An interventional study of Leadless pacemaker implantation and Conventional transvenous pacemaker implantation in Bradycardia, Atrioventricular Block and Heart Failure, sponsored by Karl Landsteiner University of Health Sciences. Not yet recruiting at 1 site in Austria. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Karl Landsteiner University of Health Sciences · Not applicable, Interventional, and Treatment
People with a slow heart rhythm may need a permanent pacemaker. Conventional pacemakers use a device placed under the skin and wires that pass through veins into the heart. Leadless pacemakers are placed directly inside the heart without a chest pocket or these wires. Both approaches can provide pacing, but their effects on heart function and heart-failure-related problems need to be compared.
LEAP-HF will compare an indication-adapted leadless pacemaker strategy with a conventional transvenous pacemaker strategy in 760 adults for whom either approach is clinically appropriate. Participants must have a left ventricular ejection fraction above 40% and must not require a defibrillator, cardiac resynchronization therapy, or chronic atrial pacing. Participants will be assigned by chance, in equal proportions, to the two strategies. The device and pacing mode will be selected according to the participant's clinical indication within the assigned strategy.
The main question is whether the leadless strategy is not unacceptably worse than the conventional strategy for pacing-induced cardiac dysfunction during 12 months of follow-up. This outcome includes a qualifying deterioration in heart pumping function, pacemaker syndrome, heart failure requiring hospitalization, or an upgrade to cardiac resynchronization therapy. The prespecified non-inferiority margin is an absolute difference of 7 percentage points.
Assessments include heart ultrasound, pacemaker checks, an electrocardiogram, a blood test for NT-proBNP, symptom assessment, and questionnaires about health and quality of life. There will be a telephone contact at 6 weeks and in-person visits at 6 and 12 months after implantation. The study will also compare heart function, complications, further procedures, and deaths. Participants and treating teams will know which pacing system was implanted; selected clinical events will be reviewed by an independent committee unaware of the assigned treatment.
LEAP-HF is a prospective, randomized, controlled, open-label, strategy-based non-inferiority trial coordinated by University Hospital St. Pölten, Austria. Multicentre participation is planned, with a total of 3 to 5 Austrian centres. Recruitment is planned over 24 months, with 12 months of follow-up after each participant's implantation.
Participants will be randomized 1:1 through a centralized web-based system with concealed allocation and variable block sizes. Randomization is stratified by centre, baseline rhythm, and baseline left ventricular ejection fraction. Within the assigned strategy, device selection and programming follow an indication-based algorithm. The comparator is conventional right ventricular pacing; conduction system pacing is not a planned treatment in either randomized strategy.
Baseline assessments are performed within 14 days before implantation and before randomization. Procedural and device data are collected at implantation and discharge. A telephone contact is scheduled at 6 weeks. The in-person 6- and 12-month visits have a window of plus or minus 30 days and include clinical assessment, pacemaker interrogation, standardized echocardiography, a 12-lead electrocardiogram, NT-proBNP measurement, and KCCQ-12 and EQ-5D-5L questionnaires.
The primary analysis includes all randomized participants according to their assigned strategy, irrespective of implantation success, crossover, or protocol deviations. The primary treatment contrast is the absolute difference in 12-month cumulative incidence of pacing-induced cardiac dysfunction, leadless minus transvenous. Death before a qualifying event is a competing event. Non-inferiority is established if the upper bound of the two-sided 95% confidence interval is below 7 percentage points. Per-protocol and as-treated analyses are supportive.
After primary non-inferiority is established, key secondary outcomes are tested in a fixed sequence: change in left ventricular ejection fraction, 12-month NT-proBNP adjusted for baseline, and the composite of all-cause death, any heart-failure hospitalization, or urgent pacemaker-related reintervention. The first two tests assess non-inferiority, with margins of -3.5 percentage points and a ratio of adjusted geometric means of 1.5, respectively; the third assesses superiority. Tests after an unsuccessful step are exploratory rather than confirmatory. The statistical analysis plan will be finalized before recruitment, including handling of death and missing assessments and verification of the sample-size assumptions.
Qualifying clinical events are counted through the nominal 12-month anniversary of implantation. Echocardiographic measurements obtained within the scheduled visit window are assigned to the nominal visit. A qualifying event at 6 months remains part of the 12-month composite even if the condition subsequently improves. Safety events are collected from randomization through the final protocol contact.
Echocardiographic examinations are evaluated independently using standardized procedures. Treatment allocation, nominal visit, previous measurements, and clinical outcomes are not disclosed to readers. Complete masking cannot be guaranteed because implanted hardware, or its absence, may be recognizable. Heart-failure hospitalizations and cardiac resynchronization therapy upgrades are adjudicated by an independent committee blinded to treatment allocation using prespecified criteria and redacted source documents.
An embedded prospective screening registry is planned, subject to applicable consent and regulatory requirements, to characterize screened candidates and external validity. Nonrandomized registry participants are not included in the randomized trial's planned enrollment of 760. Study data are captured in REDCap with role-based access and audit trails. Results will be disseminated regardless of their direction.
317 studies on the registry are indexed under Bradycardia; 71 are open to participants now.
This study's planned enrollment of 760 is above the median of 100 across 187 interventional studies indexed under Bradycardia.
Browse Bradycardia studies →Karl Landsteiner University of Health Sciences is the lead sponsor of 13 studies on the registry; 8 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraindication
A reason a treatment, test or procedure should not be given to a particular person, such as an allergy, another illness or a medicine they take.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants receive an indication-adapted leadless pacing strategy. Permanent atrial fibrillation with bradycardia or after atrioventricular junction ablation is treated with leadless VVI/VVIR pacing. In sinus rhythm without a requirement for chronic atrial pacing, an approved atrioventricular-synchronous ventricular pacing algorithm or dual-chamber leadless pacing is used when clinically appropriate. Device selection and programming follow the prespecified study algorithm.
Device: Leadless pacemaker implantation
Participants receive conventional transvenous right ventricular pacing. Permanent atrial fibrillation is treated with VVI/VVIR pacing. In sinus rhythm, DDD/DDDR pacing is used when atrioventricular-synchronous pacing is clinically indicated. VVI/VVIR is permitted only when clinically appropriate under the prespecified indication criteria; absence of an atrial pacing requirement alone is insufficient justification. Conduction system pacing is not a planned treatment. Right ventricular lead position and programming are documented.
Device: Conventional transvenous pacemaker implantation
Implantation and indication-adapted programming of a leadless pacemaker system. The current protocol lists Medtronic Micra VR2, Medtronic Micra AV2, Abbott AVEIR VR, and Abbott AVEIR AR/VR dual-chamber systems. The selected system must be appropriate for the clinical indication and permitted by the applicable approvals and study protocol. Follow-up includes standardized device interrogation and assessment of ventricular pacing burden.
Implantation and indication-adapted programming of a conventional transvenous single- or dual-chamber pacemaker with right ventricular pacing. The current protocol lists systems from Abbott, Biotronik, Boston Scientific, Medtronic, and MicroPort/Sorin. Device type and pacing mode are selected according to the prespecified clinical algorithm. Lead position, electrical parameters, programming, and right ventricular pacing burden are documented. Conduction system pacing is not part of the assigned strategy.
Cumulative incidence of pacing-induced cardiac dysfunction
Participant-level composite of: (1) LVEF decline of at least 10 percentage points to below 50%, RV pacing burden at least 40%, and no alternative cause; (2) new or worsened symptoms compatible with loss of AV synchrony, reduced AV synchrony, and RV pacing burden at least 40% at the last available interrogation; (3) hospitalization primarily for acute decompensated heart failure requiring IV diuretics and/or vasodilators, with RV pacing burden at least 40%; or (4) CRT upgrade for symptomatic heart failure, LVEF below 50%, and RV pacing burden at least 40%. HF admissions and CRT upgrades use the prespecified interrogation rule and blinded adjudication. Each participant is counted once. Death before PICD is a competing event, not a component. An event at 6 months remains an event at 12 months. LVEF=left ventricular ejection fraction; RV=right ventricular; AV=atrioventricular; CRT=cardiac resynchronization therapy; HF=heart failure; PICD=pacing-induced cardiac dysfunction.
Time frame: Up to 12 months after implantation for clinical events; echocardiographic assessments at 6 and 12 months after implantation (each +/-30 days).
Change in left ventricular ejection fraction from baseline to 12 months
Change in left ventricular ejection fraction (LVEF), expressed in percentage points, assessed by standardized independent echocardiographic evaluation. The treatment contrast is leadless minus transvenous. Non-inferiority requires the lower bound of the two-sided 95% confidence interval to exceed -3.5 percentage points. This is the first key secondary test and is confirmatory only after primary non-inferiority has been established. Handling of death and missing assessments will be prespecified in the statistical analysis plan.
Time frame: Baseline (within 14 days before implantation and before randomization) and 12 months after implantation (+/-30 days).
NT-proBNP at 12 months adjusted for baseline NT-proBNP
N-terminal pro-B-type natriuretic peptide (NT-proBNP) at 12 months, analysed on the logarithmic scale with adjustment for baseline NT-proBNP. The treatment contrast is the ratio of adjusted geometric means, leadless divided by transvenous. Non-inferiority requires the upper bound of the two-sided 95% confidence interval to be below 1.5. This is the second key secondary test and is confirmatory only if all preceding tests succeed. Handling of death and missing assessments will be prespecified in the statistical analysis plan.
Time frame: Baseline (within 14 days before implantation and before randomization) and 12 months after implantation (+/-30 days)
Participants with all-cause death, any heart-failure hospitalization, or urgent pacemaker-related reintervention
Number and percentage of participants with at least one of the following: death from any cause, any heart-failure hospitalization, or urgent pacemaker-related reintervention. Each participant is counted once for the composite. Unlike the primary composite, heart-failure hospitalization in this outcome is not restricted by a right ventricular pacing burden threshold. This is the third key secondary test, assessed for superiority at a two-sided significance level of 0.05 only if all preceding tests succeed; otherwise, the comparison is exploratory.
Time frame: From implantation up to 12 months after implantation.
Change in left ventricular ejection fraction from baseline to 6 months
Change in left ventricular ejection fraction, expressed in percentage points, measured by standardized independent echocardiographic evaluation. This analysis is supportive and is not part of the fixed confirmatory testing sequence.
Time frame: Baseline (within 14 days before implantation and before randomization) and 6 months after implantation (+/-30 days).
Change in NT-proBNP from baseline to 6 months
Change in N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration from baseline to 6 months, expressed in pg/mL. This is a supportive biomarker outcome and is not part of the fixed confirmatory testing sequence.
Time frame: Baseline (within 14 days before implantation and before randomization) and 6 months after implantation (+/-30 days).
New York Heart Association functional class
Distribution of participants across New York Heart Association (NYHA) functional classes I to IV at each assessment. Class I indicates no limitation of physical activity; class IV indicates symptoms at rest and inability to undertake physical activity without discomfort. Higher classes indicate greater functional limitation. Results are reported separately at 6 and 12 months.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
All-cause mortality
Number and percentage of participants who die from any cause during follow-up. Mortality is reported separately from the primary pacing-induced cardiac dysfunction outcome.
Time frame: From implantation up to 12 months after implantation.
Participants with pacing-induced cardiomyopathy
Number and percentage of participants with an absolute decline in left ventricular ejection fraction of at least 10 percentage points from baseline to below 50%, documented right ventricular pacing burden of at least 40%, and no alternative explanation such as myocardial infarction, myocarditis, or severe valve deterioration. Echocardiographic assessment is performed independently. A qualifying event detected at 6 months remains an event even if ventricular function subsequently improves.
Time frame: Up to 12 months after implantation, including the 12-month echocardiographic assessment window (+/-30 days); additional assessment at 6 months (+/-30 days).
Participants with heart-failure hospitalization meeting the primary endpoint criteria
Number and percentage of participants hospitalized with a primary diagnosis of acute decompensated heart failure requiring intravenous diuretics and/or vasodilators, with right ventricular pacing burden of at least 40% established according to the prespecified interrogation rule. Events are confirmed by the blinded clinical events committee.
Time frame: From implantation up to 12 months after implantation.
Participants with cardiac resynchronization therapy upgrade meeting the primary endpoint criteria
Number and percentage of participants receiving a cardiac resynchronization therapy system for symptomatic heart failure with left ventricular ejection fraction below 50% and right ventricular pacing burden of at least 40%, established according to the prespecified interrogation rule. Events are confirmed by the blinded clinical events committee. Clinical treatment decisions remain independent of study endpoint classification.
Time frame: From implantation up to 12 months after implantation.
Participants with any heart-failure hospitalization
Number and percentage of participants with at least one heart-failure hospitalization, irrespective of whether the right ventricular pacing burden criterion of the primary endpoint is met. Events are assessed according to the prespecified adjudication criteria.
Time frame: From implantation up to 12 months after implantation.
Participants with urgent pacemaker-related reintervention
Number and percentage of participants undergoing at least one urgent pacemaker-related reintervention, as defined in the prespecified endpoint manual. This is an individual component of the key secondary clinical composite.
Time frame: From implantation up to 12 months after implantation.
Right ventricular pacing capture threshold
Right ventricular pacing capture threshold measured during device interrogation, expressed in volts. The pulse duration at which the threshold is measured is documented. Values are reported separately at 6 and 12 months.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
Right ventricular sensing amplitude
Intrinsic right ventricular sensing amplitude measured during device interrogation, expressed in millivolts. Values are reported separately at 6 and 12 months.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
Right ventricular pacing impedance
Right ventricular pacing impedance measured during device interrogation, expressed in ohms. Values are reported separately at 6 and 12 months.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
Estimated remaining pacemaker battery longevity
Device-reported estimate of remaining battery longevity, expressed in years, obtained during interrogation. This is an estimated remaining lifespan rather than observed time to battery depletion. Values are reported separately at 6 and 12 months and, where applicable, separately for individual implanted leadless units.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
Right ventricular pacing burden
Percentage of ventricular beats paced, obtained from pacemaker interrogation. The device interrogation interval is documented. Values are reported separately at 6 and 12 months.
Time frame: At 6 and 12 months after implantation (each +/-30 days).
Duration of the index pacemaker implantation procedure
Duration of the index pacemaker implantation procedure, expressed in minutes and recorded according to the study procedural data collection rules.
Time frame: Day 0 (during the index pacemaker implantation procedure).
Fluoroscopy time during the index implantation
Total fluoroscopy time during the index pacemaker implantation procedure, expressed in minutes.
Time frame: Day 0 (during the index pacemaker implantation procedure).
Fluoroscopy dose-area product during the index implantation
Total fluoroscopy dose-area product during the index pacemaker implantation procedure, expressed in Gy cm2 after harmonization of the source equipment units.
Time frame: Day 0 (during the index pacemaker implantation procedure).
Contrast medium volume during the index implantation
Total volume of contrast medium administered during the index pacemaker implantation procedure, expressed in mL.
Time frame: Day 0 (during the index pacemaker implantation procedure).
Participants with major procedure- or device-related complications
Number and percentage of participants with at least one major procedure- or device-related complication, including cardiac perforation or tamponade, vascular access complications, pneumothorax, pocket haematoma, or lead dislodgement or failure. Classification follows the prespecified safety definitions. Cumulative results through 6 and 12 months are reported separately.
Time frame: From implantation up to 12 months after implantation, with cumulative assessments at 6 and 12 months.
Participants with device-system infection
Number and percentage of participants with an infection involving the implanted pacemaker system during follow-up, classified according to the prespecified safety definitions.
Time frame: From implantation up to 12 months after implantation.
Participants with device-system revision or reintervention
Number and percentage of participants with at least one device-system revision or reintervention, including lead revision, device retrieval, device upgrade, or another surgical or catheter-based intervention related to device or procedural complications. This outcome includes urgent and nonurgent interventions. Routine noninvasive programming adjustments alone are not counted as reoperations.
Time frame: From implantation up to 12 months after implantation.
Length of the index hospital stay
Duration of the hospital admission during which the index pacemaker implantation is performed, expressed in days from admission to discharge.
Time frame: From admission to discharge from the index hospitalization, an estimated average of 3 days.
Start is estimated for Nov 2027; primary completion for Dec 2029, 25 months later.
Of 47 non-industry interventional studies with no phase under Bradycardia, half reached primary completion within 28 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 59. This study's planned 25 months is below that.
Counting every sponsor, half of 83 studies reached it within 21 months; a quarter within 12 and three quarters within 38.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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Karl Landsteiner University of Health Sciences