WCTECGdb: A 12-Lead Electrocardiography Dataset Recorded Simultaneously with Raw Exploring Electrodes' Potential Directly Referred to the Right Leg.

With this paper we communicated the existence of a surface electrocardiography (ECG) recordings dataset, named WCTECGdb, that aside from the standard 12-lead signals includes the raw electrode biopotential for each of the nine exploring electrodes refereed directly to the right leg. This dataset, comprises of 540 ten second segments recorded from 92 patients at Campbelltown Hospital, NSW Australia, and is now available for download from the Physionet platform. The data included in the dataset confirm that the Wilson's Central Terminal (WCT) has a relatively large amplitude (up to 247% of lead II) with standard ECG characteristics such as a p-wave and a t-wave, and is highly variable during the cardiac cycle. As further examples of application for our data, we assess: (1) the presence of a conductive pathway between the legs and the heart concluding that in some cases is electrically significant and (2) the initial assumption about the limbs potential stating the dominance of the left arm concluding that this is not always the case and that might requires case to case assessment.

On the Einthoven Triangle: A Critical Analysis of the Single Rotating Dipole Hypothesis.

Since its inception, electrocardiography has been based on the simplifying hypothesis that cardinal limb leads form an equilateral triangle of which, at the center/centroid, the electrical equivalent of the cardiac activity rotates during the cardiac cycle. Therefore, it is thought that the three limbs (right arm, left arm, and left leg) which enclose the heart into a circuit, where each branch directly implies current circulation through the heart, can be averaged together to form a stationary reference (central terminal) for precordials/chest-leads. Our hypothesis is that cardinal limbs do not form a triangle for the majority of the duration of the cardiac cycle. As a corollary, the central point may not lie in the plane identified by the limb leads. Using a simple and efficient algorithm, we demonstrate that the portion of the cardiac cycle where the three limb leads form a triangle is, on average less, than 50%.

Influence of Age and Gender on Clinical Outcomes Following Percutaneous Coronary Intervention for Acute Coronary Syndromes.

BACKGROUND: Gender and age are non-modifiable factors influencing clinical outcomes in acute coronary syndromes (ACS). There is evidence that coronary artery disease pathophysiology varies in women. We therefore evaluated the effect of age and gender on clinical outcomes in patients with ACS undergoing percutaneous coronary interventions (PCI). METHODS: Among 3178 (25% female) consecutive ACS patients who underwent PCI at Liverpool Hospital, Sydney from 2003 to 2010, using femoral access in 98% of cases, we determined late events including mortality, myocardial infarction and bleeding according to Bleeding Academic Research Consortium (BARC) criteria. RESULTS: Females compared with males were older (median 68 vs. 60 years; p<0.001), and were more likely to have diabetes (30% vs. 22% p<0.001), hypertension (62% vs. 49%, p<0.001), anaemia (26% vs. 15%, p<0.001), and renal impairment (43% vs. 20%, p<0.001); they were more likely to be non-smokers (19% vs. 30%, p<0.001). Females had less class B2/C lesions (64% vs.68%, p=0.048), but had more calcified lesions (20% vs. 11%, p<0.001), and smaller stent diameters (2.75[2.5-3.0] vs. 3.0[2.75-3.5] mm, p<0.001). Females had higher three-year mortality rates (11% vs. 7.0%, p=0.001), and more type 2-5 BARC bleeding post-PCI (22% vs. 16%, p=0.003). Among patients under 55 years (n=988), mortality and bleeding were higher in females (6.0% vs. 3.0%, p=0.028) and (26% vs. 14%, p=0.001) respectively. There was no effect of gender on mortality or bleeding in patients 55 years and over. However, on multivariable stepwise regression analysis, female gender was not an independent predictor of mortality, but was a significant predictor of bleeding (OR=1.84 [95% CI:1.38-2.45], p<0.001). CONCLUSION: Bleeding and mortality were higher in younger females with ACS who underwent PCI. While females had more post-PCI bleeding events, which were associated with late mortality, gender per se was not an independent predictor for mortality.

Evaluation of Serial High Sensitivity Troponin T Levels in Individuals Without Overt Coronary Heart Disease Following Exercise Stress Testing.

BACKGROUND: Detectable levels of high sensitivity (cardiac) troponin T (HsTnT), occur in the majority of patients with stable coronary heart disease (CHD), and often in 'healthy' individuals. Extreme physical activity may lead to marked elevations in creatine kinase MB and TnT levels. However, whether HsTnT elevations occur commonly after exercise stress testing (EST), and if so, whether this has clinical significance, needs clarification. METHODS: To determine whether HsTnT levels become elevated after EST (Bruce protocol) to ≥95% of predicted maximum heart rate in presumed healthy subjects without overt CHD, we assayed HsTnT levels for ∼5h post-EST in 105 subjects (median age 37 years). RESULTS: Pre-EST HsTnT levels <5 ng/L were present in 31/32 (97%) of females and 52/74 (70%) of males. Post-EST, 13 (12%) subjects developed HsTnT levels >14 ng/L, with troponin elevation occurring at least three hours post-EST. Additionally, a detectable ≥ 50% increase in HsTnT levels (4.9→9ng/L) occurred in 28 (27%) of subjects who during EST achieved ≥ 95% of their predicted target heart rate. The median age of the subjects with HsTnT elevations to > 14ng/L post-EST was higher than those without such elevation (42 and 36 years respectively; p=0.038). At a median follow-up of 13 months no adverse events were recorded. CONCLUSION: The current study demonstrates that detectable elevations occur in HsTnT post-EST in 'healthy' subjects without overt CHD. Future studies should evaluate the clinical significance of detectable elevations in post-EST HsTnT with long-term follow-up for adverse cardiac events.

Safety and efficacy of same-day discharge following elective percutaneous coronary intervention, including evaluation of next day troponin T levels.

BACKGROUND: As patients are increasingly undergoing elective percutaneous coronary intervention (PCI) with same-day discharge (SDD), and as post-PCI troponin T (TnT) elevations are associated with increased rates of death/myocardial infarction (MI) following elective PCI, we examined late outcomes with respect to post-PCI TnT elevations in patients undergoing SDD. METHODS AND RESULTS: We studied 303 patients (mean age 62±9years, 89% male) who underwent elective-PCI between October 2007 and September 2012, of whom 149 had SDD and 154 stayed overnight (ON) who were age-and sex-matched. Eligibility for SDD excluded patients with: multi-vessel PCI, proximal LAD lesions, chronic total occlusions, side branch occlusions, or access site complications. Femoral access rates were 72% and 96% among SDD and ON patients respectively. Post-PCI, SDD patients left at 4.40[4.13-5.30]hours, and ON patients left at 23.44[21.50-25.41]hours (p<0.001). Overall 8.45% met the 2012 universal MI definition. No patients were re-hospitalised within 48hours. At 30-days, unplanned cardiac re-hospitalisation rates were 3.4% and 0.7% among SDD and ON patients (p=0.118); the only event was MI in an SDD patient. At 16[9-32] months, rates of death, MI, target vessel revascularisation, stroke, were 1.3%,1.3%,2.7% and 1% respectively; the composite rate was 6%(6.1% SDD; 6% ON; p=0.965). Late death/MI rates among patients with, and without, post-PCI TnT levels≥5xURL were 3.4% and 2.8% respectively (p=0.588). CONCLUSION: SDD following elective PCI among low risk patients appears to be safe and ≥5 fold post-PCI TnT elevations did not appear to confer incremental short and long term risk. A larger cohort is required to confirm this observation.

Bare-metal stenting of large coronary arteries in ST-elevation myocardial infarction is associated with low rates of target vessel revascularization.

BACKGROUND: During percutaneous coronary intervention (PCI) performed in the emergent setting of ST-segment elevation myocardial infarction (STEMI), uncertainty about patients' ability to comply with 12 months dual antiplatelet therapy after drug-eluting stenting is common, and thus, selective bare-metal stent (BMS) deployment could be an attractive strategy if this achieved low target vessel revascularization (TVR) rates in large infarct-related arteries (IRAs) (≥3.5 mm). METHODS AND RESULTS: To evaluate this hypothesis, among 1,282 patients with STEMI who underwent PCI during their initial hospitalization, we studied 1,059 patients (83%) who received BMS, of whom 512 (48%) had large IRAs ≥3.5 mm in diameter, 333 (31%) had IRAs 3 to 3.49 mm, and 214 (20%) had IRAs <3 mm. At 1 year, TVR rate in patients with BMS was 5.8% (2.2% with large BMS [≥3.5 mm], 9.2% with BMS 3-3.49 mm [intermediate], and 9.0% with BMS <3.0 mm [small], P < .001). The rates of death/reinfarction among patients with large BMS compared with intermediate BMS or small BMS were lower (6.6% vs 11.7% vs 9.0%, P = .042). Among patients who received BMS, the independent predictors of TVR at 1 year were the following: vessel diameter <3.5 mm (odds ratio [OR] 4.39 [95% CI 2.24-8.60], P < .001), proximal left anterior descending coronary artery lesions (OR 1.89 [95% CI 1.08-3.31], P = .027), hypertension (OR 2.01 [95% CI 1.17-3.438], P = .011), and prior PCI (OR 3.46 [95% CI 1.21-9.85], P = .02). The predictors of death/myocardial infarction at 1 year were pre-PCI cardiogenic shock (OR 8.16 [95% CI 4.16-16.01], P < .001), age ≥65 years (OR 2.63 [95% CI 1.58-4.39], P < .001), left anterior descending coronary artery culprit lesions (OR 1.95 [95% CI 1.19-3.21], P = .008), female gender (OR 1.93 [95% CI 1.12-3.32], P = .019), and American College of Cardiology/American Heart Association lesion classes B2 and C (OR 2.17 [95% CI 1.10-4.27], P = .026). CONCLUSION: Bare-metal stent deployment in STEMI patients with IRAs ≥3.5 mm was associated with low rates of TVR. Their use in this setting warrants comparison with second-generation drug-eluting stenting deployment in future randomized clinical trials.

Evaluation of a policy of selective drug-eluting stent implantation for patients at high risk of restenosis.

Drug-eluting stent (DES) deployment during percutaneous coronary intervention (PCI) has reduced target-vessel revascularisation rates (TVR). The selective use of DES in patients at highest risk of restenosis may allay concerns about universal compliance of dual antiplatelet therapy for one year, and potentially reduce costs. If this strategy achieved acceptably low TVR rates, such an approach could be attractive. Late clinical outcomes were examined in 2115 consecutive patients (mean age 63±12 years, 75% male, 22% diabetics) who underwent PCI in the first three years from October 2003, after commencing the following selective criteria for DES use: left main stenosis; ostial lesions of major epicardial arteries; proximal LAD lesions; lesions≥20mm in length with vessel diameter≤3.0mm; lesions in vessels≤2.5mm; diabetics with vessel(s)≤3.0mm; and in-stent restenosis. Among patients undergoing PCI, 2075 (98%) patients received stents (29%≥1 DES and 71% bare metal stent [BMS]), and among those who received DES, there was a 92% compliance with these criteria. There were no differences in clinical outcomes between the two stent groups except for definite stent thrombosis, which occurred in 2% after DES, and 0.6% after BMS at one year (p=0.002). With BMS, large coronary arteries (≥3.5mm), intermediate (3-3.49mm) and small arteries (<3mm) in diameter had a TVR rate at one year of 3.6%, 7.2% and 8.2% respectively (p=0.005). It is possible to use selective criteria for DES while maintaining low TVR rates. The TVR rate with BMS was low in those with stent diameters≥3.5mm. The higher DES stent thrombosis rate reflects first generation DES use, though whether routine second generation DES use reduces these rates needs confirmation.

Sex Differences in Outcome and Prescribing Practice in ST-elevation MI Patients with Multivessel Disease and Incomplete Revascularisation.

Objective: To investigate the extent to which multivessel disease, incomplete revascularisation and prescribing differences contribute to sex-based outcome disparities in patients with ST-elevation MI (STEMI) and establish whether differences in cardiac death and MI (CDMI) rates persist at long-term follow-up. Methods and results: This observational study evaluates sex-based outcome differences (median follow-up 3.6 years; IQR [2.4-5.4]) in a consecutive cohort of patients (n=2,083) presenting with STEMI undergoing percutaneous coronary intervention). Of the studied patients 20.3% (423/2,083) were women and 38.3% (810/2,083) had multivessel disease (MVD). Incomplete revascularisation was common. The median residual SYNTAX score (rSS) was 5.0 (IQR [0-9]) in women and 5.0 (IQR [1-11]) in men (p=0.369), and in patients with MVD it was 9 (IQR [6-17]) in women and 10 (IQR [6-15]) in men (p=0.838). The primary endpoint CDMI occurred in 20.3% of women (86/423) and in 13.2% of men (219/1,660) (p=0.028). Differences persisted following multivariable risk adjustment: female sex was independently associated with CDMI (aHR 1.33; IQR [1.02-1.74]). Women with MVD had CDMI more often than all other groups (p<0.001 for all). Significant sex-based prescribing differences were evident: women were less likely to receive guideline-recommended potent P2Y12 inhibitors than men (31% versus 43%; p=0.012), and differences were particularly evident in patients with MVD (25% in women versus 45% in men, p=0.011). Conclusion: Sex-based differences in STEMI patient outcome persist at long-term follow-up. Poor outcomes were disproportionately found in women with MVD and those with rSS>8. Observed differences in P2Y12 prescribing practices may contribute to poor outcomes for women with MVD and incomplete revascularisation.

Safety and efficacy of rescue angioplasty for ST-elevation myocardial infarction with high utilization rates of glycoprotein IIb/IIIa inhibitors.

BACKGROUND: Fibrinolytic therapies remain widely used for ST-elevation myocardial infarction, and for "failed reperfusion," rescue percutaneous coronary intervention (PCI) is guideline recommended to improve outcomes. However, these recommendations are based on data from an earlier era of pharmacotherapy and procedural techniques. METHODS AND RESULTS: To determine factors affecting prognosis after rescue PCI, we studied 241 consecutive patients (median age 55 years, interquartile range [IQR] 48-65) undergoing procedures between 2001 and 2009 (53% anterior ST-elevation myocardial infarction and 78% transferred). The median treatment-related times were 1.2 hours (IQR 0.8-2.2) from symptom onset to door, 2 hours (IQR 1.3-3.2) from symptom onset to fibrinolysis (93% tenecteplase), and 3.9 hours (IQR 3.1-5.2) from fibrinolysis to balloon. Procedural characteristics were stent deployment in 95% (11.6% drug eluting) and 78% glycoprotein IIb/IIIa inhibitor use, and Thrombolysis In Myocardial Infarction (TIMI) 3 flow rates pre-PCI and post-PCI were 41% and 91%, respectively (P < .001). At 30 days, TIMI major bleeding occurred in 16 (6.6%) patients, and 23 (9.5%) patients received transfusions; nonfatal stroke occurred in 4 (1.7%) patients (2 hemorrhagic). Predictors of TIMI major bleeding were female gender (odds ratio 3.194, 95% CI 1.063-9.597; P = .039) and pre-PCI shock (odds ratio 3.619, 95% CI,1.073-12.207; P = .038). Mortality at 30 days was 6.2%, and 3.2% in patients without pre-PCI shock. One-year mortality was 8.2% (5.3% in patients without pre-PCI cardiogenic shock), 5.2% had reinfarction, and the target vessel revascularization rate was 6.4% (2.6% in arteries ≥ 3.5 mm in diameter). Pre-PCI shock, female gender, and post-PCI TIMI flow grades ≤ 2 were significant predictors of 1-year mortality on multivariable regression modeling, but TIMI major bleeding was not. CONCLUSIONS: Rescue PCI with contemporary treatments can achieve mortality rates similar to rates for contemporary primary PCI in patients without pre-PCI shock. Whether rates of bleeding can be reduced by different pharmacotherapies and interventional techniques needs clarification in future studies.

Cardiac mortality, diabetes mellitus, and multivessel disease in ST elevation myocardial infarction.

BACKGROUND: In patients with diabetes mellitus presenting with ST elevation myocardial infarction (STEMI) the degree to which cardiac death rates may be attributed to an increased burden of coronary artery disease is not clear. METHODS: This prospective observational study examines rates of cardiac death between those with and without diabetes at long term follow up, stratified by presence of multivessel disease (MVD), in consecutive STEMI patients from 5 Australian hospitals. RESULTS: Amongst 2083 patients, 393 patients had diabetes (18.8%), and 810 (38.8%) had MVD. Patients with diabetes were more likely to have MVD 48.6% (191/393) than patients without diabetes 36.6% (619/1690; p < .001). At final follow up (median 3.6 years [IQR 2.4-5.4]) cardiac death occurred in 37/393 diabetic patients and 92/1690 nondiabetic patients (adjusted HR1.67, 95% CI 1.10-2.52). In those with MVD cardiac death occurred in 27/191 diabetic patients, and 54/619 non-diabetic patients (adjusted HR 1.94; 95% CI 1.17-3.23). In single vessel disease (SVD) cardiac death occurred in 10/202 diabetic patients, and 38/1071 non-diabetic patients (adjusted HR 1.37; 95% CI 0.65-2.89). Both diabetes and MVD were independently associated with cardiac death. CONCLUSIONS: STEMI patients with diabetes are more likely to have MVD, with an absolute difference in MVD rates of 12%, and higher rates of cardiac death. Randomized trials studying these high risk patients are needed to reduce cardiac mortality in patients with diabetes, MVD and STEMI.

Minimization of the Wilson's Central Terminal voltage potential via a genetic algorithm.

OBJECTIVE: The Wilson Central Terminal (WCT) is an artificially constructed reference for surface electrocardiography, which is assumed to be near zero and steady during the cardiac cycle; namely it is the simple average of the three recorded limbs (right arm, left arm and left leg) composing the Einthoven triangle and considered to be electrically equidistant from the electrical center of the heart. This assumption has been challenged and disproved in 1954 with an experiment designed just to measure and minimize WCT. Minimization was attempted varying in real time the weight resistors connected to the limbs. Unfortunately, the experiment required a very cumbersome setup and showed that WCT amplitude could not be universally minimized, in other words, the weight resistors change for each person. Taking advantage of modern computation techniques as well as of a special ECG device that aside of the standard 12-lead Electrocardiogram (ECG) can measure WCT components, we propose a software minimization (genetic algorithm) method using data recorded from 72 volunteers. RESULT: We show that while the WCT presents average amplitude relative to lead II of 58.85% (standard deviation of 30.84%), our minimization method yields an amplitude as small as 7.45% of lead II (standard deviation of 9.04%).

Use of a high-sensitivity troponin T assay in the assessment and disposition of patients attending a tertiary Australian emergency department: a cross-sectional pilot study.

OBJECTIVE: We examined the disposition and outcomes of patients presenting to the ED with symptoms suggestive of acute coronary syndrome undergoing measurement of troponin T using a highly sensitive assay. METHODS: Troponin T (TnT) was measured in 204 consecutive patients (mean age = 65 [±18] years, 55% men) presenting to the ED with symptoms suggestive of acute coronary syndrome. RESULTS: Ninety-four patients predominantly had chest pain, 34 had dyspnoea and the remainder had various symptoms. Overall, 96 patients had TnT >14 ng/L (upper reference limit), of whom 31 were admitted to the cardiology service (26 had final cardiac diagnosis [five ST-elevation MI, 10 non-ST-elevation MI, one unstable angina and 10 other cardiac]). Among these 96 patients, 41 had chronic kidney disease, 17 had heart failure and seven had sepsis. At 30 days, death rates among patients who had TnT >14 ng/L with non-cardiac diagnoses and in patients who had TnT >14 ng/L with a cardiac diagnosis were 6.6% and 2.9% (P = 0.652); no death and/or MI occurred in patients with normal TnT levels. At late follow up (median 6.8 months) that was obtained in 189 (93% of 204) patients, four had MI and 14 died (three cardiac deaths). CONCLUSIONS: Despite high-sensitivity TnT assay having a high sensitivity and specificity for myocardial necrosis, the majority of unselected consecutive patients attending ED in whom TnT levels were elevated did not have an acute coronary syndrome. Our pilot study suggests that a larger study is needed to provide evidence to modify management algorithms.

Varying definitions for periprocedural myocardial infarction alter event rates and prognostic implications.

BACKGROUND: Periprocedural myocardial infarction (PMI) has had several definitions in the last decade, including the Society for Cardiovascular Angiography and Interventions (SCAI) definition, that requires marked biomarker elevations congruent with surgical PMI criteria. METHODS AND RESULTS: The aim of this study was to examine the definition-based frequencies of PMI and whether they influenced the reported association between PMI and increased rates of late death/ myocardial infarction (MI). We studied 742 patients; 492 (66%) had normal troponin T (TnT) levels and 250 (34%) had elevated, but stable or falling, TnT levels. PMI, using the 2007 and the 2012 universal definition, occurred in 172 (23.2%) and in 99 (13.3%) patients, respectively, whereas 19 (2.6%) met the SCAI PMI definition (P<0.0001). Among patients with PMI using the 2012 definition, occlusion of a side branch ≤1 mm occurred in 48 patients (48.5%) and was the most common angiographic finding for PMI. The rates of death/MI at 2 years in patients with, compared to those without, PMI was 14.7% versus 10.1% (P=0.087) based on the 2007 definition, 16.9% versus 10.3% (P=0.059) based on the 2012 definition, and 29.4% versus 10.7% (P=0.015) based on the SCAI definition. CONCLUSION: In this study, PMI, according to the SCAI definition, was associated with more-frequent late death/MI, with ≈20% of all patients, who had PMI using the 2007 universal MI definition, not having SCAI-defined PMI. Categorizing these latter patients as SCAI-defined no PMI did not alter the rate of death/MI among no-PMI patients.