Andrew Voigt

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.

Predictors of Complications of Endovascular Chronic Lead Extractions from Pacemakers and Defibrillators: A Single‐Operator Experience

Background: National trends in chronic lead extractions from cardiac rhythm management (CRM) devices are on the rise.

Usefulness of Pulmonary Artery Pressure by Echocardiography to Predict Outcome in Patients Receiving Cardiac Resynchronization Therapy Heart Failure

Secondary pulmonary hypertension is a marker of advanced heart failure (HF) that confers a poor prognosis. Consecutive patients from 2004 through 2005 who underwent echocardiographic assessments of systolic pulmonary arterial pressure (SPAP) before the implantation of cardiac resynchronization therapy defibrillators were included. Patients were divided into tertiles according to baseline SPAP. Patients in the lowest (group I, 20 to 29 mm Hg) and highest (group III, 45 to 88 mm Hg) tertiles were compared for the end points or death or transplantation and for HF hospital admission. Two hundred seventy patients were evaluated, of whom 95% were Caucasians and 91% men. The mean age was 66.5 +/- 11.6 years, the mean QRS duration was 155 +/- 30 ms, the mean left ventricular ejection fraction was 22.6 +/- 9.7%, and the mean New York Heart Association functional class was 3.0 +/- 0.4. In a multivariate model, death or transplantation was significantly more likely in group III (hazard ratio 2.62, 95% confidence interval 1.1 to 6.4, p = 0.036), as was HF admission (hazard ratio 6.35, 95% confidence interval 2.6 to 15.8, p <0.001). In patients with follow-up echocardiographic assessments, a reduction in SPAP was a significant predictor of freedom from the combined end point (hazard ratio 0.29, 95% confidence interval 0.12 to 0.76, p = 0.011). In conclusion, elevated baseline SPAP in patients who underwent cardiac resynchronization therapy is an independent predictor of all-cause mortality or transplantation and HF admission. A decrease in SPAP on follow-up echocardiography is an independent positive prognostic marker.

Fluoroscopic Screening of Asymptomatic Patients Implanted With the Recalled Riata Lead Family

Background— The Food and Drug Administration recently issued a class I recall of the St. Jude Medical Riata implantable cardioverter-defibrillator lead presumably because of increased risk of electric failure and mechanical separation via inside-out abrasion. We sought to examine the incidence and time dependence of inside-out abrasion in asymptomatic patients implanted with the Riata lead. Methods and Results— Asymptomatic patients implanted with the Riata lead at our institution were offered voluntary fluoroscopic screening in 3 views. Electric testing of the Riata lead with provocative isometric muscle contraction was performed at the time of fluoroscopic screening. Of the 245 patients undergoing fluoroscopic screening, 53 (21.6%) patients showed clear evidence of lead separation. Of these externalized leads, 0%, 13%, and 26% had a dwell time of <3 years, 3 to 5 years, and >5 years, respectively (P=0.037). Externalized leads had a significantly pronounced decrease in R-wave amplitude (−1.7±2.9 mV versus +0.35±2.5 mV; P<0.001), and more patients with externalized leads had ≥25% decrease in R-wave amplitude from baseline (28.0% versus 8.1%; P=0.018). One patient with externalization exhibited new noise on near-field electrogram. Conclusions— The Riata lead exhibits time-dependent high rates of cable externalization exceeding 20% at >5 years of dwell time. Externalized leads are associated with a more pronounced decrease in R-wave amplitude, which may be an early marker of future electric failure. The use of fluoroscopic and electric screening of asymptomatic patients with the Riata lead remains controversial in the management of patients affected by the recent Food and Drug Administration recall.

Utility of the Wearable Cardioverter-Defibrillator in Patients With Newly Diagnosed Cardiomyopathy: A Decade-Long Single-Center Experience

BACKGROUND The wearable cardioverter-defibrillator (WCD) has emerged as a means of protecting patients with newly diagnosed nonischemic cardiomyopathy (NICM) or ischemic cardiomyopathy (ICM) against sudden cardiac death while awaiting re-evaluation of cardiac function. OBJECTIVES This study sought to characterize the risk of appropriate WCD therapy in newly diagnosed NICM and ICM patients according to cardiomyopathy etiology in an independent study. METHODS Medical records of all patients prescribed a WCD between June 2004 and May 2015 at our institution (n = 639) were analyzed, focusing on 254 patients with newly diagnosed NICM and 271 patients with newly diagnosed ICM. Patients with a prior implantable cardioverter-defibrillator or sustained ventricular arrhythmias were excluded (n = 114). The primary endpoint was appropriate WCD therapy. RESULTS Median WCD wear time was 61 days (interquartile range [IQR]: 25 to 102 days) per patient and 22 h/day (IQR: 17 to 23 h/day). During 56.7 patient-years, 0 NICM patients received an appropriate WCD shock, whereas 3 (1.2%) received an inappropriate shock. During 46.7 patient-years, 6 (2.2%) ICM patients received an appropriate shock; 5 survived the episode, and 4 survived to hospital discharge. All 6 patients with an appropriate shock were male with QRS duration >120 ms. Two (0.7%) ICM patients received an inappropriate shock. CONCLUSIONS In this independent, retrospective study, the risk of appropriate WCD therapies in patients with newly diagnosed NICM was minimal. Routine use of the WCD in this population should be prospectively evaluated. The risk of appropriate therapies in newly diagnosed ICM was comparable to that observed in prior observational studies.

Recent Trends in Utilization of Implantable Cardioverter-Defibrillators in Survivors of Cardiac Arrest in the United States

Background: Cardiac arrest (CA) is a class I indication for implantable defibrillator (ICD) therapy. We studied the trend of ICD utilization in survivors of CA in the US population between 2002 and 2006.

Beta-blocker Utilization and Outcomes in Patients Receiving Cardiac Resynchronization Therapy

Optimal pharmacologic therapy (OPT) is considered a prerequisite to consideration for cardiac resynchronization therapy (CRT).

Measures of left ventricular dyssynchrony and the correlation to clinical and echocardiographic response after cardiac resynchronization therapy.

There is still no standardized measure of left ventricular (LV) dyssynchrony or definition of response in candidates of cardiac resynchronization therapy (CRT). Recipients of CRT underwent echocardiographic assessment of LV dyssynchrony before and immediately after implantation of a CRT device. Patients were followed for 6 months postimplantation. A total of 44 patients (64 +/- 12 years, 30 men, and 26 with ischemic cardiomyopathy) were included in this analysis. There was a significant decrease in both radial (304 +/- 137 vs 121 +/- 85 ms, p <0.001) and longitudinal (143 +/- 104 vs 95 +/- 43 ms, p = 0.02) measures of LV dyssynchrony immediately after CRT. The immediate post-CRT change in radial (r = -0.43, p = 0.015) but not longitudinal (r = -0.09, p = 0.61) LV dyssynchrony correlated with a significant improvement in the physical component of the quality-of-life score 6 months after CRT. Although a higher baseline longitudinal (p = 0.05) or radial (p = 0.025) LV dyssynchrony predicted a >or=1 improvement in New York Heart Association classification of heart failure 6 months after CRT, acute changes in neither radial (p = 0.71) nor longitudinal (p = 0.89) LV dyssynchrony were predictive of any improved echocardiographic outcomes in follow-up. Concordance between clinical and echocardiographic response to CRT was documented in 72% of patients. In conclusion, both longitudinal and radial measures of LV dyssynchrony improve after CRT. The change in longitudinal but not radial measures of LV dyssynchrony correlates with improved physical quality-of-life score in intermediate term follow-up.

Microvolt T-wave alternans during atrial and ventricular pacing

Introduction: Assessment of microvolt T‐wave alternans (MTWA) by the spectral analysis (SA) method requires the heart rate to be stable within a certain range. This can be achieved by ventricular pacing (VP). We compared MTWA during short‐term VP versus atrial pacing (AP).

Incidence and Predictors of Complications During Cryoballoon Pulmonary Vein Isolation for Atrial Fibrillation

Background Cryoballoon pulmonary vein isolation (PVI) has emerged as an alternative to radiofrequency PVI for atrial fibrillation (AF). Data are lacking to define the rates and predictors of complications, particularly phrenic nerve injury (PNI). Methods and Results We evaluated a single‐center prospective registry of 450 consecutive patients undergoing cryoballoon PVI between 2011 and 2015. Patients were 59±10 years old, 26% were women, 58% had hypertension, their mean CHA 2 DS 2 VASc score was 1.7±1.3, 30% had persistent atrial fibrillation, and 92% received a second‐generation 28‐mm balloon. Predefined major complications were persistent PNI, pericardial effusion, deep vein thrombosis, arteriovenous fistula, atrioesophageal fistula, bleeding requiring transfusion, stroke, and death. PNI was categorized as persistent if it persisted after discharge from the laboratory. Logistic regression was performed to identify predictors of complications and specifically PNI. We identified a major complication in 10 (2.2%) patients. In 49 (10.8%) patients, at least transient PNI was observed; only 5 persisted beyond the procedure (1.1%). All cases of PNI resolved eventually, with the longest time to resolution being 48 days. We also describe 2 cases of PNI manifesting after the index hospitalization. Regression analysis identified 23‐mm balloon use (16.3% versus 5.2%, odds ratio 2.94, P=0.011) and increased age (62.8±7.7 versus 58.7±0.12 years, odds ratio 1.058, P=0.014) as independent significant predictors of PNI. There were no significant predictors of major complications. Conclusions In a large contemporary cohort, cryoballoon PVI is associated with low procedural risk, including lower rates of PNI than previously reported. Older age and 23‐mm balloon use were associated with PNI. Our low rate of PNI may reflect more sensitive detection methods, including compound motor action potential monitoring and forced double‐deflation.