Mehmood Zeb

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.

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.

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 Fishers 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.

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.

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.

Left and right parasternal sensing for the S-ICD in adult congenital heart disease patients and normal controls

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.

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.

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.

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 (McNemars 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.

5 Surface Electrocardiogram Signals Variation with Posture in Normal Adults and in Adults with Congenital Heart Disease and its Clinical Implication

Introduction Ambulatory cardiac monitoring devices and the novel subcutaneous ICD (SICD) sensing algorithms are based on the surface electrocardiograms (ECGs) parameters for detection and discrimination of arrhythmias. However the impact of posture, cardiac morphologies (normal and congenital heart diseases), and electrode placement on these parameters are not known. Aim To determine the impact of posture (standing, sitting, supine, left lateral, right lateral) and bipolar electrode location (LI, LII, LIII), cardiac morphologies (normal, TOF, TGA, SVP) and gender on R-wave amplitude, T-wave amplitude, R/T ratio, QRS, QTc, Tpeak-end duration. Method 720 bipolar vectors were collected in a set of three lead (LI, LII, LIII) transcutaneous ECGs at gain 10, at a speed 25mm/sec from three location of SICD sensing arrays in 6 postures from 40 patients including 10 normal controls, 10TOF, 10 SVP, 10 TGA. The ECGs were digitally measured and analysed using repeated-measures ANOVA and Post hoc Helmert contrast pair wise analysis with Bonferroni adjustment. A p value of less than 0.05 was considered significant. Results The mean R-wave amplitude was significantly smaller in LI than LIII (p = 0.025), and right lateral posture in comparison to left lateral posture (p = 0.02). The T-wave amplitude in individuals with TOF was significantly greater than individuals with normal cardiac morphology (p = 0.013) and SVP (p = 0.005). The mean QRS duration in individuals with normal cardiac morphology was significantly smaller than individuals with TOF (p = 0.0001) and SVP (p = 0.006). Also the mean QRS duration in female was significantly smaller than male (p = 0.03). There were no statistically significant differences in the mean R/T ratio, QTc interval, Tpeak-end duration between subgroups, six postures and three lead (p > 0.05). Conclusion Postures, electrodes location and cardiac morphologies have impact on the surface ECG morphological components which may have to be considered while designing sensing algorithm of monitoring devices and specifically SICD.