Matteo Ziacchi

Phrenic stimulation: a challenge for cardiac resynchronization therapy.

Background—Phrenic stimulation (PS) may hinder left ventricular (LV) pacing. We prospectively observed its prevalence in consecutive patients with cardiac resynchronization therapy (CRT) devices. Methods and Results—In the years 2003 to 2006, 197 patients received a CRT device. PS and LV threshold measurements were carried out at implantation and at 6-month follow-up. LV reverse remodeling was assessed by echocardiography before implantation and at follow-up. LV lead placement was lateral/posterolateral in 86% of patients. Both PS and LV reverse remodeling occurred most frequently at the lateral/posterolateral LV pacing sites (P<0.001). PS was detected in 73 (37%) of patients and was clinically relevant in 41 (22%). The detection of PS at implantation had a poor sensitivity, as it occurred only in left lateral or sitting position in 27 patients. Ten patients (5%) underwent repeated surgery and 4 (2%) had their CRT turned off because of PS. At follow-up, we could manage PS noninvasively in 32 patients with a small PS-LV threshold difference: in 20 by cathode programmability (3 also thanks to automatic management of LV output) and in 12 (without cathode programmability) by programming the LV output as threshold +1 V. Conclusions—PS may seriously hinder CRT. A bipolar LV lead and cathode programmability are mandatory to avoid PS by changing the LV pacing vector at target sites for CRT. LV stability at target sites despite PS should also be pursued by these means. The automatic adjustment of LV pacing output is complementary in patients with a small PS-LV threshold difference.Background— Phrenic stimulation (PS) may hinder left ventricular (LV) pacing. We prospectively observed its prevalence in consecutive patients with cardiac resynchronization therapy (CRT) devices. Methods and Results— In the years 2003 to 2006, 197 patients received a CRT device. PS and LV threshold measurements were carried out at implantation and at 6-month follow-up. LV reverse remodeling was assessed by echocardiography before implantation and at follow-up. LV lead placement was lateral/posterolateral in 86% of patients. Both PS and LV reverse remodeling occurred most frequently at the lateral/posterolateral LV pacing sites ( P <0.001). PS was detected in 73 (37%) of patients and was clinically relevant in 41 (22%). The detection of PS at implantation had a poor sensitivity, as it occurred only in left lateral or sitting position in 27 patients. Ten patients (5%) underwent repeated surgery and 4 (2%) had their CRT turned off because of PS. At follow-up, we could manage PS noninvasively in 32 patients with a small PS-LV threshold difference: in 20 by cathode programmability (3 also thanks to automatic management of LV output) and in 12 (without cathode programmability) by programming the LV output as threshold +1 V. Conclusions— PS may seriously hinder CRT. A bipolar LV lead and cathode programmability are mandatory to avoid PS by changing the LV pacing vector at target sites for CRT. LV stability at target sites despite PS should also be pursued by these means. The automatic adjustment of LV pacing output is complementary in patients with a small PS-LV threshold difference. Received December 14, 2008; accepted June 10, 2009. # CLINICAL PERSPECTIVE {#article-title-2}

Exercise stress echocardiography is superior to rest echocardiography in predicting left ventricular reverse remodelling and functional improvement after cardiac resynchronization therapy

AIMS Cardiac resynchronization therapy (CRT) improves functional capacity and survival in heart failure. However, one-third of patients fail to respond to CRT. Resting left ventricular (LV) dyssynchrony assessed by echocardiography (ECHO) showed discordant results in identifying CRT responders. LV dyssynchrony can totally change during exercise. Aim of this study was to evaluate whether exercise dyssynchrony could select responders to CRT. METHODS AND RESULTS Sixty-four patients scheduled for CRT implantation performed bicycle exercise ECHO in semi-supine position on an exercise tilting table before and 6 months after CRT implantation. Tissue Doppler imaging (TDI) was acquired both at rest and during exercise to detect LV mechanical dyssynchrony. Predictive values for CRT response were 70% for rest TDI and 89% for exercise TDI (P = 0.01). Exercise LV dyssynchrony was the only parameter independently associated with follow-up improvement of rest ejection fraction and LV volume during multivariable analysis (P < 0.001). Functional improvement at 6-min walking test was statistically higher in patients with exercise dyssynchrony (P = 0.005), and not different considering rest dyssynchrony (P = 0.30). CONCLUSION Exercise intraventricular dyssynchrony assessed by exercise TDI ECHO is a strong independent predictor of CRT response. It could be used to select candidates for CRT, thus reducing ineffective implantations of biventricular pacemakers.

Cardiac Resynchronization Therapy: Variations in Echo‐Guided Optimized Atrioventricular and Interventricular Delays During Follow‐Up

Background: Relatively few data are available on long‐term echocardiographic optimization of atrioventricular (AV) and interventricular (VV) delay programming in cardiac resynchronization therapy (CRT). We assessed variations in optimized AV and VV delays during long‐term follow‐up. Methods: Thirty‐seven consecutive heart failure patients received Doppler echocardiographic optimization of AV and VV delay within 48 hours from CRT device implantation, at 6 months and at 12 months (the last for the first enrolled 14 patients). Results: After implantation, median optimized AV delay was 100 ms (range, 45 ms); VV optimization led to simultaneous biventricular activation in 4 patients, left ventricular preactivation in 17 patients and right ventricular preactivation in 16 patients. At 12 months median AV delay decreased to 85 ms (23 ms) (P < 0.05 vs. baseline). With respect to previous assessment, VV delay variations ≥40 ms were observed in 41% of the patients at 6 months and in 57% of the tested patients at 12 months. A nonconcordance (by Kappa test) of optimized VV delays was found between each new assessment and the previous one. VV delay optimization was associated with significant (P < 0.001) increases in aortic velocity time integral both at baseline and during follow‐up. Conclusions: Echocardiographic optimization of AV and VV delay is associated with broad intraindividual variability during follow‐up. A new assessment of optimized VV delays during long‐term follow‐up reveals a nonconcordance with previous values and provides increases in forward stroke volume.

Longevity of implantable cardioverter-defibrillators: implications for clinical practice and health care systems

AIMS Comparative studies on the longevity of implantable cardioverter-defibrillators (ICDs) among different manufacturers have never been reported. Longevity of ICD devices implanted from 1 January 2000 to 31 December 2002 was prospectively investigated according to their type and manufacturer. METHODS AND RESULTS Longevity of single-chamber (SC), double-chamber (DC), and biventricular (CRT-D) ICDs from Medtronic (MDT), Guidant (GDT), and St Jude Medical (SJM) was measured in all the patients who required device replacement. The observation follow-up ended on 31 December 2007; patients who died prematurely or were transplanted before battery exhaustion were excluded from the analysis. Factors associated with longevity (number of delivered shocks, pacing activity) were researched. One hundred and fifty-three patients received an ICD in the abovementioned period. Six underwent heart transplantation, and 23 died before device replacement; 80 had an SC device, 59 had DC device, and 14 had CRT-D device. Longevity of MDT was superior to GDT and SJM, replacement rates being, respectively, 42%, 95.3%, and 97.2%. Only MDT manufacturers and SC type were associated with greater ICD longevity. Longevity had an impact on the cost/month of treatment of replaced ICDs. CONCLUSION Battery longevity is significantly different among manufacturers. ICD cost is strictly dependent on device longevity, whereas device up-front cost is of limited clinical meaning. Appropriate assessment of cost-effectiveness should be based on ICD longevity in the real-life scenario.

Telecardiology and Remote Monitoring of Implanted Electrical Devices: The Potential for Fresh Clinical Care Perspectives

Telecardiology may help confront the growing burden of monitoring the reliability of implantable defibrillators/pacemakers. Herein, we suggest that the evolving capabilities of implanted devices to monitor patients’ status (heart rhythm, fluid overload, right ventricular pressure, oximetry, etc.) may imply a shift from strictly device-centered follow-up to perspectives centered on the patient (and patient-device interactions). Such approaches could provide improvements in health care delivery and clinical outcomes, especially in the field of heart failure. Major professional, policy, and ethical issues will have to be overcome to enable real-world implementation. This challenge may be relevant for the evolution of our health care systems.

Interventricular Delay Interval Optimization in Cardiac Resynchronization Therapy Guided by Echocardiography Versus Guided by Electrocardiographic QRS Interval Width

Present devices for cardiac resynchronization therapy offer the possibility of tailoring the hemodynamic effect of biventricular pacing by optimization of the interventricular delay (VV) beyond atrioventricular (AV)-interval optimization. It was not yet defined whether a QRS width-based strategy may be a helpful tool for echocardiography for device programming. The aim of the study was to investigate the relation between VV-interval optimization guided by echocardiography and guided by QRS interval width. One hundred six patients with a cardiac resynchronization therapy device for > or =3 months were enrolled. All patients underwent echocardiographic AV and VV delay optimization. The AV interval was optimized according to the E wave-A wave (EA) interval and left ventricular filling time. At the optimal AV delay, VV optimization was performed by measuring the aortic velocity time integral at 5 different settings: simultaneous right and left ventricle output, left ventricle pre-excitation (left ventricle + 40 and 80 ms, respectively), and right ventricle pre-excitation (right ventricle + 40 and 80 ms, respectively). A 12-lead electrocardiogram was recorded and QRS duration was measured in the lead with the greatest QRS width. The electrocardiographic (ECG)-optimized VV interval was defined according to the narrowest achievable QRS interval among 5 VV intervals. The echocardiographic-optimized VV interval was left ventricle + 40 ms in 28 patients, left ventricle + 80 ms in 15 patients, simultaneous in 46 patients, right ventricle + 40 ms in 14 patients, and right ventricle + 80 ms in 3 patients. Significant concordance (kappa = 0.69, p <0.001) was found between the echocardiographic- and ECG-optimized VV interval. In conclusion, significant concordance appeared to exist during biventricular pacing between VV programming based on the shortest QRS interval at 12-lead ECG pacing and echocardiographic-guided VV-interval optimization. A combined ECG- and echocardiographic approach could be a less time-consuming solution in performing this operation.

Actual Pacemaker Longevity: The Benefit of Stimulation by Automatic Capture Verification

Background: We evaluated the impact of an algorithm for automatic right ventricular (RV) stimulation compared to fixed‐output pacing (FOP) stimulation on actual pacemaker longevity over a 9‐year follow‐up.

From lead management to implanted patient management: systematic review and meta-analysis of the last 15 years of experience in lead extraction

Percutaneous lead extraction is considered a safe and effective procedure, although published results derive primarily from cohort studies. The authors performed a systematic review and meta-analysis of the last 15 years’ experience in this field, to give an objective evaluation of the efficacy and safety of this procedure. Moreover, the subsequent metaregression analysis enabled the identification of the main factors influencing these results: patient age, presence of leads in situ for more than 1 year, presence of device infection and use of laser sheath. These findings are significant in order to improve our extraction approach, data reporting and future research.

Meta-analysis of randomized controlled trials evaluating left ventricular vs. biventricular pacing in heart failure: effect on all-cause mortality and hospitalizations.

Randomized controlled trials (RCTs) showed that biventricular (BiV) pacing reduces heart failure (HF) hospitalizations and mortality in patients with New York Heart Association (NYHA) class III–IV HF, left ventricular (LV) dysfunction, and wide QRS. We performed a systematic review and meta‐analysis of the RCTs comparing LV‐only vs. biventricular (BiV) pacing in candidates for cardiac resynchronization therapy (CRT).

Clinical implications of left superior vena cava persistence in candidates for pacemaker or cardioverter-defibrillator implantation

Persistence of a left superior vena cava (LSVC) has been reported in 0.3%–0.4% of candidates for pacemaker (PM) or cardioverter-defibrillator (ICD) implantation. The aim of the study was to evaluate the clinical implications of LSVC persistence for proper device performance. We observed the prevalence of LSVC during a 15-year period. A total of 2077 consecutive patients underwent PM implantation over a 15-year period: 7 had persistent LSVCs (0.34%). Among 599 patients undergoing ICD implantation, 4 LSVCs (0.66%) were observed. Overall LSVC persistence was found in 11/2676 (0.41%) patients. The right superior vena cava was absent in 4/11 (36%) patients. The leads were placed from the left subclavian approach in 5/7 PM patients: 2 received an elective right sided approach due to physician preference. All ICD patients had the device placed left pectoral with a single-coil lead: defibrillation therapy was effective in the long term in all but one patient, who required the addition of a subcutaneous array. Left superior vena cava persistence in PM/ICD patients is similar to the general population (0.41% in our study). The left-sided implant may be skill-demanding during lead placement; however, this task can be accomplished in the majority of cases, with a reliable outcome in the short term and appropriate device performance at follow-up.