Safety of ventricular arrhythmia radiofrequency ablation with half-normal saline irrigation.

AIMS: Failure of radiofrequency (RF) ablation of ventricular arrhythmias is often due to inadequate lesion size. Irrigated RF ablation with half-normal saline (HNS) has the potential to increase lesion size and reduce sodium delivery to the patient if the same volume of RF irrigant were used for normal saline (NS) and HNS but could increase risks related to steam pops and lesion size. This study aims to assess periprocedural complications and acute ablation outcome of ventricular arrhythmias ablation with HNS. METHODS AND RESULTS: Prospective assessment of outcomes was performed in 1024 endocardial and/or epicardial RF ablation procedures in 935 consecutive patients (median age 64 years, 71.2% men, 73.4% cardiomyopathy, 47.2% sustained ventricular tachycardia). Half-normal saline was selected at the discretion of the treating physician. Radiofrequency ablation power was generally titrated to a ≤15â€…Ω impedance fall with intracardiac echocardiography monitoring. Half-normal saline was used in 900 (87.9%) and NS in 124 (12.1%) procedures. Any adverse event within 30 days occurred in 13.0% of patients treated with HNS RF ablation including 4 (0.4%) strokes/transient ischaemic attacks and 34 (3.8%) pericardial effusions requiring treatment (mostly related to epicardial access). Two steam pops with perforation required surgical repair (0.2%). Patients who received NS irrigation had less severe disease and arrhythmias. In multivariable models, adverse events and acute success of the procedure were not related to the type of irrigation. CONCLUSION: Half-normal saline irrigation RF ablation with power guided by impedance fall and intracardiac echocardiography has an acceptable rate of complications and acute ablation success while administering half of the saline load expected for NS irrigation.

Multicenter assessment of the outcomes of subcutaneous ICD implantation in patients with prior or future sternotomy.

BACKGROUND: The subcutaneous ICD (S-ICD) is a viable alternative to transvenous ICD and avoids intravascular complications in patients without a pacing indication. The outcomes of S-ICD implantation are uncertain in patients with prior sternotomy. OBJECTIVE: We aim to compare the implant techniques and outcomes with S-ICD implantation in patients with and without prior sternotomy. METHODS: Multicenter retrospective cohort study including adult patients with an S-ICD implanted between January 2014 and June 2020. Outcomes were compared between patients with and without prior sternotomy. RESULTS: Among the 212 patients (49 ± 15 years old, 43% women, BMI 30 ± 8 kg/m2 , 68% primary prevention, 30% ischemic cardiomyopathy, LVEF median 30% IQR 25%-45%) who underwent S-ICD implantation, 47 (22%) had a prior sternotomy. There was no difference in the sensing vector (57% vs. 53% primary, p = 0.55), laterality of the S-ICD lead to the sternum (94% vs. 96% leftward, p = 0.54), or the defibrillation threshold (65 ± 1.4 J vs. 65 ± 0.8 J, p = 0.76) with versus without prior sternotomy. The frequency of 30-day complications was similar with and without prior sternotomy (n = 3/47 vs. n = 15/165, 6% vs. 9%, p = 0.56). Over a median follow-up of 28 months (IQR 10-49 months), the frequency of inappropriate shocks was similar between those with and without prior sternotomy (n = 3/47 and n = 16/165, 6% vs. 10%, p = 0.58). CONCLUSION: Implantation of an S-ICD in patients with prior sternotomy is safe with a similar risk of 30-day complications and inappropriate ICD shocks as patients without prior sternotomy.

Durable pulmonary vein isolation with diffuse posterior left atrial ablation using low-flow, median power, short-duration strategy.

INTRODUCTION: To target posterior wall isolation (PWI) in atrial fibrillation (AF) ablation, diffuse ablation theoretically confers a lower risk of conduction recovery compared to box set. We sought to assess the safety and efficacy of diffuse PWI with low-flow, medium-power, and short-duration (LF-MPSD) ablation, and evaluate the durability of pulmonary vein isolation (PVI) and PWI among patients undergoing repeat ablations. METHODS: We retrospectively studied patients undergoing LF-MPSD ablation for AF (PVI + diffuse PWI) between August 2017 and December 2019. Clinical characteristics were collected. Kaplan-Meier survival analysis was performed to study AF/atrial flutter (AFL) recurrence. Ablation data were analyzed in patients who underwent a repeat AF/AFL ablation. RESULTS: Of the 463 patients undergoing LF-MPSD AF ablation (PVI alone, or PVI + diffuse PWI), 137 patients had PVI + diffuse PWI. Acute PWI with complete electrocardiogram elimination was achieved in 134 (97.8%) patients. Among the 126 patients with consistent follow-up, 38 (30.2%) patients had AF/AFL recurrence during a median duration of 14 months. Eighteen patients underwent a repeat AF/AFL ablation after PVI + diffuse PWI, and 16 (88.9%) patients had durable PVI, in contrast to 10 of 45 (23.9%) patients who had redo ablation after LF-MPSD PVI alone. Seven patients (38.9%) had durable PWI, while 11 patients had partial electrical recovery at the posterior wall. The median percentage of area without electrical activity at the posterior wall was 70.7%. Conduction block across the posterior wall was maintained in 16 (88.9%) patients. CONCLUSION: There was a high rate of PVI durability in patients undergoing diffuse PWI and PVI. Partial posterior wall electrical recovery was common but conduction block across the posterior wall was maintained in most patients.

Prevalence and predictors of pacing-induced cardiomyopathy in young adult patients (<60 years) with pacemakers.

INTRODUCTION: Clinical trials and observational studies of pacing-induced cardiomyopathy (PICM) have largely included elderly patients with mean age >70 years. The prevalence and predictors of PICM in younger patients (age < 60 years) after pacemaker implantation are not known. METHODS: Adults (18-59 years) who received single-chamber ventricular or dual-chamber pacemakers at Vanderbilt University Medical Center from 1986 to 2015 were included. Patients without documented ventricular pacing burden and patients with baseline left ventricular ejection fraction (LVEF) <35% were excluded. PICM was defined as LVEF decrease of ≥ 10% and LVEF < 50% during follow-up with right ventricular pacing ≥20%, and without alternative explanations for cardiomyopathy. RESULTS: A total of 325 patients were included in the study. During a median follow-up duration of 11.5 (Interquartile range 7-17) years, 38 patients (11.7%) developed PICM (1.3 per 100 patient-year). Older age (HR 2.5 for age ≥50 years, p = .013), reduced baseline LVEF (HR 2.4, p = .022), and preimplant AVB (HR 2.7, p = .007) were associated with an increased risk of PICM in the multivariate analysis. Furthermore, baseline AF conferred an increased risk of PICM only in patients without preimplant AVB but not patients with pre-implant AVB. CONCLUSIONS: The incidence of PICM in young patients was low, but PICM could occur more than a decade after pacemaker implantation. Older age, baseline reduced LVEF, and preimplant AVB were associated with an increased risk of PICM in the young patient cohort.

Focal arrhythmia ablation with multipolar mapping: Does it still make sense to stay off-grid?

Multipolar mapping (MPM) has primarily been studied in complex arrhythmia substrates or reentrant circuits. Chieng et al. use a case-control design to compare MPM and point-by-point mapping with an ablation catheter for focal atrial and ventricular tachycardias, showing reduced procedure times and earlier electrograms in the MPM group but no difference in clinical outcomes. It is plausible that faster mapping and better delineation of earliest signals may translate to improved clinical outcomes if studied in a randomized trial in a larger population. Future MPM systems will guide the operator toward the focus in real-time and may even triangulate the source in three dimensions, giving an estimate of depth within the myocardium or likely focus in the opposite chamber.

Premature battery depletion due to compromised low-voltage capacitor in a family of defibrillators.

BACKGROUND: Boston Scientific (Marlborough, MA, USA) implantable cardioverter-defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds) manufactured between 2008 and 2014 are potentially subject to premature battery depletion through a low-voltage capacitor malfunction occurring as a result of hydrogen buildup within the device. Although some of these devices are currently under advisory, other devices manufactured during this timeframe carry a lower risk of the same malfunction. These same devices are known to have superior longevity in general, and the overall mean lifespan of the devices remains long. METHODS: All patients implanted or followed at our two centers who experienced premature battery depletion and had a Boston Scientific ICD or CRT-D potentially at risk for low-voltage capacitor malfunction were studied retrospectively. RESULTS: Nineteen out of 838 patients (2.3%) with devices potentially at risk have had premature battery depletion: 5.7% of those under advisory and 1.1% of those not under advisory. None of our patients had compromised therapy, and all had >27 days of projected battery longevity remaining. CONCLUSIONS: Undetected premature battery depletion in this population of ICDs has the potential to expose a patient to an interval of time where the device is unable to provide therapy. However, with enrollment in remote monitoring, regular follow-up, and attention to audible alerts, the risk of therapy loss due to low-voltage state can be effectively mitigated. For these reasons, prophylactic generator replacement is not recommended.

Extraction of looped transvenous pacing leads to reduce tricuspid regurgitation.

Transvenous leads are a known source of iatrogenic tricuspid regurgitation. It is commonly held that extraction of chronic pacing and defibrillator leads will not reduce this, due to the inevitable trauma to the valve associated with the procedure. We demonstrate three cases of clinically significant reductions in tricuspid regurgitation after extraction of leads that were looped across the tricuspid valve.

Sudden Cardiac Death Despite a Functional Cardioverter-Defibrillator: The Case for Early and Aggressive Therapy for Ventricular Tachycardia in Selected Patients.

We present three cases within 11 months at a single institution of sustained VT that fell below the programmed detection rate of the patients' implantable cardioverter-defibrillators (ICDs), two of which continued until converting to an agonal VF that did not meet criteria for detection, and a third case that could not be successfully defibrillated after a prolonged period of VT. These episodes may be under-recognized due to the dependence of device diagnostic storage on programming and the post-mortem effort that is often required to review these events. Some patients, likely those with the most advanced heart failure, may not tolerate sustained ventricular tachycardia (VT) and may even die from ventricular arrhythmias without ever having a rhythm that meets detection criteria in a ventricular fibrillation (VF) zone.

Stroke and Bleeding Risks of Endocardial Ablation for Ventricular Arrhythmias.

BACKGROUND: Risks of radiofrequency catheter ablation for ventricular arrhythmias include emboli and bleeding complications but data on antithrombotic regimens are limited and guidelines do not specify a systematic approach. OBJECTIVES: This study sought to assess embolic and bleeding complications in relation to pre-periprocedure and post-periprocedure antithrombotic regimens. METHODS: Prospective assessment for complications was performed for 663 endocardial radiofrequency catheter ablation procedures in 616 consecutive patients (median age 64 years [Q1-Q3: 54-73 years], 70.3% men, 71.6% with cardiomyopathy, 44.5% with sustained ventricular tachycardia). RESULTS: There were 2 strokes (0.3%; 95% CI: 0.0%-0.8%), 1 transient ischemic attack (0.15%), and 2 pulmonary emboli (0.3%). There were 39 bleeding complications (5.9%) including 11 pericardial effusions (1.7%), and 28 related to vascular access (4.2%). Consistent with the prevalence of coronary artery disease (47.5%), atrial fibrillation (30.0%), and prior stroke (10.6%), preprocedure, 464 patients (70.0%) were taking antithrombotic agents including 220 (33.2%) taking aspirin alone (ASA), and 163 (24.6%) taking warfarin or a direct acting oral anticoagulant (DOAC). Preprocedure non-ASA antiplatelet use (OR: 2.846; P = 0.011) and DOAC use (OR: 2.585; P = 0.032) were associated with risk of bleeding complications. Following ablation, 49.8% of patients were treated with ASA 325 mg/d and 30.3% received DOACs or warfarin. New DOAC or warfarin administration was initiated in only 6.6% of patients. Overall, 39.7% of patients continued the same preprocedure antithrombotic regimen. CONCLUSIONS: Stroke is a rare complication of radiofrequency catheter ablation for ventricular arrhythmia using ASA 325 mg/d as a minimal postprocedure regimen with more potent regimens for selected patients.

Can Intracardiac Echocardiography Reduce Steam Pops During Half-Normal Saline Irrigated Radiofrequency Ablation?

BACKGROUND: Irrigated radiofrequency ablation with half-normal saline can potentially increase lesion size but may increase the risk of steam pops with the risk of emboli or perforation. We hypothesized that pops would be preceded by intracardiac echocardiography (ICE) findings as well as a large impedance fall. METHODS: In 100 consecutive patients undergoing endocardial ventricular arrhythmia radiofrequency ablation with half-normal saline, we attempted to observe the ablation site with ICE. Radiofrequency ablation power was titrated to a 15 to 20 Ohm impedance fall and could be adjusted for tissue whitening and increasing bubble formation on ICE. Steam pops were defined as audible or a sudden explosion of microbubbles on ICE. RESULTS: Of 2190 ablation applications in 100 patients (82% cardiomyopathy, 50% sustained ventricular tachycardia), pops occurred during 43 (2.0%) applications. Sites with pops had greater impedance decreases of 18 [14, 21]% versus 13 [10, 17]% (P<0.001). ICE visualized 1308 (59.7%) radiofrequency sites, and fewer pops occurred when ICE visualized the radiofrequency ablation site (1.4%) compared with without ICE visualization (2.8%; P=0.016). Of the 18 ICE-visible pops, 7 (39%) were silent but recognized as an explosion of bubbles on ICE. With ICE, 89% of pops were preceded by either tissue whitening or a sudden increase in bubbles. In a multivariable model, tissue whitening and a sudden increase in bubbles were associated with steam pops (odds ratio, 7.186; P=0.004, and odds ratio, 29.93; P<0.001, respectively), independent of impedance fall and power. There were no pericardial effusions or embolic events with steam pops. CONCLUSIONS: Steam pops occurred in 2% of half-normal saline radiofrequency applications titrated to an impedance fall and are likely under-recognized without ICE. On ICE, steam pops are usually preceded by tissue whitening or a sudden increase in bubble formation, which can potentially be used to adjust radiofrequency application to help reduce pops.

Recurrence After Atrial Fibrillation Ablation and Investigational Biomarkers of Cardiac Remodeling.

BACKGROUND: Recurrence after atrial fibrillation (AF) ablation remains common. We evaluated the association between recurrence and levels of biomarkers of cardiac remodeling, and their ability to improve recurrence prediction when added to a clinical prediction model. METHODS AND RESULTS: Blood samples collected before de novo catheter ablation were analyzed. Levels of bone morphogenetic protein-10, angiopoietin-2, fibroblast growth factor-23, insulin-like growth factor-binding protein-7, myosin-binding protein C3, growth differentiation factor-15, interleukin-6, N-terminal pro-brain natriuretic peptide, and high-sensitivity troponin T were measured. Recurrence was defined as ≥30 seconds of an atrial arrhythmia 3 to 12 months postablation. Multivariable logistic regression was performed using biomarker levels along with clinical covariates: APPLE score (Age >65 years, Persistent AF, imPaired eGFR [<60 ml/min/1.73m2], LA diameter ≥43 mm, EF <50%; which includes age, left atrial diameter, left ventricular ejection fraction, persistent atrial fibrillation, and estimated glomerular filtration rate), preablation rhythm, sex, height, body mass index, presence of an implanted continuous monitor, year of ablation, and additional linear ablation. A total of 1873 participants were included. A multivariable logistic regression showed an association between recurrence and levels of angiopoietin-2 (odds ratio, 1.08 [95% CI, 1.02-1.15], P=0.007) and interleukin-6 (odds ratio, 1.02 [95% CI, 1.003-1.03]; P=0.02). The area under the receiver operating characteristic curve of a model that only contained clinical predictors was 0.711. The addition of any of the 9 studied biomarkers to the predictive model did not result in a statistically significant improvement in the area under the receiver operating characteristic curve. CONCLUSIONS: Higher angiopoietin-2 and interleukin-6 levels were associated with recurrence after atrial fibrillation ablation in multivariable modeling. However, the addition of biomarkers to a clinical prediction model did not significantly improve recurrence prediction.

In-hospital and one year outcomes with drug-eluting versus bare metal stents in large native coronary arteries: a report from the Evaluation of Drug-Eluting Stents and Ischemic Events registry.

OBJECTIVES: We sought to compare the clinical outcomes after percutaneous coronary revascularization of large coronary arteries using drug-eluting (DES) or bare-metal (BMS) stents. BACKGROUND: In de novo native coronary lesions with reference diameters of 2.5-3.5 mm, DES reduce target lesion revascularization (TLR) with no increase in death or myocardial infarction (MI). The relative efficacy of DES in larger coronary artery lesions is less certain. METHODS: From the prospective Evaluation of Drug-Eluting Stents and Ischemic Events registry, we identified patients undergoing stenting of de novo lesions in native coronary arteries 3.5-5.0 mm in diameter (n = 1,485). In-hospital and 1-year clinical outcomes were compared for BMS (n = 282) and DES (n = 1,203) patients, using propensity stratification to adjust for differences in potential confounding factors. RESULTS: Most patient characteristics were similar for the two groups, but BMS patients were more likely to have been treated in the setting of ST elevation MI, whereas DES patients had more bifurcation lesions, smaller vessels, and longer total stent lengths. In risk-adjusted analyses, the composite endpoint of 1-year death, MI or TLR was similar for BMS and DES (standardized rate: 11.9% vs. 8.5%, P = 0.10). DES was associated with a 62% reduction in the risk of TLR, although the absolute difference in event rates was small (standardized rates 4.6% vs. 1.8%, P = 0.016). CONCLUSIONS: Among relatively unselected patients undergoing PCI of large native coronary arteries, use of DES was associated with a modest reduction in rates of TLR, with a neutral effect on other ischemic endpoints.

Clinical Outcomes in Patients With Bacteremia and Concomitant Left Ventricular Assist Devices and Cardiac Implantable Electronic Devices.

Infection remains a common cause of morbidity and mortality in patients with both left ventricular assist devices (LVADs) and cardiac implanted electronic devices (CIEDs) with limited data describing outcomes in patients who have both devices implanted. We performed a single-center, retrospective, observational cohort study of patients with both a transvenous CIED and LVAD who developed bacteremia. Ninety-one patients were evaluated. Eighty-one patients (89.0%) were treated medically and nine patients (9.9%) underwent surgical management. A multivariable logistic regression showed that blood culture positivity for >72 hours was associated with inpatient death, when controlled for age and management strategy (odds ratio [OR] = 3.73 [95% confidence interval {CI} = 1.34-10.4], p = 0.012). In patients who survived the initial hospitalization, the use of long-term suppressive antibiotics was not associated with the composite outcome of death or infection recurrence within 1 year, when controlled for age and management strategy (OR = 2.31 [95% CI = 0.88-2.62], p = 0.09). A Cox proportional hazards model showed that blood culture positivity for >72 hours was associated with a trend toward increased mortality in the first year, when controlled for age, management strategy, and staphylococcal infection (hazard ratio = 1.72 [95% CI = 0.88-3.37], p = 0.11). Surgical management was associated with a trend toward decreased mortality (hazard ratio = 0.23 [95% CI = 0.05-1.00], p = 0.05).

Pulmonary Vein Myocardial Sleeve Length and its Association With Sex and 4q25/PITX2 Genotype.

BACKGROUND: Experimental evidence suggests genetic variation in 4q25/PITX2 modulates pulmonary vein (PV) myocardial sleeve length. Although PV sleeves are the main target of atrial fibrillation (AF) ablation, little is known about the association between different PV sleeve characteristics with ablation outcomes. OBJECTIVES: This study sought to evaluate the association between clinical and genetic (4q25) risk factors with PV sleeve length in humans, and to evaluate the association between PV sleeve length and recurrence after AF ablation. METHODS: In a prospective, observational study of patients undergoing de novo AF ablation, PV sleeve length was measured using electroanatomic voltage mapping before ablation. The sentinel 4q25 AF susceptibility single nucleotide polymorphism, rs2200733, was genotyped. The primary analysis tested the association between clinical and genetic (4q25) risk factors with PV sleeve length using a multivariable linear regression model. Covariates included age, sex, body mass index, height, and persistent AF. The association between PV sleeve length and atrial arrhythmia recurrence (>30 seconds) was tested using a multivariable Cox proportional hazards model. RESULTS: Between 2014 and 2019, 197 participants were enrolled (median age 63 years [IQR: 55 to 70 years], 133 male [67.5%]). In multivariable modeling, men were found to have PV sleeves 2.94 mm longer than women (95% CI: 0.99-4.90 mm; P < 0.001). Sixty participants (30.5%) had one 4q25 risk allele and 6 (3.1%) had 2 alleles. There was no association between 4q25 genotype and PV sleeve length. Forty-six participants (23.4%) experienced arrhythmia recurrence within 3 to 12 months, but there was no association between recurrence and PV sleeve length. CONCLUSIONS: Common genetic variation at 4q25 was not associated with PV sleeve length and PV sleeve length was not associated with ablation outcomes. Men did have longer PV sleeves than women, but more research is needed to define the potential clinical significance of this observation.

A Mechanistic Clinical Trial Using (R)- Versus (S)-Propafenone to Test RyR2 (Ryanodine Receptor) Inhibition for the Prevention of Atrial Fibrillation Induction.

BACKGROUND: Experimental data suggest ryanodine receptor-mediated intracellular calcium leak is a mechanism for atrial fibrillation (AF), but evidence in humans is still needed. Propafenone is composed of two enantiomers that are equally potent sodium-channel blockers; however, (R)-propafenone is an ryanodine receptor inhibitor whereas (S)-propafenone is not. This study tested the hypothesis that ryanodine receptor inhibition with (R)-propafenone prevents induction of AF compared to (S)-propafenone or placebo in patients referred for AF ablation. METHODS: Participants were randomized 4:4:1 to a one-time intravenous dose of (R)-propafenone, (S)-propafenone, or placebo. The study drug was given at the start of the procedure and an AF induction protocol using rapid atrial pacing was performed before ablation. The primary endpoint was 30 s of AF or atrial flutter. RESULTS: A total of 193 participants were enrolled and 165 (85%) completed the study protocol (median age: 63 years, 58% male, 95% paroxysmal AF). Sustained AF and/or atrial flutter was induced in 60 participants (84.5%) receiving (R)-propafenone, 60 (80.0%) receiving (S)-propafenone group, and 12 (63.2%) receiving placebo. Atrial flutter occurred significantly more often in the (R)-propafenone (N=23, 32.4%) and (S)-propafenone (N=26, 34.7%) groups compared to placebo (N=1, 5.3%, P=0.029). There was no significant difference between (R)-propafenone and (S)-propafenone for the primary outcome of AF and/or atrial flutter induction in univariable (P=0.522) or multivariable analysis (P=0.199, adjusted for age and serum drug level). CONCLUSIONS: There is no difference in AF inducibility between (R)-propafenone and (S)-propafenone at clinically relevant concentrations. These results are confounded by a high rate of inducible atrial flutter due to sodium-channel blockade. REGISTRATION: https://clinicaltrials.gov; Unique Identifier: NCT02710669.

Clinical and radiographic predictors of cardiovascular implantable electronic device lead failure at the time of initial implantation.

OBJECTIVE: To assess the clinical and radiographic factors associated with lead failure by comparing subjects with lead failure within 10 years of implantation with an implant-year-matched group without lead failure. METHODS: A case-control study with 49 subjects who received Cardiac Implantable Electronic Device (CIED) between January 1, 1999 and July 31, 2008 and developed lead failure within 10 years of implantation in a single center. The control group consisted of subjects (n = 54) with normally functioning leads matched one-to-one by implant year. RESULTS: Among the failure group, the meantime from implantation to device lead failure was 4.70 ± 2.94 years. Older age at implantation was associated with a lower likelihood of lead failure (Odds Ratio (OR) = 0.28 (75 vs 42 years old), 95% CI 0.12-0.63, P = .002). A larger smallest loop diameter on the chest radiograph was also associated with a lower likelihood of lead failure (OR = 0.51 (31 vs 14 mm), 95% CI 0.27-0.97, P = .04). CIED type (defibrillator vs pacemaker) and Ottawa scores were not significantly associated with lead failure. Among lead-specific parameters, defibrillation lead vs pace-sense lead was associated with lead failure (OR = 3.91, 95% CI 1.95-7.81, P < .001). CONCLUSIONS: Younger age, defibrillation leads, and small lead loops are associated with lead failure in CIEDs. Techniques to avoid tight loops in the pocket could potentially reduce the risk of lead failure and bear important implications for the implanting physician.