Left and Right Parasternal Sensing for the S-ICD in Adult Congenital Heart Disease Patients and Normal Controls.

BACKGROUND: This study investigated the impact of a right parasternal sensing electrode position on the R- and T-wave amplitudes and the R:T ratio in three subcutaneous implantable cardioverter defibrillator (S-ICD) vectors in patients with adult congenital heart disease (ACHD) and normal controls. METHODS: Conventional left parasternal sensing electrode position and right parasternal sensing electrode positions were used to collect 10-second electrograms, recorded through an 80-electrode body surface mapping technology (Prime ECG™ system, Heartscape Technologies Inc., now Verathon, Columbia, MD, USA). Recordings were made in the supine, prone, left lateral, right lateral, sitting, and standing positions in using both the standard electrode vector position and the right parasternal positions. RESULTS: Forty patients were recruited and 37 patients were used for analysis. Twenty-seven (73%) had complex ACHD; 10 patients had normal hearts and acted as controls. A total of 3,708 data points were analyzed. There were no significant differences in the R:T ratio when measured in ACHD patients in the right compared to the left parasternal lead position. In contrast, there were important differences in the magnitude of the R:T ratio when measured in control patients in the right compared to the left parasternal lead position; in the primary vector, the R:T ratio was greater in right than left by 2.99 (P = 0.0002; 95% confidence interval [CI]: 1.48-4.50) and in the secondary vector, the R:T ratio was smaller in the right than in the left by 0.77 (P = 0.004; 95% CI: -1.58-0.05). CONCLUSION: In selected patients, a right parasternal lead position may provide a useful alternative sensing configuration for the S-ICD.

Potential eligibility of congenital heart disease patients for subcutaneous implantable cardioverter-defibrillator based on surface electrocardiogram mapping.

AIMS: The eligibility of complex congenital heart disease (C-CHD) patients for subcutaneous implantable cardioverter-defibrillator (S-ICD) has yet to be determined. The aim of this study was to determine in C-CHD patients: (i) the S-ICD eligibility, (ii) the most effective sensing vector, (iii) the impact of posture change on screening eligibility, and (iv) the impact of using two vs. six postures for screening. Adults with structurally normal hearts were used as controls. METHODS AND RESULTS: The Boston Scientific ECG screening tool was used to determine eligibility for S-ICD in two and six different postures in 30 patients with C-CHD and 10 controls. Statistical significance was determined using Fisher's exact test. In total, 1440 bipolar vectors were collected. The mean age was 36.3 years, 57% subjects were men. Over all 86.7% of C-CHD patients and 100% controls (P > 0.05) met S-ICD eligibility. In controls, the primary vector (PV) was the most effective, and the alternate vector (AV) was least effective. In C-CHD patients, the AV was comparable to the PV. Posture change did not significantly affect S-ICD eligibility in C-CHD patients and controls (P > 0.05). Screening with six postures vs. two did not significantly affect S-ICD eligibility of C-CHD patients (83% vs. 87%, P > 0.05) or controls (90% vs. 100% P = >0.05). CONCLUSION: No significant differences were observed between S-ICD eligibility in C-CHD patients and controls. The AV and PV are most suitable in C-CHD patients. No significant impact of postural change was observed for S-ICD eligibility between the two groups. No significant difference was observed in S-ICD eligibility when screening using two or six postures in both groups.

Detection of transient regional myocardial ischemia using body surface Delta map in patients referred for myocardial perfusion imaging--a pilot study.

BACKGROUND: The diagnosis of transient regional myocardial ischemia (TRMI) in patients presenting with stable chest pain is a challenge. Exercise Tolerance Test (ETT) is no longer recommended in most cases due to its flaws. Alternative tests are more expensive and less readily available. The BSM Delta map is an intuitive color display of digitally subtracted ST-segment shift derived from two 80-electrode BSM recordings at baseline and at peak stress, and has shown promise as a tool for detection of TRMI. OBJECTIVES: The purpose of this pilot study was to assess the feasibility of BSM Delta map as a tool to detect TRMI using dobutamine stress ECG gated single-photon emission computed tomography myocardial perfusion imaging (MPI) as a reference. METHOD: Forty consecutive patients were recruited who were referred for MPI with a history of angina-like symptoms. The BSM Delta map was derived from two 80-electrode body surface mapping system recordings carried out simultaneously with MPI at (a) baseline and (b) peak dobutamine stress. Standard 12-lead ECGs were also recorded at the same time points. RESULTS: The mean patient age was 68±7.1years, and 52% (21/40) were female. Using MPI as the reference the sensitivity of BSM Delta map was 82% (9/11) and specificity was 86% (25/29) (95% CI 0.688-0.992), positive likelihood ratio 5.93 (95% CI 2.29-15), negative likelihood ratio 0.21 (95% CI 0.06-0.75). The sensitive of the 12-lead ECG was 36% (4/11) and specificity was 76% (22/29) (95% CI 0.356-0.767), positive likelihood ratio 1.51 (95% CI 0.55-4.15), negative likelihood ratio 0.84 (95% CI 0.51-1.37). BSM Delta map is more sensitive and specific (McNemar's chi-square test p=0.03 (95% CI, 0.448-0.924). The PPV and NPV for BSM Delta map were 69% (9/13) and 93% (25/27) respectively, compared with 36% (4/11) and 76% (22/29) for 12-lead ECG. CONCLUSION: This pilot study confirms the feasibility of using Delta map in this context and suggests that it has promising diagnostic accuracy and is superior to the 12-lead ECG. It could potentially represent a clinically suitable screening tool for TRMI in patients presenting with stable chest pain, since it is near patient and requires little specialist training for acquisition and interpretation. A larger clinical study is now required.

Rates of upgrade of ICD recipients to CRT in clinical practice and the potential impact of the more liberal use of CRT at initial implant.

BACKGROUND: Many implantable cardioverter defibrillator (ICD) recipients may develop indications for cardiac resynchronization therapy (CRT) during follow-up. However, the actual upgrade rate during follow-up in clinical practice is not known. METHODS: We performed a single center retrospective observational study of all new ICD implants over 5 years (2003-2007). The rate of CRT upgrade of patients initially implanted with a single-/dual-chamber ICD during follow-up was assessed. The impact of using alternative criteria on the need for CRT in ICD recipients at initial implant was also evaluated. RESULTS: During the study period, there were 549 new ICD implants. The initial implant was a single/dual-chamber ICD in 73% (n = 399) and a CRT-D in 27% (n = 150). During follow-up (48±20 months) of the 399 ICD recipients, 70 (17.5%) died and 15 (3.8%) were upgraded to CRT, including eight cases where left ventricular lead implant had been initially unsuccessful. Upgrade rates at 1, 3, and 5 years were 0.03%, 2.4%, and 5.1%, respectively. Using alternative CRT criteria (left ventricular ejection fraction [LVEF]≤30%, QRS ≥130 ms, New York Heart Association I-IV) 42.6% (n = 234) of ICD recipients met criteria for CRT at initial implant. CONCLUSION: In this retrospective single center study, rates of CRT upgrade in ICD recipients over the medium term were low, which may reflect underuse in otherwise appropriate candidates. The more liberal use of CRT at initial implant in patients with a reduced LVEF, a broad QRS, but only mild heart failure symptoms would require approximately 50% increase in CRT use in ICD recipients at initial implant, and may help address some of the suggested underutilization.

Defining potential to benefit from implantable cardioverter defibrillator therapy: the role of biomarkers.

AIMS: Implantable cardioverter defibrillator (ICD) therapy improves survival in patients at high sudden cardiac death (SCD) risk. However, some patient groups fulfilling indications for ICD therapy may not gain significant benefit: patients whose absolute risk of SCD is low and patients whose risk of death even with an ICD is high. The value of biomarkers in identifying patients' potential for survival benefit from ICD therapy is unknown. We performed a pilot study to investigate this. METHODS AND RESULTS: Five established cardiovascular biomarkers were measured in patients with ICDs on the background of left ventricular dysfunction: N-terminal pro-brain natriuretic peptide [NT-proBNP], soluble ST2 [sST2], growth differentiation factor-15, C-reactive protein, and interleukin-6. The endpoints were all-cause mortality and survival with appropriate ICD therapy. One hundred and fifty-six patients were enrolled (age 69 years [Q1-Q3 62-77], 85% male, 76% ischaemic aetiology). During a follow-up of 15 ± 3 months, 12 patients died and 43 survived with appropriate ICD therapy. In a Cox proportional hazards model, the strongest predictors of death were Log sST2 (P< 0.001), serum creatinine (P< 0.001), and Log NT-proBNP (P= 0.002). The strongest predictor of survival with appropriate ICD therapy was Log NT-proBNP (P= 0.01). CONCLUSION: The biomarkers NT-proBNP and sST2 are promising biomarkers for identifying patients with little potential to gain significant survival benefit from ICD therapy. However, their incremental benefit, in addition to currently available clinical risk prediction models, remains unclear. These results demand a confirmatory prospective cohort study, designed and powered to derive and validate prediction algorithms incorporating these markers.

Transseptal left ventricular endocardial pacing reduces dispersion of ventricular repolarization.

BACKGROUND: Cardiac resynchronization therapy (CRT) may be proarrhythmic in some patients. This may be due to the effect of left ventricular (LV) epicardial pacing on ventricular repolarization. The purpose of this study was to evaluate the effect of endocardial versus epicardial LV biventricular pacing on surface electrocardiogram (ECG) parameters that are known markers of arrhythmogenic repolarization. METHODS: ECG markers of repolarization (QT dispersion, QTD; T peak to end, T(peak-end) ; T(peak-end) dispersion, T(peak-end) D; QTc) were retrospectively measured before and after CRT in seven patients with transseptal LV endocardial leads (TS group), 28 matched patients with coronary sinus (CS) LV leads (CS group), and eight patients with surgical LV epicardial leads (SUR group). All ECGs were scanned and analyzed using digital callipers. RESULTS: Compared to the CS group, the TS group CRT was associated with a significant postpacing reduction in QTD (-45.2 ± 35.6 vs -4.3 ± 43.6 ms, P = 0.03) and T(peak-end) (-24.2 ± 22.1 vs 3.4 ± 26.7 ms, P = 0.02). There was a nonsignificant post-CRT reduction in both T(peak-end) D (-11.3 ± 31.0 vs 2.4 ± 28.9 ms, P = 0.27) and QTc (-50.0 ± 46.4 vs 4.4 ± 70.2 ms, P = 0.06) in the TS versus the CS group. In contrast, there were no differences between the SUR and CS groups in terms of the effect of CRT on these repolarization parameters. CONCLUSIONS: CRT with (atrial transseptal) endocardial LV lead placement is associated with repolarization characteristics that are considered to be less arrhythmogenic than those generated by CS (epicardial) LV lead placement. Further work is needed to determine whether these changes translate to a reduction in proarrhythmia.

Takotsubo cardiomyopathy: a diagnostic challenge.

The frequency of the diagnosis of takotsubo cardiomyopathy has increased rapidly over the past few years, possibly due to increasing awareness among cardiologists. At initial presentation the diagnosis remains a challenge because of the close similarity between the presentation of takotsubo cardiomyopathy, and that of ST elevation myocardial infarction (STEMI). Recognition of salient aspects of the medical history at presentation are important in order to organise further appropriate investigations such as echocardiography and left ventriculography at the time of coronary angiogram. Takotsubo cardiomyopathy can be easily missed without ventriculography early after presentation because of the transient nature of left ventricular dysfunction, and in many centres left ventriculogram is not done as standard in the setting of STEMI. The authors advocate left ventriculography in all cases of ST elevation who have unobstructed coronaries. The correct diagnosis of takotsubo cardiomyopathy is very important for future advice and management of the patient. The prognosis of this condition is generally excellent with almost all patients returning to normal within a few weeks. This article examines the takotsubo cardiomyopathy literature and discusses the pathophysiology, clinical features, management, and prognosis of this condition in the context of an illustrated case.

Is the use of an additional pace/sense lead the optimal strategy for the avoidance of lead extraction in defibrillation lead failure? A single-centre experience.

AIMS: The implantation of an additional pace-sense (P/S) lead is a standard treatment option in the management of an isolated pace-sense problem in a defibrillation (HV-P/S) lead. However, the safety of this management strategy is unclear. We performed a retrospective single-centre study to assess this. METHODS AND RESULTS: We studied all patients with an isolated P/S problem in an HV-P/S lead, treated with an additional P/S lead, in our institution. The need for further invasive intervention for a lead-related complication, or death during follow-up, was assessed. From 2000 to 2008, 45 patients were treated with an additional P/S lead. Mean follow-up was 78 +/- 38 months from original device implantation and 28 +/- 17 months following implantation of the additional lead. During follow-up, three patients required an invasive intervention for a lead-related problem. All were successfully treated with lead extraction and device re-implantation. There were five deaths. Following implant of an additional lead, cumulative survival from further lead defects after 6 months, 1, 2, and 3 years was 100, 100, 93, and 87%, respectively. CONCLUSION: In the treatment of an isolated P/S problem in an HV-P/S lead, the placement of an additional P/S lead is a safe management strategy, at least in the short term.

Sensitivity and specificity of the subcutaneous implantable cardioverter defibrillator pre-implant screening tool.

BACKGROUND: The sensitivity and specificity of the subcutaneous implantable cardioverter defibrillator (S-ICD) pre-implant screening tool required clinical evaluation. METHODS: Bipolar vectors were derived from electrodes positioned at locations similar to those employed for S-ICD sensing and pre-implant screening electrodes, and recordings collected through 80-electrode PRIME®-ECGs, in six different postures, from 40 subjects (10 healthy controls, and 30 patients with complex congenital heart disease (CCHD); 10 with Tetralogy of Fallot (TOF), 10 with single ventricle physiology (SVP), and 10 with transposition of great arteries (TGA)). The resulting vectors were analysed using the S-ICD pre-implant screening tool (Boston Scientific) and processed through the sensing algorithm of S-ICD (Boston Scientific). The data were then evaluated using 2 × 2 contingency tables. Fisher exact and McNemar tests were used for a comparison of the different categories of CCHD, and p < 0.05 vs. controls considered to be statistically significant. RESULTS: 57% of patients were male, mean age of 36.3 years. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the S-ICD screening tool were 95%, 79%, 59% and 98%, respectively, for controls, and 84%, 79%, 76% and 86%, respectively, in patients with CCHD (p = 0.0001). CONCLUSION: The S-ICD screening tool was comparatively more sensitive in normal controls but less specific in both CCHD patients and controls; a possible explanation for the reported high incidence of inappropriate S-ICD shocks. Thus, we propose a pre-implant screening device using the S-ICD sensing algorithm to minimise false exclusion and selection, and hence minimise potentially inappropriate shocks.

Detection of regional myocardial ischaemia by a novel 80-electrode body surface Delta map in patients presenting to the emergency department with cardiac-sounding chest pain.

BACKGROUND: Presentation with acute chest pain is common, but the conventional 12-lead ECG has limitations in the detection of regional myocardial ischaemia. The previously described method of the body surface mapping system (BSM) Delta map, derived from an 80-electrode BSM, as well as a novel parameter total ischaemic burden (IB), may offer improved diagnostic sensitivity and specificity in patients with myocardial ischaemia. METHODS: The feasibility of using the novel BSM Delta map technique, and IB, for transient regional myocardial ischaemia was assessed in comparison with 12-lead ECG in 49 patients presenting to the emergency department (ED) with cardiac-sounding chest pain. RESULTS: The sensitivity and specificity of 12-lead ECG for the diagnosis of acute coronary syndrome (ACS) was 67 and 55%, respectively, positive likelihood ratio (+LR) 1.52 [95% confidence interval (CI) 0.86, 2.70] and negative likelihood ratio (-LR) 0.58 [95% CI 0.30, 1.12]. The sensitivity and specificity of the BSM Delta map for the diagnosis of ACS was 71 and 78%, +LR 3.19 [95% CI 1.31, 7.80], -LR 0.37 [95% CI 0.20, 0.68]. There was a significantly positive correlation between peak troponin-I concentration and IB (r=0.437; P<0.002). CONCLUSION: This pilot study confirms the feasibility of using the Delta map for the diagnosis of ACS in patients presenting to the ED with cardiac-sounding chest pain and suggests that it has promising diagnostic accuracy and has superior sensitivity and specificity to the 12-lead ECG. The novel parameter of IB shows a significant correlation with troponin-I and is a promising tool for describing the extent of ischaemia. The use of the BSM Delta map in the ED setting could improve the diagnosis of clinically important ischaemic heart disease and furthermore presents the result in an intuitive manner, requiring little specialist experience. Further larger scale study is now warranted.

Treatment of coronary aneurysms with covered stents: a review with illustrated case.

Coronary aneurysms are found in approximately 5% of patients undergoing coronary angiography. Most coronary artery aneurysms (CAAs) are associated with significant stenosis of the coronary lumen; however, there is no common consensus on the treatment of coronary aneurysms. A large aneurysm in the coronary artery makes the blood flow turbulent and predisposes to thrombus formation and coronary artery obstruction even without the presence of significant stenosis. Despite this important anatomical abnormality of the coronary artery, the treatment options are poorly understood and present a therapeutic challenge to the interventional cardiologist. While treating CAAs with percutaneous implantation of covered stents offers a less invasive option compared to surgical correction, the short- and long-term outcomes are unknown. In this article, we have reviewed the literature and discussed the pathophysiology, clinical importance, and treatment options for CAAs. The illustrated case demonstrates a difficult situation in the management of CAA with interesting images, including coronary angiography, intravascular ultrasound, and transesophageal echocardiography of the complication encountered in this particular case.

Proteomic profiling to identify prognostic biomarkers in heart failure.

BACKGROUND: The ability to predict mode, as well as risk, of death in left ventricular systolic dysfunction (LVSD) is important, as the clinical and cost-effectiveness of implantable cardioverter defibrillators (ICD) therapy depends on its use in appropriately selected patient populations. The value of a proteomic approach in identifying prognostic biomarkers in LVSD is unknown. The aims of this pilot study were to use proteomic techniques to identify serum biomarkers associated with LVSD and to prospectively explore their association with prognosis. PATIENTS AND METHODS: Serum was analysed by surface-enhanced laser desorption ionisation time-of-flight mass spectrometry (SELDI-TOF MS) in patients with (n=78) and without (n=45) systolic heart failure (SHF). Spectra were compared to identify differentially expressed signal peaks as potential biomarker indicators. The ability of these peaks to predict all-cause mortality and survival with appropriate ICD therapy was then tested prospectively in patients with ICDs, on the background of LVSD (n=141). RESULTS: For the identification stage spectra (2-200 kDa) from SHF and control patients were randomly separated into two equally sized discovery and validation sets. Six protein peaks were identified that were differentially expressed in SHF in both sets. In the prospective phase, during a mean follow-up of 15±3 months, 11 patients died and 39 survived with appropriate ICD therapy. Five out of the six proteomic biomarkers predicted all-cause mortality but none predicted appropriate ICD therapy. CONCLUSION: These results provide proof-of-principle and are supportive of the SELDI proteomic approach as a high-throughput screening tool in identifying potentially prognostic protein peaks in patients with LVSD.

Single-center experience of catheter ablation for atrial fibrillation using multi-electrode mapping and ablation catheters.

PURPOSE: Radiofrequency ablation (RFA) is an established therapy for the treatment of paroxysmal and persistent atrial fibrillation (AF). Many techniques have been reported to achieve RFA. We report a single-center experience of RFA using three multi-electrode catheters. METHODS: We collected data of the patients who had RFA for AF using custom-designed multi-electrode mapping and ablation catheters between May 2007 and November 2009 at this center. RESULTS: A total of 105 patients aged 56 ± 9.6 years underwent RFA using three multi-electrode catheters. Eighty-seven patients were new and 18 patients had re-do AF ablation using the multi-electrode mapping and ablation catheters. In the new patients, the mean procedure duration was 141 ± 38 minutes and fluoroscopy time was 38 ± 4 minutes. The mean duration of follow-up was 15.8 ± 6.4 months. Symptomatic improvement was achieved in 75 patients (86%), 48 patients (55%) remained in sinus rhythm (SR) after the first procedure, while 7 (8%) had multiple procedures and remained in SR without antiarrhythmic drugs (AAD). Fourteen patients (16%) required AAD following a single procedure and 1 patient (1.1%) after multiple procedures to remain in SR. Seven patients (8%) had reduced burden of symptoms. No improvement occurred in 12 patients (13.7%). In the 18 re-do patients, 15 (83.3%) had symptom improvement. Four patients (22.2%) remained in SR after a single procedure and 4 patients (22.2%) required multiple procedures to remain in SR without AAD. One patient (5.5%) remained in SR on AAD following a single procedure and 1 patient (5.5%) remained in SR on AAD following multiple procedures. Five patients (27%) had reduced burden of symptoms and 3 patients (16.6%) had no improvement. CONCLUSION: PVI using multi-electrode mapping and ablation catheters is an effective treatment of paroxysmal and persistent AF with a complication rate equivalent to published data.