Clemens Steinwender

A Leadless Intracardiac Transcatheter Pacing System

BACKGROUND A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead. METHODS In a prospective multicenter study without controls, a transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies. RESULTS The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval [CI], 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001). CONCLUSIONS In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).

Early performance of a miniaturized leadless cardiac pacemaker: the Micra Transcatheter Pacing Study

Aims Permanent cardiac pacing is the only effective treatment for symptomatic bradycardia, but complications associated with conventional transvenous pacing systems are commonly related to the pacing lead and pocket. We describe the early performance of a novel self-contained miniaturized pacemaker. Methods and results Patients having Class I or II indication for VVI pacing underwent implantation of a Micra transcatheter pacing system, from the femoral vein and fixated in the right ventricle using four protractible nitinol tines. Prespecified objectives were >85% freedom from unanticipated serious adverse device events (safety) and <2 V 3-month mean pacing capture threshold at 0.24 ms pulse width (efficacy). Patients were implanted (n = 140) from 23 centres in 11 countries (61% male, age 77.0 ± 10.2 years) for atrioventricular block (66%) or sinus node dysfunction (29%) indications. During mean follow-up of 1.9 ± 1.8 months, the safety endpoint was met with no unanticipated serious adverse device events. Thirty adverse events related to the system or procedure occurred, mostly due to transient dysrhythmias or femoral access complications. One pericardial effusion without tamponade occurred after 18 device deployments. In 60 patients followed to 3 months, mean pacing threshold was 0.51 ± 0.22 V, and no threshold was ≥2 V, meeting the efficacy endpoint (P < 0.001). Average R-wave was 16.1 ± 5.2 mV and impedance was 650.7 ± 130 ohms. Conclusion Early assessment shows the transcatheter pacemaker can safely and effectively be applied. Long-term safety and benefit of the pacemaker will further be evaluated in the trial. Clinical Trial Registration ClinicalTrials.gov ID NCT02004873.

Long-term outcomes in patients with atrioventricular block undergoing septal ventricular lead implantation compared with standard apical pacing

AIMS Left ventricular function may be altered by right ventricular apical pacing. The aims of the study were to compare the long-term course of different parameters of left ventricular dysfunction in patients undergoing implantation of a dual-chamber pacemaker with the ventricular lead in a septal position vs. in a standard apical position. METHODS We randomized 98 patients with atrioventricular block (AV-block) undergoing pacemaker implantation to positioning the ventricular lead in the high or mid septum (n = 53) or in the apex (n = 45) of the right ventricle. N-terminal pro-brain natriuetic peptide (BNP) levels, left ventricular ejection fraction (LVEF), and exercise capacity were analysed 3 days, 3 months, and 18 months after the implantation. The primary endpoints were the changes of these parameters from baseline to 18 months. RESULTS Changes of BNP levels, LVEF, and exercise capacity from baseline to 18 months were statistically not different between septal and apical stimulation. The clinical occurrence or deterioration of overt heart failure was similar in both treatment arms. CONCLUSION With regard to different parameters of congestive heart failure, a septal stimulation site is not superior to conventional apical pacing in unselected patients undergoing pacemaker implantation for AV-block.

Carotid sinus reactions during carotid artery stenting: Predictors, incidence, and influence on clinical outcome

Carotid sinus reactions (CSR), defined as asystole ≥ 3 sec and hypotension (systolic blood pressure ≤ 90 mm Hg), are frequent events during carotid artery stenting (CAS). Factors predisposing a patient to CSR as well as the impact of CSR on periprocedural complications have not yet been investigated in a prospective manner. The relationship between various clinical, morphologic, and procedural variables and the occurrence of CSR was examined among 105 consecutive patients undergoing successful CAS. After predilatation with a compliant balloon, tubular‐slotted stents were used in all patients. No CSR occurred in 63 (60%) patients, whereas CSR developed in 42 (40%) patients. The most common type of CSR was asystole in combination with short‐term hypotension without clinical symptoms. The most important predictor of CSR was bifurcation location of carotid stenosis (bifurcation > ostial > isolated internal carotid artery; P < 0.001). The other independent predictors were presence of contralateral stenosis (P < 0.02), length of stenosis (P < 0.03), and balloon‐to‐artery ratio (P < 0.02). Occurrence of CSR was unrelated to periprocedural cerebral or cardiovascular complications (7.1% vs. 9.5%; NS). We conclude that CSR occurs frequently (40%) during CAS. Bifurcation location of stenosis is the most important predictor of CSR. CSR does not increase the risk of periprocedural complications. Cathet Cardiovasc Intervent 2003;58:516–523.

Risk Score for Peri-Interventional Complications of Carotid Artery Stenting

Background and Purpose— Routinely available independent risk factors for the peri-interventional outcome of patients undergoing elective carotid artery stenting (CAS) are lacking. The rationale of the study was to create a risk score identifying high-risk patients. Methods— We prospectively enrolled 606 consecutive patients assigned to CAS at a secondary care hospital. Various biochemical, clinical, and lesion-related risk factors were prospectively defined. The primary end point reflecting periprocedural complications encompassed minor and major stroke, nonfatal myocardial infarction and all-cause mortality within 30 days. Results— Three percent of patients (n=18) experienced a nonfatal minor (n=13) or major (n=5) stroke. 1.3% of patients (n=8) died from fatal stroke (n=4) or other causes (n=4). No myocardial infarction was observed within 30 days after stenting. Multivariable analysis revealed diabetes mellitus with inadequate glycemic control (HbA1c >7%), age ≥80 years, ulceration of the carotid artery stenosis, and a contralateral stenosis ≥50% as independent risk factors. A risk score formed with these variables showed a superior predictive value (C-statistic=0.73) compared with single risk factors. The presence of 2 or more of these risk factors identified patients with a risk of 11% for a periprocedural complication compared with 2% in patients with a score of 0 or 1. Conclusions— In patients undergoing elective CAS, a risk score based on routinely accessible variables was able to identify patients at high-risk for atherothrombotic events and all-cause death within 30 days after the intervention.

State of the art of leadless pacing

Despite undisputable benefits, conventional pacemaker therapy is associated with specific complications related to the subcutaneous device and the transvenous leads. Recently, two miniaturized leadless pacemakers, Nanostim™ (St. Jude Medical) and Micra™ (Medtronic), which can be completely implanted inside the right ventricle using steerable delivery systems, entered clinical application. The WiCS™-cardiac resynchronisation therapy (CRT) system (wireless cardiac stimulation for CRT, EBR Systems) delivers leadless left ventricular endocardial stimulation for cardiac resynchronization. In addition to obvious cosmetic benefits, leadless pacing systems may have the potential to overcome some complications of conventional pacing. However, acute and long-term complications still remains to be determined, as well as the feasibility of device explantation years after device placement.

Acute Results of Pulmonary Vein Isolation in Patients with Paroxysmal Atrial Fibrillation Using a Single Mesh Catheter

Introduction: Catheter‐based pulmonary vein isolation (PVI) is an established therapy to treat patients with paroxysmal atrial fibrillation. We evaluated the efficacy of a simplified interventional procedure for PVI by using a single mesh catheter for mapping as well as ablation and with guidance of fluoroscopic imaging only.

Cardiac tamponade following pericarditis 18 days after catheter ablation of atrial fibrillation

Sirs: One year ago, a 68-year-old man was treated with pulmonary vein (PV) isolation for paroxysmal AF. Ostial PV isolation was performed by using the High Density Mesh Ablator Catheter (Bard Electrophysiology, Lowell, MA, USA). The deployed Mesh Ablator was positioned at the anatomical PV ostium. Lesions were created with pulsed RF energy from an RF energy generator (Stockert 1000 XP, Biosense Webster Inc., Diamond Bar, CA, USA). Target temperature was set at 58 C with a maximum energy output of 80 W. After each energy delivery time of 300 s, endocardial electrograms from 10 mm distal to the anatomical PV ostium were obtained with the Mesh Ablator Catheter to confirm circumferential PV isolation. With an energy delivery time of 600 s for each PV, isolation of all PVs could be achieved. Due to AF recurrence, re-ablation was performed 12 months after the first procedure. Before re-ablation, electrical reconnection was documented with a decapolar spiral catheter (Reflexion Spiral Variable Radius Catheter, St. Jude Medical, St. Paul, MN, USA). No PV stenosis was found. For re-ablation, we used a threedimensional mapping system (Ensite NavX, Verismo, St. Jude Medical) for navigation based on a fusion with cardiac computer tomography, and an irrigated-tip ablation catheter (Cool Path, St. Jude Medical) for ablation. To achieve better catheter stability, a steerable sheath (Agilis, St. Jude Medical) was used. The ablation setting consisted of a preselected catheter tip temperature of 42 C, a power of 30 W, and a flow rate of 17 mL/min. Adjacent to the oesophagus visualized with contrast medium swallowed immediately before sedation of the patient, the power was reduced to 25 W. The right sided and the left sided PVs were isolated with a single circumferential antral line and additional ablations at the carina between the superior and inferior PVs, respectively (Fig. 1). After completion of the ablation lines, successful PV isolation was confirmed with the spiral catheter for all PVs. The cumulative RF delivery time was 2,860 s, the procedure time was 230 min. The procedure was completed without any complications. The patient was discharged on a betablocker, an ACE-inhibitor, a proton pump inhibitor and phenprocoumon. The patient was readmitted to hospital 14 days after the second AF ablation because of symptoms suggestive of pericarditis. The leading symptoms consisted of fever up to 38.5 C and chest pain, exacerbated by movement and inspiration. The 12-lead ECG showed non-ischemic STelevation in leads I, II, III, aVL, aVF and V2–V6 (Fig. 2) and blood work showed elevated c-reactive protein and erythrocyte sedimentation rate. A CT scan of the chest and echocardiography revealed no abnormalities. Cardiac enzymes remained negative and the patient was therefore treated with anti-inflammatory drugs. On the fourth day of hospitalization, the patient experienced syncope with subsequent severe cardiogenic shock accompanied by dilated jugular veins associated with not detectable blood pressure. Transthoracic echocardiography performed in the ICU showed significant pericardial effusion. At pericardiocentesis, 400 ml of blood could be removed resulting in restoration of normal blood pressure. Laboratory analyses of the removed blood showed a haemoglobin level comparable to peripheral blood with an oxygen saturation of 91% indicating active bleeding from the left atrium. At this point of time, INR was 1.93 and the T. Lambert (&) C. Steinwender F. Leisch R. Hofmann Cardiovascular Division, City Hospital Linz, Krankenhausstrase 9, 4020 Linz, Austria e-mail: Thomas.lambert@akh.linz.at

64-Detector CT Angiography in Renal Artery Stent Evaluation: Prospective Comparison with Selective Catheter Angiography

PURPOSE To prospectively assess the diagnostic accuracy of 64-detector computed tomographic (CT) renal artery (RA) angiography for the evaluation of RA in-stent restenosis (ISR) by using selective catheter RA angiography as the reference standard. MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. Eighty-six patients (46 men, 40 women; mean age +/- standard deviation, 71 years +/- 9) with 95 RA stents were examined with 64-detector CT RA angiography by experienced radiologists 1 day before selective catheter RA angiography was performed by experienced cardiologists. Each group was blinded to the results of the other imaging method. For image reconstruction, a standard (B25f) and an edge-enhancing (B46f) kernel were chosen. An ISR of more than 50% was considered as hemodynamically significant. Sensitivity, specificity, and positive and negative predictive values for the detection of ISR by using CT RA angiography were calculated. RESULTS At CT RA angiography, 93 (98%) of 95 stents were assessable for diagnosis. Two stents could not be evaluated owing to hardening artifacts affected by vessel calcifications. All nine cases of significant ISR seen at selective catheter RA angiography were correctly diagnosed by using CT RA angiography, giving a sensitivity of 100% and a negative predictive value of 100%. One case of nonsignificant ISR seen at selective catheter RA angiography was interpreted as significant by using CT RA angiography, giving a specificity of 99% and a positive predictive value of 90%. In four of 78 patients without ISR seen at selective catheter RA angiography, CT RA angiography showed nonsignificant ISR, giving a specificity of 95% and a positive predictive value of 56%. CONCLUSION Sixty-four-detector CT RA angiography can provide an excellent noninvasive technique to help detect and evaluate ISR within the RA stents used in our study.

One-year follow-up after pulmonary vein isolation using a single mesh catheter in patients with paroxysmal atrial fibrillation.

BACKGROUND Catheter-based pulmonary vein (PV) isolation has emerged as established therapy for patients with paroxysmal atrial fibrillation (AF). OBJECTIVE The purpose of this study was to determine the results at 1-year follow-up after PV isolation was performed using a single novel multipolar catheter for mapping and ablation. METHODS Patients with paroxysmal AF were screened by cardiac computed tomography for anatomic suitability to undergo PV ablation with the Bard HD Mesh Ablator Catheter (MESH). PV isolation with the MESH was performed only in patients who matched the criteria of four clearly separated PVs with an ostial diameter of 15 to 25 mm. RESULTS PV isolation with the MESH was performed in 36 (55%) of 65 screened patients. In all 36 patients, all PVs could be mapped with the MESH. Electrical isolation could be achieved in 135 (96%) of 140 PVs that revealed PV potentials. One-year follow-up was completed for 35 patients; one patient was lost to follow-up. Ten (29%) patients reported to be symptom-free and had no AF during three 48-hour ECGs, whereas 25 (71%) patients suffered from AF recurrences. Reablation performed in 11 patients revealed reconnection of three PVs in 6 patients and four PVs in 5 patients. CONCLUSION The single-catheter approach using the MESH for mapping and ablation was associated with a high AF recurrence rate within the first year despite a high acute success rate. Thus, the minimalist complexity of the procedure must be balanced with the poor clinical success leading to a high number of second procedures.