Barbara Petracci

Failure of implantable cardioverter-defibrillator leads: A matter of lead size?

BACKGROUND Small-diameter implantable cardioverter-defibrillator (ICD) Sprint Fidelis and Riata leads have been recalled owing to an increased risk of lead failure, thus arousing the suspicion that lead size might be a critical issue. OBJECTIVE To compare the incidence of failure of small-diameter (≤8 F) and standard-diameter (>8 F) ICD leads implanted in a single center. METHODS From January 2003 to December 2010, 190 Sprint Fidelis, 182 Riata/Riata ST, 99 Optim (Riata Optim/Durata), and 419 standard-diameter leads were implanted in our center. RESULTS During a median follow-up of 33 months, the overall failure rate was 6.3%. Follow-up duration was similar for Sprint Fidelis, Riata, and standard-diameter leads but shorter for the Optim group. The failure rate was significantly higher in Sprint Fidelis leads than in both standard-diameter (4.8%/year vs 0.8%/year; P<.001) and Riata/Riata ST (4.8%/year vs 2.6%/year; P = .03) leads. The incidence of lead failure in Riata/Riata ST leads proved significantly higher than in standard-diameter leads (2.6%/year vs 0.8%/year; P = .001). No cases of lead failure were recorded in the Optim group. On multivariable analyses, small-diameter (hazard ratio [HR] 5.03, 2.53-10.01, P<.001), Sprint Fidelis (HR 6.3, 3.1-13.3, P<.001), or Riata/Riata ST (HR 4.5, 1.9-10.5, P = .001) leads and age<60 years (HR 2.3, 1.3-4.3, P = .005) were found to independently increase the risk of lead failure. CONCLUSIONS Compared with standard-diameter leads, both Sprint Fidelis and Riata/Riata ST small-diameter ICD leads are at an increased risk of failure, although the incidence of events is significantly lower in the Riata than in the Sprint Fidelis group.

Vagal reflexes following an exercise stress test: A simple clinical tool for gene-specific risk stratification in the long QT syndrome

OBJECTIVES The study assessed whether heart rate (HR) reduction following an exercise stress test (ExStrT), an easily quantifiable marker of vagal reflexes, might identify high- and low-risk long QT syndrome (LQTS) type 1 (LQT1) patients. BACKGROUND Identification of LQTS patients more likely to be symptomatic remains elusive. We have previously shown that depressed baroreflex sensitivity, an established marker of reduced vagal reflexes, predicts low probability of symptoms among LQT1. METHODS We studied 169 LQTS genotype-positive patients < 50 years of age who performed an ExStrT with the same protocol, on and off β-blockers including 47 South African LQT1 patients all harboring the KCNQ1-A341V mutation and 122 Italian LQTS patients with impaired (I(Ks)-, 66 LQT1) or normal (I(Ks)+, 50 LQT2 and 6 LQT3) I(Ks) current. RESULTS Despite similar maximal HR and workload, by the first minute after cessation of exercise the symptomatic patients in both I(Ks)- groups had a greater HR reduction compared with the asymptomatic (19 ± 7 beats/min vs. 13 ± 5 beats/min and 27 ± 10 beats/min vs. 20 ± 8 beats/min, both p = 0.009). By contrast, there was no difference between the I(Ks)+ symptomatic and asymptomatic patients (23 ± 9 beats/min vs. 26 ± 9 beats/min, p = 0.47). LQT1 patients in the upper tertile for HR reduction had a higher risk of being symptomatic (odds ratio: 3.28, 95% confidence interval: 1.3 to 8.3, p = 0.012). CONCLUSIONS HR reduction following exercise identifies LQT1 patients at high or low arrhythmic risk, independently of β-blocker therapy, and contributes to risk stratification. Intense exercise training, which potentiates vagal reflexes, should probably be avoided by LQT1 patients.

Longevity of implantable cardioverter-defibrillators for cardiac resynchronization therapy in current clinical practice: an analysis according to influencing factors, device generation, and manufacturer

Aims Device replacement at the time of battery depletion of implantable cardioverter-defibrillators (ICDs) may carry a considerable risk of complications and engenders costs for healthcare systems. Therefore, ICD device longevity is extremely important both from a clinical and economic standpoint. Cardiac resynchronization therapy defibrillators (CRT-D) battery longevity is shorter than ICDs. We determined the rate of replacements for battery depletion and we identified possible determinants of early depletion in a series of patients who had undergone implantation of CRT-D devices. Methods and results We retrieved data on 1726 consecutive CRT-D systems implanted from January 2008 to March 2010 in nine centres. Five years after a successful CRT-D implantation procedure, 46% of devices were replaced due to battery depletion. The time to device replacement for battery depletion differed considerably among currently available CRT-D systems from different manufacturers, with rates of batteries still in service at 5 years ranging from 52 to 88% (log-rank test, P < 0.001). Left ventricular lead output and unipolar pacing configuration were independent determinants of early depletion [hazard ratio (HR): 1.96; 95% 95% confidence interval (CI): 1.57–2.46; P < 0.001 and HR: 1.58, 95% CI: 1.25–2.01; P < 0.001, respectively]. The implantation of a recent-generation device (HR: 0.57; 95% CI: 0.45–0.72; P < 0.001), the battery chemistry and the CRT-D manufacturer (HR: 0.64; 95% CI: 0.47–0.89; P = 0.008) were additional factors associated with replacement for battery depletion. Conclusion The device longevity at 5 years was 54%. High left ventricular lead output and unipolar pacing configuration were associated with early battery depletion, while recent-generation CRT-Ds displayed better longevity. Significant differences emerged among currently available CRT-D systems from different manufacturers.

Positive trend in survival to hospital discharge after out-of-hospital cardiac arrest: a quantitative review of the literature

Background Seven editions of cardiopulmonary resuscitation (CPR) and emergency cardiovascular care guidelines have been published with many changes, in particular, about CPR. Objectives The aim of our study was to evaluate the temporal trend of survival to hospital discharge after out-of-hospital cardiac arrest (OHCA) as a possible effect of guidelines changes. Methods We searched PubMed for observational studies on ‘survival to hospital discharge after OHCA’. Survival to discharge was the primary outcome; prehospital return of spontaneous circulation and survival to hospital admission were our secondary endpoints. All data were analyzed according to the year of inclusion: group 1 before 2000; group 2 between 2000 and 2005; and group 3 after 2005. Mortality rates were compared between groups by means of a group frequency-weighted log-linear model. Results We considered 38 of 201 studies for a total of 156 301 patients. Survival to hospital discharge rate was 5.0% [95% confidence interval (CI) 4.9–5.2) in group 1; 6.1% (95% CI 5.9–6.4) in group 2; and 9.1% (95% CI 8.9–9.4) in group 3 (P < 0.001). A statistically significant decrease in risk of mortality in group 2 vs. group 1 (risk ratio 0.988, 95% CI 0. 985–0.0.992, P < 0.001) and in group 3 vs. group 2 (risk ratio 0.967, 95% CI 0.964–0.971, P < 0.001) was observed. Similar trends were observed for return of spontaneous circulation and survival to hospital admission. Conclusion Survival to hospital discharge after OHCA has significantly improved. Many aspects may influence survival, but surely, the reduction of time and an early and good quality CPR have positively influenced the outcome.

A comprehensive electrocardiographic, molecular, and echocardiographic study of Brugada syndrome: Validation of the 2013 diagnostic criteria

BACKGROUND The debate on the diagnostic value of high intercostal spaces (ICSs) and of the number of diagnostic leads in Brugada syndrome (BrS) has been settled by a recent expert consensus statement. OBJECTIVE To test the validity, and the underlying anatomy, of the new electrocardiographic (ECG) diagnostic criteria using echocardiographic, molecular, and clinical evidence in 1 clinical study population with BrS. METHODS We analyzed 114 patients with BrS and with a spontaneous or drug-induced type 1 ECG pattern recorded in 1 or more right precordial leads in fourth, third, and second ICSs. The right ventricular outflow tract (RVOT) was localized by using echocardiography. All probands were screened on the SCN5A gene. RESULTS The percentage of mutation carriers (MCs) and the event rate were similar regardless of the diagnostic ICS (fourth vs high ICSs: MCs 23% vs 19%; event rate 22% vs 28%) and the number of diagnostic leads (1 vs ≥2: MCs 20% vs 22%; event rate 22% vs 27%). The concordance between RVOT anatomical location and the diagnostic ICSs was 86%. The percentage of the diagnostic ECG pattern recorded was significantly increased by the exploration of the ICSs showing RVOT by echocardiography (echocardiography-guided approach vs conventional approach 100% vs 43%; P < .001). CONCLUSION The high ICSs are not inferior to the standard fourth ICS for the ECG diagnosis of BrS, and the interindividual variability depends on the anatomical location of the RVOT as assessed by using echocardiography. This approach significantly increases diagnostic sensitivity without decreasing specificity and fully supports the recently published new diagnostic criteria.

Left Ventricular Pacing Lead Positioning in the Target Vein of the Coronary Sinus: Description of a Challenging Case

The optimal left ventricular pacing location for cardiac resynchronization therapy should be individualized according to the site of maximal mechanical delay. However, the presence of vein stenosis or kinking in coronary sinus (CS) anatomy could hamper lead implantation in the target vessel. We describe the case of a patient with dilated cardiomyopathy and a dual‐chamber pacemaker referred for upgrading to a biventricular device owing to New York Heart Association III heart failure symptoms. Tissue Doppler analysis before implantation showed that the area of maximum activation delay was located in the posterolateral region of the left ventricle. Insertion of the lead into a posterolateral vein of the CS by means of the standard over‐the‐wire approach was unsuccessful due to the presence of a stenosis at the ostium of the vein. Lead placement in an anterior vein of the CS was unsatisfactory owing to a poor local delay from QRS onset. After balloon vein angioplasty, the pacing lead passed through the stenotic tract at the ostium of the target vein and was successfully positioned in the posterolateral region. Three months after pacemaker implantation, echocardiography showed an important reduction in the indexes of both inter‐ and intraventricular asynchrony and a significant left ventricular reverse remodeling

Pharmacological therapy following catheter ablation of atrial fibrillation.

Catheter ablation has been proven to be an effective treatment for patients with drug-resistant atrial fibrillation. Nevertheless its efficacy is limited to 60–80% of patients in different studies. Whether the use of pharmacological therapy after catheter ablation of atrial fibrillation might increase the procedural success rate is still a matter of debate. There is general agreement that antiarrhythmic drugs (AADs) are useful in the management of arrhythmias occurring in the very early period after catheter ablation (blanking period). On the contrary, limited data are available on the efficacy of AADs over a longer period. Some patients remain free of arrhythmia recurrences by the use of AADs that were ineffective before catheter ablation: whether this latter situation is to be considered a partial success of catheter ablation or a treatment failure, thus demanding a redo procedure, is still an open question. Some studies have also investigated the role of non-AADs [angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, statins and corticosteroids] in preventing atrial fibrillation recurrences after catheter ablation, reporting conflicting results. Whereas there is a general consensus on the use of anticoagulation therapy in the first phase after catheter ablation, no definite data are available on the proper long-term management of anticoagulation therapy after catheter ablation. This review focuses on the still open issue of what is the optimal pharmacological treatment of patients after catheter ablation of atrial fibrillation.

Women with nonischemic cardiomyopathy have a favorable prognosis and a better left ventricular remodeling than men after cardiac resynchronization therapy

Aims Cardiac resynchronization therapy (CRT) is a well established therapy in heart failure patients who are on optimal medical therapy and have reduced left ventricular ejection fraction (LVEF) and wide QRS complexes. Although women and patients with nonischemic cardiomyopathy are under-represented in CRT trials and registries, there is evidence that these two groups of patients can benefit more from CRT. The aim of our analysis was to investigate the impact of female sex on mortality in a population that included a high percentage of patients (61%) with nonischemic cardiomyopathy. Methods We analyzed data on 507 consecutive patients (20% women) who received CRT at two Italian Heart Transplant centers and were followed up for a maximum of 48 months. Results After multivariate adjustment, women showed a trend toward better survival with regard to all-cause mortality [hazard ratio (HR) 0.32, confidence interval (CI) 0.10–1.04; P = 0.059]. However, this benefit was limited to nonischemic patients with regard to all-cause mortality (HR 0.20, CI 0.05–0.87, P = 0.032) and cardiovascular mortality (HR 0.14, CI 0.02–1.05, P = 0.056). Conclusion Female CRT recipients, at mid-term, have a favorable prognosis than male patients and this benefit appears to be more evident in nonischemic patients. Thus, we strongly believe that the apparent under-utilization of CRT in females is an anomaly that should be corrected.

The economic impact of battery longevity in implantable cardioverter-defibrillators for cardiac resynchronization therapy: the hospital and healthcare system perspectives

Abstract Aims Patients receiving cardiac resynchronization therapy defibrillators (CRT-Ds) are likely to undergo one or more device replacements, mainly for battery depletion. We assessed the economic impact of battery depletion on the overall cost of CRT-D treatment from the perspectives of the healthcare system and the hospital. We also compared devices of different generations and from different manufacturers in terms of therapy cost. Methods and results We analysed data on 1792 CRT-Ds implanted in 1399 patients in 9 Italian centres. We calculated the replacement probability and the total therapy cost over 6 years, stratified by device generation and manufacturer. Public tariffs from diagnosis-related groups were used together with device prices and hospitalization costs. Generators were from 3 manufacturers: Boston Scientific (667, 37%), Medtronic (973, 54%), and St Jude Medical (152, 9%). The replacement probability at 6 years was 83 and 68% for earlier- and recent-generation devices, respectively. The need for replacement increased total therapy costs by more than 50% over the initial implantation cost for hospitals and by more than 30% for healthcare system. The improved longevity of recent-generation CRT-Ds reduced the therapy cost by ∼6% in both perspectives. Among recent-generation CRT-Ds, the replacement probability of devices from different manufacturers ranged from 12 to 70%. Consequently, the maximum difference in therapy cost between manufacturers was 40% for hospitals and 19% for the healthcare system. Conclusions Differences in CRT-D longevity strongly affect the overall therapy cost. While the use of recent-generation devices has reduced the cost, significant differences exist among currently available systems.

La sindrome del QT lungo nella morte improvvisa infantile: una malattia diagnosticabile e curabile

Nei paesi occidentali la sindrome della morte improvvisa infantile (SIDS) rappresenta la causa principale di morte nel primo anno di vita. Le ipotesi finora formulate sulla patogenesi della SIDS rimandano ad un quadro di tipo multifattoriale, in cui fattori di rischio diversi cooperano sinergicamente. Tra le possibili cause non cardiache, sono stati indagati diversi aspetti genetici tra i quali quelli legati a fattori immunitari, neuromodulatori ed enzimatici, che risultano tuttavia di difficile definizione sul piano clinico, soprattutto alla luce di possibili interventi terapeutici. Al contrario e possibile svolgere un’azione preventiva in quei potenziali casi SIDS, riconducibili ad aritmie cardiache su base genetica. Tra le canalopatie, la sindrome del QT lungo riveste un ruolo molto importante, essendo responsabile di circa il 10% dei casi SIDS. Un semplice elettrocardiogramma, eseguito nelle prime settimane dopo la nascita, consente di fare diagnosi di sindrome del QT lungo, individuando quindi i neonati a piu alto rischio aritmico per i quali e possibile iniziare una terapia beta-bloccate, efficace nella prevenzione delle aritmie maligne.