Inappropriate Therapies in Modern Implantable Cardioverter Defibrillators: A Propensity Score-matched Comparison between Single- and Dual-Chamber Discriminators in Single-Chamber devices THe sINGle lead Study (THINGS Study).

BACKGROUND: In patients with implantable cardioverter-defibrillators (ICDs), inappropriate therapies (ITs) are often caused by supraventricular tachyarrhythmias (SVTs). OBJECTIVE: To estimate the incidence of IT in modern single-lead ICDs. METHODS: The THINGS study enrolled patients with single-lead ICDs with two SVT discrimination modalities: dual-chamber (DC) via an atrial floating dipole or single-chamber (SC) with morphology criterion. All devices were programmed with two-zone therapy: (i) VT zone from 170 beats-per-minute with ≥15 seconds (≥36 beats) detection time and SVT discriminators, (ii) VF zone from 214 beats-per-minute with ≥7 seconds (≥24 beats) detection time. The primary endpoint was the first occurrence of IT, adjudicated by an independent board. RESULTS: A total of 526 patients (median age 66 years, 83% males), 183 (34.8%) with DC and 343 (65.2%) with SC discrimination, were followed for a median of 2.2 years. The incidence rate of IT was 4.2% (95% CI, 2.7%-6.4%) at 1 year and 7.1% (95% CI, 5.0%-9.9%) at 2 years. Younger age (adjusted HR 0.97, 95% CI 0.95-0.99, P=0.013) and history of atrial fibrillation (adjusted HR 2.67, 95% CI 1.30-5.46, P=0.007) were significantly associated with increased IT risk. In a propensity-score matched comparison, DC discrimination showed a trend towards reduced IT rates compared to SC discrimination in the VT zone (1-year incidence 1.8% vs. 3.5%, P=0.105). CONCLUSION: High-rate VF cutoff and prolonged detection times programming resulted in a low IT rate in single-lead ICD patients with modern SVT discriminators. A trend favoring the DC system was observed in the VT zone.

Twenty-year experience of atrial fibrillation ablation: a single-centre cohort study.

AIMS: While several studies in the literature have reported results of catheter ablation of AF, few is known regarding outcome for more than 10 years. METHODS AND RESULTS: The complete population of patients who underwent AF ablation in the years 2002-2021 in the department of cardiology of the hospital of Reggio Emilia has been analysed. The last follow-up was made in the second half of 2022. During this period the technique of ablation remained relatively unchanged as well the physicians performing ablation. Primary endpoint was the recurrence of symptomatic AF, defined as AF that caused symptoms that were defined by the patient as able to alter their quality of life. 669 patients underwent catheter ablation and 618 were followed until 2022. Median age of the patients was 58 ± 9 years and 521 (78%) were male. There were 407 (61%) of patients with paroxysmal AF, 167 (25%) with persistent AF and 95 (14%) with long-lasting AF. A total of 838 procedures were performed, with a mean of 1.25 per patient. 163 (26%) patients had 2 procedures and 6 had 3 ablations. Periprocedural complications occurred in 4.8% of procedures. Follow-up data were available for 618 patients (92.4%). The median follow-up duration was 6.6 years (IQR 3.2-10.8). The estimated recurrence rate of symptomatic AF was 26% at 10 years, 54% at 15 years and 82% at 20 years. The recurrence rate was similar in patients who had performed one procedure and in those who had performed 2 or 3 procedures. Progression to permanent AF occurred in 112 patients (18%). The major events that occurred during the follow-up consisted of total mortality in 4.5%, heart failure in 3.1% and TIA/stroke in 2.4%. CONCLUSION: Symptomatic AF tends to recur during long-term follow-up despite one or more procedures. Catheter ablation seems able to reduce the rate of symptomatic recurrences and to delay the time of their occurrence. These findings are consistent with the knowledge that an age-dependent progressive structural atriomiopathy is the basis for the development of AF.

Impact of Systematic Use of Intracardiac Ultrasound during Transseptal Catheterization in the Electrophysiology Laboratory.

AIMS: To explore the impact of the use of intracardiac echocardiography (ICE) in the ablation of supraventricular arrhythmias requiring transseptal catheterization (TSC), whilst analyzing the reduction in periprocedural complications and complications specifically related to TSC. METHODS: A retrospective multicenter study collecting data from consecutive atrial fibrillation (AF) and supraventricular ablation procedures that required TSC was performed in five Italian centers. Based on physician discretion, TSC was performed with or without ICE. Periprocedural complications, separating all complications from complications directly related to TSC, were collected. Independent predictors of periprocedural complications and TSC-related complications were investigated. RESULTS: A total of 2181 TSCs were performed on 1862 patients at five Italian centers from 2006 to 2021, in 76% of cases by AF ablation and in 24% by ablation of other arrhythmias with a circuit in the left atrium. Overall, 1134 (52%) procedures were performed with ICE support and 1047 (48%) without ICE. A total of 67 (3.1%) complications were detected, 19 (1.7%) in the ICE group and 48 (4.6%) in the no ICE group, p < 0.001. A total of 42 (1.5%) complications directly related to TSC: 0.9% in the ICE group and 3.1% in the no ICE group (p < 0.001). The independent predictors of all complications were age (OR 1,02 95% C.I 1.00-1.05; p = 0.036), TSC with the use of ICE (OR 0.27 95% C.I 0.15-0.46; p < 0.001) and AF ablation (OR 2,25 95%C.I 1.05-4.83; p = 0.037). The independent predictors for TSC complications were age (OR 1.03 95% C.I 1.01-1.06; p = 0.013) and TSC with the use of ICE (OR 0.24 95% C.I 0.11-0.49; p < 0.001). CONCLUSIONS: ICE reduced periprocedural and TSC-related complications during electrophysiological procedures for ablation of left atrial arrhythmias.

Outcome of the elective or online radiofrequency ablation of typical atrial flutter.

BACKGROUND: Radiofrequency ablation of the cavotricuspid isthmus is currently the first-choice treatment of typical atrial flutter and usually it is performed electively. The purpose of this study was to see whether performing on-line ablation has similar clinical results compared to the conventional strategy. METHODS: Consecutive patients (465) who underwent ablation of the cavotricuspid isthmus for typical atrial flutter (AFL) at our electrophysiology laboratory in the 2008-2017 decade were studied. We evaluated the acute and long-term clinical outcomes of those who were treated electively (337) compared to those who had online ablation (128), that is within 24 hours of presenting to the Department of Cardiology. In patients treated on an emergency basis, a transesophageal echocardiogram was performed to rule atrial thrombi when needed. RESULTS: No significant intraprocedural difference was observed between the 2 patient groups, with comparable acute electrophysiological success (99% vs. 98%) and serious complications. Even at the subsequent 4-year follow-up, there were no significant differences in the recurrence of typical AFL, onset of atrial fibrillation and other clinical events. CONCLUSIONS: Online ablation of typical atrial flutter performed at the time of the clinical presentation of the arrhythmia, was shown to be comparable in terms of procedural safety and clinical efficacy in the short and long term compared to an elective ablation strategy.

Theophylline in patients with syncope without prodrome, normal heart, and normal electrocardiogram: a propensity-score matched study verified by implantable cardiac monitor.

AIMS: Syncope without prodromes in subjects with normal heart and normal electrocardiogram (ECG) is classified as non-classical neurally mediated syncope and is characterized by low adenosine plasma levels (APLs) and frequent asystolic syncope. We assessed the efficacy of theophylline, a non-selective adenosine receptor antagonist, in preventing syncopal events. METHODS AND RESULTS: Participants received an implantable cardiac monitor, underwent APL measurement, and received oral theophylline at maximum tolerated dose (starting dose 300 mg b.i.d.). They were compared with a historical cohort of untreated patients with implantable cardiac monitor who had the same inclusion criteria and were balanced with the propensity score (PS) method as regard age, sex, lifetime syncopal episodes, APL, and antihypertensive drugs. Primary endpoint was time to first syncopal recurrence at 24 months. There were 76 patients in the theophylline group and 58 in the control group. Syncope recurred in 25 (33%) patients in the theophylline group and in 27 (47%) patients in the control group, with an estimated 2-year recurrence rate of 33% and 60%, respectively, and a hazard ratio of 0.53 [95% confidence interval (CI), 0.30-0.95; P = 0.034]. Most of the benefit of theophylline is derived from reduction of syncope due to asystolic atrioventricular (AV) block (hazard ratio of 0.13; 95% CI, 0.03-0.58; P = 0.008). Thirty (39%) patients discontinued theophylline after a median of 6.4 (interquartile range 1.7-13.8) months due to side effects. CONCLUSION: Theophylline was effective in preventing recurrences in patients with syncope without prodromes, normal heart, and normal ECG. The benefit was greater in patients with syncope due to asystolic AV block. CLINICALTRIALS.GOV IDENTIFIER: NCT03803215.

The role of atrial sensing for new-onset atrial arrhythmias diagnosis and management in single-chamber implantable cardioverter-defibrillator recipients: Results from the THINGS registry.

INTRODUCTION: Atrial tachycardia/fibrillation (AT/AF) episodes are common in implantable cardioverter-defibrillator (ICD) recipients and can be undetected by standard single-chamber devices. This study aims to explore whether a single-lead ICD with an atrial dipole (ICD DX; BIOTRONIK SE & Co, Berlin, Germany) could improve the AT/AF diagnosis and management as compared to standard ICD (ICD VR). METHODS AND RESULTS: We selected patients without AT/AF history from the THINGS registry which included consecutive patients implanted with ICD for standard indications. The ICD VR and the ICD DX groups included 236 (62.8%) and 140 (37.2%) patients, respectively, and had no significant differences in baseline characteristics. During a median follow-up of 27 months, there were 7 AT/AF diagnoses in the ICD VR and 18 in the ICD DX group. The 2-year incidence of AT/AF diagnosis was 3.6% (95% confidence interval [CI]: 1.6%-9.6%) for the ICD VR and 11.4% (95% CI: 6.8%-18.9%) for the ICD DX group (adjusted hazard ratio [HR]: 3.85 [95% CI: 1.58-9.41]; P = .003). Initiation of oral anticoagulation (OAC) due to AT/AF diagnosis was reported in 15 patients. The 2-year incidence of OAC onset was 3.6% (95% CI: 1.6%-7.8%) for the ICD VR and 6.3% (95% CI: 3.0%-12.7%) for ICD DX group (adjusted HR: 1.99 [95% CI: 0.72-5.56]; P = .184). CONCLUSION: We observed that atrial sensing capability in single-chamber ICD patients without evidence of atrial arrhythmias at implant is associated with a greater likelihood of detecting AT/AF episodes. The management of these diagnosed arrhythmias often led to clinical interventions, mainly represented by initiation of OAC therapy.

Efficacy of theophylline in patients with syncope without prodromes with normal heart and normal ECG.

BACKGROUND: Patients affected by syncope without or with very short (≤5 s) prodrome with normal heart and normal ECG have been seen to present low plasma adenosine levels. We investigated whether chronic treatment of these patients with theophylline, a non-selective adenosine receptor antagonist, results in clinical benefit. METHODS: In a consecutive case-series of 16 patients (mean age 47 ±â€¯25 years, 9 females) who had ECG documentation of asystolic syncope, we compared the incidence of syncopal recurrence during a period without and a period with tailored theophylline therapy. RESULTS: During a median of 60 months before ECG documentation of the index episode, the patients had a median of 2 syncopes per year. During the 6 months of the study phase without therapy, the patients had a median of 2.6 syncopes per year, p = 0.63. During the 23 months of the study phase with theophylline, the patients had a median of 0.4 syncopes per year, p = 0.005 vs history and p = 0.005 vs no therapy. In the 13 patients who had an implantable loop recorder during both study phases, the incidence of asystolic episodes > 3 s decreased from 9.6 per year to 1.1 per year, p = 0.0007. During theophylline treatment, syncope recurred in 1/5 (20%) patients who had an idiopathic atrioventricular block as the index event versus 9/11 (81%) patients who had a sinus arrest, p = 0.005. CONCLUSION: Theophylline is effective in reducing syncopal burden in patients with syncope without prodromes with normal heart and normal ECG. Its efficacy is greater in those with idiopathic atrioventricular block.

P-Wave Amplitude and PR Changes in Patients With Inappropriate Sinus Tachycardia: Findings Supportive of a Central Mechanism.

BACKGROUND: The mechanism of inappropriate sinus tachycardia (IST) remains incompletely understood. METHODS AND RESULTS: We prospectively compared 3 patient groups: 11 patients with IST (IST Group), 9 control patients administered isoproterenol (Isuprel Group), and 15 patients with cristae terminalis atrial tachycardia (AT Group). P-wave amplitude in lead II and PR interval were measured at a lower and higher heart rate (HR1 and HR2, respectively). P-wave amplitude increased significantly with the increase in HR in the IST Group (0.16±0.07 mV at HR1=97±12 beats per minute versus 0.21±0.08 mV at HR2=135±21 beats per minute, P=0.001). The average increase in P-wave amplitude in the IST Group was similar to the Isuprel Group (P=0.26). PR interval significantly shortened with the increases in HR in the IST Group (146±15 ms at HR1 versus 128±16 ms at HR2, P<0.001). A similar decrease in the PR interval was noted in the Isuprel Group (P=0.6). In contrast, patients in the atrial tachycardia Group experienced PR lengthening during atrial tachycardia when compared with baseline normal sinus rhythm (153±25 ms at HR1=78±17 beats per minute versus 179±29 ms at HR2=140±28 beats per minute, P<0.01). CONCLUSIONS: We have shown that HR increases in patients with IST were associated with an increase in P-wave amplitude in lead II and PR shortening similar to what is seen in healthy controls following isoproterenol infusion. The increase in P-wave amplitude and absence of PR lengthening in IST support an extrinsic mechanism consistent with a state of sympatho-excitation with cephalic shift in sinus node activation and enhanced atrioventricular nodal conduction.

Appropriate implantable cardioverter-defibrillator interventions in cardiac resynchronization therapy-defibrillator (CRT-D) patients undergoing device replacement: time to downgrade from CRT-D to CRT-pacemaker? Insights from real-world clinical practice in the DECODE CRT-D analysis.

Aim: Ventricular tachycardia (VT)/ventricular fibrillation (VF) occurrence after cardiac resynchronization therapy-defibrillator (CRT-D) replacement is unknown; hence, there is no practical guideline to recommend either CRT-D or CRT-pacemaker at the time of device replacement. We observed the 1-year VT/VF occurrence after CRT-D replacement in a subanalysis of the Detect Long-term Complications after ICD Replacement (DECODE) registry. Methods and results: A total of 332 consecutive patients who had undergone CRT-D replacement from 2013 to 2015 were enrolled in 36 Italian centres. The primary endpoint was the number of patients with any appropriate implantable cardioverter-defibrillator (ICD) interventions during 12-month follow-up. The secondary endpoint comprised death from any cause and appropriate ICD interventions. At replacement, 214 (64.5%) patients had a left ventricular ejection fraction ≤ 35% and 138 (41.6%) patients had a secondary prevention indication for ICD. Seventy (21.1%) patients had no longer indication to ICD therapy. During a median follow-up period of 406.5 (362-533) days, VT/VF requiring therapy delivery occurred in 57 (17%) patients, specifically in 7% of those who no longer had an ICD indication. On multivariate analysis, number of criteria for ICD replacement independently predicted appropriate ICD intervention during follow-up [hazard ratio (HR) = 1.62, 95% confidence interval (CI) 1.07-2.46; log-rank P = 0.02]. The combined endpoint of death from any cause or appropriate ICD therapy occurred in 76 (23%) patients. Only NYHA class remained associated with this combined endpoint (HR = 1.97, 95% CI 1.23-3.14; P = 0.005). Conclusions: The DECODE registry showed the 'real-world' experience of CRT-D recipients approaching device replacement, in which 7% of patients who no longer had an indication for ICD therapy experienced appropriate ICD interventions.

Mechanism of syncope without prodromes with normal heart and normal electrocardiogram.

BACKGROUND: "Unexplained syncope, no prodromes, and normal heart" has been described as a distinct clinical and biological entity. OBJECTIVE: The purpose of this study was to assess the mechanism of syncope. METHODS: In this prospective multicenter study, 58 patients presenting with unexplained syncope, no prodromes, and a normal heart received an implantable loop recorder (ILR) and were followed up until a diagnosis was established. Their outcomes were compared with those of 389 patients affected by reflex syncope with prodromes who received an ILR. RESULTS: During a mean observation period of 16 ± 13 months, a diagnostic event was documented by the ILR in 29 patients (50%); an asystolic pause of 11 ± 5 seconds (range 3.5-22 seconds) was present at the time of the diagnostic event in 19 patients (66%). Compared with patients affected by reflex syncope with prodromes, patients with unexplained syncope, no prodromes, and a normal heart more frequently had an asystolic syncope (66% vs 47%; P = .001), and this was more frequently due to idiopathic paroxysmal atrioventricular block (47% vs 21%; P = .04). Ten patients with asystolic pauses underwent cardiac pacing, and 8 patients underwent oral theophylline treatment. During the subsequent 17 ± 12 months of follow-up, syncope recurred in 1 patient on theophylline and presyncope occurred in 1 patient with pacemaker. CONCLUSION: A long asystolic pause, frequently due to idiopathic paroxysmal atrioventricular block, played a role in the mechanism of syncope in two-thirds of patients who had electrocardiographic documentation of a diagnostic event. When a specific therapy was administered in patients with asystolic syncope, the short outcome was favorable.

Implantation of single lead cardioverter defibrillator with floating atrial sensing dipole in a pregnant patient without using fluoroscopy.

In this case report, we look into the implant procedure of a single-lead ICD with floating atrial sensing dipole in a pregnant woman, without using fluoroscopy. This system benefits the proper positioning of the lead. This is possible thanks to the simultaneous display of both the atrial and ventricular dipoles on the electro-anatomical mapping system. This technique may be taken into consideration for the few rare cases where fluoroscopy is absolutely contraindicated.

Long-Term Results After Single and Multiple Procedures of Ablation of Ventricular Tachycardia.

INTRODUCTION: The aim of this study was to assess long-term results after single and multiple procedures of catheter ablation of ventricular tachycardia (VT). While it is generally accepted that multiple procedures are sometimes necessary in order to achieve long-term clinical success, the literature on this issue displays wide variability. METHODS: We assessed the outcome of 160 consecutive patients who underwent 214 ablation procedures in the period 2008 to May 2015: 93 had overt structural heart disease (SHD) (previous myocardial infarction in 74 cases) and 67 had no SHD. RESULTS: After the first procedure, the 1-year actuarial recurrence rates were 25% in patients with SHD and 5% in those without. However, recurrences increased progressively after the first year, reaching 46% and 35%, respectively, at 5 years. Overall, VT recurred in 35/93 (38%) patients with SHD and 22/67 (33%) patients without. Redo (1 to 4) procedures were performed in 28 (20%) patients with SHD and 18 (27%) patients without. After the last procedure, the 1-year actuarial recurrence rates were 5% in patients with SHD and 7% in those without, and the corresponding rates at 5 years were 23% and 7%. During follow-up, 21 patients died (all in the SHD group): no death was related to VT recurrence. CONCLUSIONS: During long-term follow-up, VT frequently recurs after the first procedure, both in patients with SHD and in those without; multiple procedures are needed in order to increase the success rate.

Automatic management of atrial and ventricular stimulation in a contemporary unselected population of pacemaker recipients: the ESSENTIAL Registry.

AIMS: We investigated the applicability of the Ventricular Capture Control (VCC) and Atrial Capture Control (ACC) algorithms for automatic management of cardiac stimulation featured by Biotronik pacemakers in a broad, unselected population of pacemaker recipients. METHODS AND RESULTS: Ventricular Capture Control and Atrial Capture Control were programmed to work at a maximum adapted output voltage as 4.8 V in consecutive recipients of Biotronik pacemakers. Ambulatory threshold measurements were made 1 and 12 months after pacemaker implant/replacement in all possible pacing/sensing configurations, and were compared with manual measurements. Among 542 patients aged 80 (73-85) years, 382 had a pacemaker implant and 160 a pacemaker replacement. Ventricular Capture Control could work at long term in 97% of patients irrespectively of pacing indication, lead type, and lead service life, performance being superior with discordant pacing/sensing configurations. Atrial Capture Control could work in 93% of patients at 4.8 V maximum adapted voltage and at any pulse width, regardless of pacing indication, lead type, and service life. At 12-month follow-up, a ventricular threshold increase ≥1.5 V had occurred in 4.4% of patients uneventfully owing to VCC functioning. Projected pacemaker longevity at 1 month was strongly correlated with the 12-month estimate, and exceeded 13 years in >60% of patients. CONCLUSION: These algorithms for automatic management of pacing output ensure patient safety in the event of a huge increase of pacing threshold, while enabling maximization of battery longevity. Their applicability is quite broad in an unselected pacemaker population irrespectively of lead choice and service of life.

Device Longevity in a Contemporary Cohort of ICD/CRT-D Patients Undergoing Device Replacement.

INTRODUCTION: The longevity of defibrillators (ICD) is extremely important from both a clinical and economic perspective. We studied the reasons for device replacement, the longevity of removed ICD, and the existence of possible factors associated with shorter service life. METHODS AND RESULTS: Consecutive patients who underwent ICD replacement from March 2013 to May 2015 in 36 Italian centers were included in this analysis. Data on replaced devices were collected. A total of 953 patients were included in this analysis. In 813 (85%) patients the reason for replacement was battery depletion, while 88 (9%) devices were removed for clinical reasons and the remaining 52 because of system failure (i.e., lead or ICD generator failure or a safety advisory indication). The median service life was 5.9 years (25th-75th percentile, 4.9-6.9) for single- and dual-chamber ICD and 4.9 years (25th-75th percentile, 4.0-5.7) for CRT-D. On multivariate analysis, the factors CRT-D device, SC/DC ICD generator from Biotronik, percentage of ventricular pacing, and the occurrence of a system failure were positively associated with a replacement procedure. By contrast, the device from Boston Scientific was an independent protective factor against replacement. Considerable differences were seen in battery duration in both ICD and CRT-D. Specifically, Biotronik devices showed the shortest longevity among ICD and Boston Scientific showed the longest longevity among CRT-D (log-rank test, P < 0.001 for pairwise comparisons). CONCLUSION: Several factors were associated with shorter service life of ICD devices: CRT-D, occurrence of system failure and percentage of ventricular pacing. Our results confirmed significant differences among manufacturers.

Long-term clinical outcome of patients who failed catheter ablation of atrial fibrillation.

AIMS: Left atrial ablation fails to prevent symptomatic recurrences of atrial fibrillation (AF) in 20-30% of patients up to 3 years of follow-up despite multiple procedures. Data are lacking on the long-term clinical outcome of those patients for whom the decision was taken to renounce performing further ablation procedures. METHODS AND RESULTS: In this multicentre study, 218 (34%) of 631 consecutive patients, who had undergone AF catheter ablation in the years 2001-11 for drug-refractory symptomatic AF, had symptomatic AF recurrences after 1.5 ± 0.6 procedures. Their long-term clinical outcome was assessed in March 2012 (minimum follow-up 1 year). At a mean of 5.1 ± 2.6 years since their last ablation, 82 (38%) patients improved, 103 (47%) remained unchanged and 33 (15%) worsened, but only 17 (8%) had such a severe impairment of their quality of life as to require atrioventricular junction ablation and pacing (#13) or cardiac surgery (#4); 22 (10%) patients had had adverse clinical events (death in five, heart failure in five, stroke and transient ischaemic cerebral attack in four, severe haemorrhage in four, pacemaker or implantable cardioverter-defibrillator implantation in seven) and 98 (45%) patients had developed permanent AF. Compared with patients without permanent AF, fewer patients with permanent AF improved (3% vs. 66%, P = 0.001) and more got worse (28% vs. 5%, P = 0.001). At multivariable logistic regression, single ablation procedure, left atrial diameter, persistent AF and time from the last ablation were independent predictors of permanent AF. CONCLUSION: More than 5 years after a failed AF ablation, a small minority of patients had such an impaired quality of life as to require non-pharmacological interventions. Almost half developed permanent AF, which significantly impaired quality of life. Permanent AF was more common in patients who had left atrial enlargement, history of persistent AF, longer follow-up, and had performed a single ablation procedure, thus hypothesizing that reablation could reduce the chronicization of arrhythmia. A low risk of stroke was observed in the long-term follow-up.

Atrial sensor, remote monitoring and new anticoagulant drugs: Identification and treatment of a patient with unknown and asymptomatic atrial flutter.

This case report describes how new tools and technologies can drive a different approach in the management of arrhythmic patients. An unknown and asymptomatic atrial flutter was detected by the atrial sensor mounted in a single lead implantable cardioverter defibrillator. Moreover daily remote monitoring of the device allowed early notification and prompt clinical reaction. Anticoagulant therapy onset, radiofrequency ablation and the following anticoagulant therapy removal were driven by the device data transmissions.