multicenter, prospective two-arm trial designed to demonstrate non-inferiority of omitting DFT in patients undergoing S-ICD implantation in which the S-ICD system components are optimally positioned. Positioning of the S-ICD will be assessed with the PRAETORIAN score. The PRAETORIAN score is developed to systematically evaluate implant position of the S-ICD system components which determine the defibrillation threshold on post-operative chest X-ray. A total of 965 patients, scheduled to undergo a de novo S-ICD implantation without contra-indications for either DFT strategy, will be randomized to either standard of care S-ICD implantation with DFT, or S-ICD implantation without DFT but with evaluation of the implant position using the PRAETORIAN score. The study is powered to claim non-inferiority of S-ICD implantation without DFT in de novo S-ICD patients in respect to the primary endpoint of first shock efficacy in spontaneous arrhythmia episodes. Patients with a high PRAETORIAN score (≥90) in the interventional arm of this study will undergo DFT according to the same DFT protocol as in the control arm. CONCLUSION: The PRAETORIAN-DFT trial is a randomized trial that aims to gain scientific evidence to safely omit a routine DFT after S-ICD implantation in patients with correct device positioning.

J Curve in Patients Randomly Assigned to Different Systolic Blood Pressure Targets: An Experimental Approach to an Observational Paradigm.

BACKGROUND: Low systolic blood pressure (SBP) values are associated with an increased risk of cardiovascular events, giving rise to the so-called J-curve phenomenon. We assessed the association between on-treatment SBP levels, cardiovascular events, and all-cause mortality in patients randomized to different SBP targets. METHODS: Data from 2 large randomized trials that randomly allocated hypertensive patients at high risk for cardiovascular disease to intensive (SBP<120 mm Hg) or conventional (SBP<140 mm Hg) treatment were pooled and harmonized for outcomes and follow-up duration. Using natural cubic splines, we plotted the hazard ratio for all-cause mortality and cardiovascular events against the mean on-treatment SBP per treatment group. RESULTS: The pooled data consisted of 194 875 on-treatment SBP measurements in 13 946 patients (98.9%). During a median follow-up of 3.3 years, cardiovascular events occurred in 1014 patients (7.3%), and 502 patients died (3.7%). For both blood pressure targets, an identical shape of the J curve was present, with a nadir for cardiovascular events and all-cause mortality just below the SBP target. Patients in the lowest SBP stratum were older, had a higher body mass index, smoked more often, and had a higher frequency of diabetes mellitus and cardiovascular events. CONCLUSIONS: Low on-treatment SBP levels are associated with increased cardiovascular events and all-cause mortality. This association is independent of the attained blood pressure level because the J curve aligns with the SBP target. Our results suggest that the benefit or risk associated with intensive blood pressure-lowering treatment can be established only via randomized clinical trials. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifiers: NCT01206062 and NCT00000620.

Propensity score matched comparison of subcutaneous and transvenous implantable cardioverter-defibrillator therapy in the SIMPLE and EFFORTLESS studies.

Aims: Comparison of outcomes between subcutaneous and transvenous implantable cardioverter-defibrillator (S-ICD and TV-ICD) therapy is hampered by varying patient characteristics and complication definitions. The aim of this analysis is to compare clinical outcomes of S-ICD and TV-ICD therapy in a matched cohort. Methods and results: Patients implanted with de novo implantable cardioverter-defibrillators without need for pacing were selected from two studies: SIMPLE (n = 1091 single and n = 553 dual chamber TV-ICDs) and EFFORTLESS (n = 798 S-ICDs). Subcutaneous implantable cardioverter-defibrillator patients were 1:1 matched on propensity score to TV-ICD patients. Propensity scores were calculated using 15 baseline characteristics including diagnosis. The Kaplan-Meier estimates for complications requiring invasive intervention, appropriate shocks, and inappropriate shocks were calculated at 3 years follow-up. The primary analysis yielded 391 patients pairs with balanced baseline characteristics, with mean age 55 ± 14 years, 49% ischaemic cardiomyopathy, mean left ventricular ejection fraction 40%, 71% primary prevention, and 89% of TV-ICDs were single chamber. Follow-up was mean 2.9 years in the S-ICD arm vs. 3.3 in the TV-ICD arm. All-cause complications occurred in 9.0% of S-ICD vs. 6.5% of TV-ICD patients, P = 0.29. Appropriate shocks occurred in 9.9% of S-ICD vs. 13.8% in TV-ICD patients, P = 0.03 and inappropriate shocks in 11.9% in S-ICD vs. 8.9% in TV-ICD patients (P = 0.07). Total shock burden (20 vs. 31, P = 0.05) and appropriate shock burden per 100 patients years (9 vs. 18, P = 0.02) were lower for S-ICD patients, while inappropriate shock burden was equal (11 vs. 13, P = 0.56). Conclusion: The earliest experience of the S-ICD demonstrates similar outcomes as contemporary TV-ICD therapy in a matched comparison with predominately single-chamber devices at 3 years follow-up.

Clinical parameters to optimize patient selection for subcutaneous and transvenous implantable defibrillator therapy.

BACKGROUND: The subcutaneous implantable cardioverter-defibrillator (S-ICD) lacks the antitachycardia pacing (ATP) capability of tranvenous ICDs (TV-ICD). S-ICD patient selection can be challenging as some patients may benefit from ATP. We aim to identify clinical predictors of ATP benefit, in order to improve patient selection for S-ICD or TV-ICD therapy. METHODS: De novo single- and dual-chamber TV-ICD patients implanted between March 2011 and December 2015 were included. Ventricular arrhythmias terminated by ATP and not followed by a shock were considered successful ATP therapy. Cox proportional hazard analysis was performed to assess the adjusted effect of multiple predictors for appropriate ATP and shock therapy. RESULTS: Note that 431 patients were included with a median follow-up of 26 months. Ninety-nine patients (23%) received appropriate ATP therapy, which terminated the arrhythmia in 67%. A history of nonsustained ventricular tachycardia (NSVT) or monomorphic VT (MVT) was the only predictor of appropriate ATP therapy in the multivariable model (hazard ratio [HR] 2.73, P < 0.001). Sixty-five of 221 patients with a history of NS (VT) received appropriate ATP (29%) versus 24 patients (11%) without a history NS (VT) (P < 0.001). A secondary prevention indication was the only predictor in the multivariate model for appropriate shock therapy (HR 1.82, P  =  0.05). CONCLUSION: A history of NSVT or MVT is a significant predictor for appropriate and successful ATP therapy. One in three patients with NSVT or MVT received appropriate ATP versus one in 10 patients without a history of NSVT or MVT over a 2-year period of follow-up.

Assessment of the Extravascular Implantable Defibrillator: Feasibility of Substernal Ventricular Pacing.

INTRODUCTION: The objective of this study was to assess feasibility of ventricular pacing and thresholds from within the substernal space to examine a new extravascular ICD configuration with pacing capabilities. METHODS: In patients undergoing midline sternotomy, a duodecapolar diagnostic pacing catheter was positioned in the substernal space anterior to the pericardium, and a cutaneous patch in left lateral position. Different unipolar and bipolar pacing configurations were assessed. Strength-duration curves were performed to identify the optimal output, starting at 25 mA with a pulse width of 10 milliseconds. RESULTS: Eight patients with mean age 69 ± 9 years were included. In 5, ventricular capture was achieved in ≥1 configuration. The mean bipolar pacing thresholds at PW 10, 5, 3, 1 milliseconds were 12.4 ± 3.7 mA (5 patients), 13.3 ± 5.8 mA (3 patients), 18.3 ± 5.7 mA (3 patients), and 25 ± 0 mA (2 patients), respectively. The 60-mm electrode spacing was the most successful bipolar configuration. Unipolar pacing was successful in 3 out of 4 patients with mean thresholds of 10 ± 0 mA at 10 milliseconds (3 patients), 15 ± 0 mA at 5 milliseconds (3 patients), 16.7 ± 2.9 mA at 3 milliseconds (3 patients), and 20 ± 7.1 mA at 1 milliseconds (2 patients). CONCLUSION: Ventricular pacing from the substernal space in patients with midline sternotomy is feasible. Closed sternum studies are needed to determine pacing thresholds more accurately.

Implantable cardioverter-defibrillators in adults with congenital heart disease: a systematic review and meta-analysis.

AIMS: Sudden cardiac death is a major cause of mortality in adult congenital heart disease (ACHD) patients. The indications for implantable cardioverter-defibrillator (ICD) implantation in ACHD patients are still not well established. We aim to systematically review the literature on indications and outcome of ICD implantation in ACHD patients. METHODS AND RESULTS: We performed a comprehensive search in EMBASE, MEDLINE, and Google Scholar to identify all studies on ICD implantation in ACHD patients. We used random effects models to calculate proportions and 95% confidence intervals. Of 1356 articles, 24 studies with 2162 patients were included, with a mean follow-up of 3.6 ± 0.9 years. Half of patients had tetralogy of Fallot. Mean age at implantation was 36.5 ± 5.5 years old and 66% was male. Implantable cardioverter-defibrillators were implanted for primary prevention in 53% (43.5-62.7). Overall, 24% (18.6-31.3) of patients received one or more appropriate ICD interventions (anti-tachycardia pacing or shocks) during 3.7 ± 0.9 years: 22% (16.9-28.8) of patients with primary prevention in 3.3 ± 0.3 years and 35% (26.6-45.2) of patients with secondary prevention in 4.3 ± 1.2 years. Inappropriate shocks occurred in 25% (20.1-31.0) in 3.7 ± 0.8 years and other, particularly lead-related complications in 26% (18.9-33.6) of patients in 3.8 ± 0.8 years. All-cause mortality was 10% during 3.7 ± 0.9 years. CONCLUSIONS: In ACHD, remarkably high rates of appropriate ICD therapy were reported, both in primary and secondary prevention. Because of the young age and lower death rates, the cumulative beneficial effects are likely greater in ACHD patients than in acquired heart disease patients. However, considering the high rates of inappropriate shocks and complications, case-by-case weighing of costs and benefits, remains essential.

Association Between Chest Compression Interruptions and Clinical Outcomes of Ventricular Fibrillation Out-of-Hospital Cardiac Arrest.

BACKGROUND: Minimizing pauses in chest compressions during cardiopulmonary resuscitation is a focus of current guidelines. Prior analyses found that prolonged pauses for defibrillation (perishock pauses) are associated with worse survival. We analyzed resuscitations to characterize the association between pauses for all reasons and both ventricular fibrillation termination and patient survival. METHODS AND RESULTS: In 319 patients with ventricular tachycardia/fibrillation out-of-hospital cardiac arrest, we analyzed recordings from all defibrillators used during resuscitation and measured durations of all cardiopulmonary resuscitation pauses. Median durations were 32 seconds (25th and 75th percentile, 22 and 52 seconds) for the longest pause for any reason, 23 seconds (25th and 75th percentile, 14 and 34 seconds) for the longest perishock pause, and 24 seconds (25th and 75th percentile, 11 and 38 seconds) for the longest nonshock pause. Multivariable regression models showed lower odds for survival per 5-second increase in the longest overall pause (odds ratio, 0.89; 95% confidence interval, 0.83-0.95), longest perishock pause (odds ratio, 0.85; 95% confidence interval, 0.77-0.93), and longest nonshock pause (odds ratio, 0.83; 95% confidence interval, 0.75-0.91). In 36% of cases, the longest pause was a nonshock pause; this subgroup had lower survival than the group in whom the longest pause was a perishock pause (27% versus 44%, respectively; P<0.01) despite a higher chest compression fraction. Preshock pauses were 8 seconds (25th and 75th percentile, 4 and 17 seconds) for shocks that terminated ventricular fibrillation and 7 seconds (25th and 75th percentile, 4 and 13 seconds) for shocks that did not (P=0.18). CONCLUSIONS: Prolonged pauses have a negative association with survival not explained by chest compression fraction or decreased ventricular fibrillation termination rate. Ventricular fibrillation termination was not the mechanism linking pause duration and survival. Strategies shortening the longest pauses may improve outcome.

The learning curve associated with the introduction of the subcutaneous implantable defibrillator.

AIMS: The subcutaneous implantable cardioverter defibrillator (S-ICD) was introduced to overcome complications related to transvenous leads. Adoption of the S-ICD requires implanters to learn a new implantation technique. The aim of this study was to assess the learning curve for S-ICD implanters with respect to implant-related complications, procedure time, and inappropriate shocks (IASs). METHODS AND RESULTS: In a pooled cohort from two clinical S-ICD databases, the IDE Trial and the EFFORTLESS Registry, complications, IASs at 180 days follow-up and implant procedure duration were assessed. Patients were grouped in quartiles based on experience of the implanter and Kaplan-Meier estimates of complication and IAS rates were calculated. A total of 882 patients implanted in 61 centres by 107 implanters with a median of 4 implants (IQR 1,8) were analysed. There were a total of 59 patients with complications and 48 patients with IAS. The complication rate decreased significantly from 9.8% in Quartile 1 (least experience) to 5.4% in Quartile 4 (most experience) (P = 0.02) and non-significantly for IAS from 7.9 to 4.8% (P = 0.10). Multivariable analysis demonstrated a hazard ratio of 0.78 (P = 0.045) for complications and 1.01 (P = 0.958) for IAS. Dual-zone programming increased with experience of the individual implanter (P < 0.001), which reduced IAS significantly in the multivariable model (HR 0.44, P = 0.01). Procedure time decreased from 75 to 65 min (P < 0.001). The complication rate and procedure time stabilized after Quartile 2 (>13 implants). CONCLUSION: There is a short and significant learning curve associated with physicians adopting the S-ICD. Performance stabilizes after 13 implants.

Subcutaneous Implantable Cardioverter Defibrillator Lead Failure due to Twiddler Syndrome.

We present a case of Twiddler syndrome in a patient with a subcutaneous implantable cardioverter defibrillator (S-ICD). The patient presented herself to the outpatient clinic with pain in the left chest. Chest x-ray confirmed Twiddler syndrome and ICD read-out revealed lead failure resulting in absent heart rhythm sensing in one vector. The lead and pulse generator were extracted and a new S-ICD system was reimplanted submuscular underneath the serratus anterior muscle to prevent reoccurrence. Lead investigation revealed an insulation defect caused by excessive mechanical stress.

Predictive value of the PRAETORIAN score for defibrillation test success in patients with subcutaneous ICD: A subanalysis of the PRAETORIAN-DFT trial.

BACKGROUND: The PRAETORIAN score estimates the risk of failure of subcutaneous implantable cardioverter-defibrillator (S-ICD) therapy by using generator and lead positioning on bidirectional chest radiographs. The PRospective randomized compArative trial of subcutanEous implanTable cardiOverter-defibrillatoR ImplANtation with and without DeFibrillation Testing (PRAETORIAN-DFT) investigates whether PRAETORIAN score calculation is noninferior to defibrillation testing (DFT) with regard to first shock efficacy in spontaneous events. OBJECTIVE: This prespecified subanalysis assessed the predictive value of the PRAETORIAN score for defibrillation success in induced ventricular arrhythmias. METHODS: This multicenter investigator-initiated trial randomized 965 patients between DFT and PRAETORIAN score calculation after de novo S-ICD implantation. Successful DFT was defined as conversion of induced ventricular arrhythmia in <5 seconds from shock delivery within 2 attempts. Bidirectional chest radiographs were obtained after implantation. The predictive value of the PRAETORIAN score for DFT success was calculated for patients in the DFT arm. RESULTS: In total, 482 patients were randomized to undergo DFT. Of these patients, 457 (95%) underwent DFT according to protocol, of whom 445 (97%) had successful DFT and 12 (3%) had failed DFT. A PRAETORIAN score of ≥90 had a positive predictive value of 25% for failed DFT, and a PRAETORIAN score of <90 had a negative predictive value of 99% for successful DFT. A PRAETORIAN score of ≥90 was the strongest independent predictor for failed DFT (odds ratio 33.77; confidence interval 6.13-279.95; P < .001). CONCLUSION: A PRAETORIAN score of <90 serves as a reliable indicator for DFT success in patients with S-ICD, and a PRAETORIAN score of ≥90 is a strong predictor for DFT failure.

Association Between Self-Rated Medication Adherence and Adverse Cardiovascular Outcomes in Patients With Hypertension.

Background Medication nonadherence contributes to poor health outcomes but remains challenging to identify. This study assessed the association between self-rated adherence and systolic blood pressure, low-density lipoprotein cholesterol levels, cardiovascular events, and all-cause mortality in SPRINT (Systolic Blood Pressure Intervention Trial). Methods and Results A total of 9361 patients randomized to 2 systolic blood pressure target groups, <120 mm Hg (intensive) and <140 mm Hg (standard), self-rated their medication adherence at each visit by marking a scale, ranging from 0% to 100%. Lower and high adherence were defined as scores ≤80% and >80%, respectively. Linear mixed effect regression models and Cox proportional hazard models were used to evaluate the association between self-rated adherence and systolic blood pressure and low-density lipoprotein cholesterol and cardiovascular events and all-cause mortality, respectively. A total of 9278 participants (mean age 68±9.4 years, 35.6% female) had repeated self-rated adherence measurements available, with a mean of 15±4 measurements per participant over 3.8 years follow-up. Of these, 2694 participants (29.0%) had ≥1 adherence measurements ≤80%. Compared with high-adherent patients, patients with lower adherence had significantly higher estimated on-treatment systolic blood pressure at 2-year follow-up: 128.7 (95% CI, 127.6-129.9) versus 120.0 (95% CI, 119.7-120.2) mm Hg in the intensive arm; and 139.8 (95% CI 138.4-141.1) versus 135.0 (95% CI 134.7-135.2) in the standard arm. Moreover, lower adherence was associated with an estimated 11 mg/dL higher low-density lipoprotein cholesterol level, more cardiovascular events (hazard ratio [HR], 1.69 [95% CI, 1.20-2.39]), and higher all-cause mortality (HR, 1.63 [95% CI, 1.16-2.31]). Conclusions Self-rated adherence allows identification of lower medication adherence and correlates with blood pressure control, low-density lipoprotein cholesterol levels, and adverse outcomes.

Initial Estimated Glomerular Filtration Rate Decline and Long-Term Renal Function During Intensive Antihypertensive Therapy: A Post Hoc Analysis of the SPRINT and ACCORD-BP Randomized Controlled Trials.

Lowering blood pressure (BP) can lead to an initial decline in estimated glomerular filtration rate (eGFR). However, there is debate how much eGFR decline is acceptable. We performed a post hoc analysis of ACCORD-BP (Action to Control Cardiovascular Risk in Diabetes-Blood Pressure) and SPRINT (Systolic Blood Pressure Intervention Trial), which randomized patients to intensive or standard systolic BP-targets. We determined the relation between initial decline in mean arterial pressure and eGFR. Subsequently, we stratified patients to BP-target and initial eGFR decrease and assessed the relation with annual eGFR decline after 1 year. A total of 13 266 patients with 41 126 eGFR measurements were analyzed. Up to 10 mm Hg of BP-lowering, eGFR did not change. Hereafter, there was a linear decrease of 3.4% eGFR (95% CI, 2.9%-3.9%) per 10 mm Hg mean arterial pressure decrease. The observed eGFR decline based on 95% of the subjects varied from 26% after 0 mm Hg to 46% with a 40 mm Hg mean arterial pressure decrease. There was no difference in eGFR slope (P=0.37) according to initial eGFR decline and BP-target, with a decrease of 1.24 (95% CI, 1.09-1.39), 1.20 (95% CI, 0.97-1.43), and 1.14 (95% CI, 0.77-1.50) in the 5%, 5% to 20%, and >20% stratum during intensive and 0.95 (95% CI, 0.81-1.09), 1.23 (95% CI, 0.97-1.49), and 1.17 (95% CI, 0.65-1.69) mL/minute per 1.73 m2 per year during standard treatment. In patients at high cardiovascular risk with and without diabetes mellitus, we found no association between initial eGFR and annual eGFR decline during BP-lowering treatment. Our results support that an eGFR decrease up to 20% after BP lowering can be accepted and suggest that the limit can be extended up to 46% depending on the achieved BP reduction. Registration- URL: https://www.clinicaltrials.gov; Unique identifier: NCT00000620, NCT01206062.