Hans-Henrik Tilsted Hansen

Routine thrombectomy in percutaneous coronary intervention for acute ST-segment-elevation myocardial infarction: a randomized, controlled trial.

Background— Distal embolization during primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction may result in reduced myocardial perfusion, infarct extension, and impaired prognosis. Methods and Results— In a prospective randomized trial, we studied the effect of routine thrombectomy in 215 patients with ST-segment–elevation myocardial infarction lasting <12 hours undergoing primary PCI. Patients were randomized to thrombectomy pretreatment or standard PCI. The primary end point was myocardial salvage measured by sestamibi SPECT, calculated as the difference between area at risk and final infarct size determined after 30 days (percent). Secondary end points included final infarct size, ST-segment resolution, and troponin T release. Baseline variables, including ST-segment elevation and area at risk, were similar. Salvage was not statistically different in the thrombectomy and control groups (median, 13% [interquartile range, 9% to 21%] and 18% [interquartile range, 7% to 25%]; P=0.12), but 24 patients in the thrombectomy group and 12 patients in the control group did not have an early SPECT scan, mainly because of poor general or cardiac condition (P=0.04). In the thrombectomy group, final infarct size was increased (median, 15%; [interquartile range, 4% to 25%] versus 8% [interquartile range, 2% to 18%]; P=0.004). Conclusions— Thrombectomy performed as routine therapy in primary PCI for ST-elevation myocardial infarction does not increase myocardial salvage. The study suggests a possible deleterious effect of thrombectomy, resulting in an increased final infarct size, and does not support the use of thrombectomy in unselected primary PCI patients.

Drug-Eluting Versus Bare Metal Stents in Patients With ST-Segment–Elevation Myocardial Infarction Eight-Month Follow-Up in the Drug Elution and Distal Protection in Acute Myocardial Infarction (DEDICATION) Trial

Background— Implantation of drug-eluting stents (DES) limits the rate of coronary restenosis in most patients with coronary artery disease, but data are scarce with regard to their use in patients with ST-segment–elevation myocardial infarction and in connection with distal protection of the microvascular perfusion during primary percutaneous coronary intervention. Methods and Results— We randomly assigned 626 patients referred within 12 hours from symptom onset of an ST-elevation myocardial infarction to have a DES or a bare metal stent implanted in the infarct-related lesion with or without distal protection during primary percutaneous coronary intervention. Quantitative coronary angiography was performed during the index treatment and 8 months later. The primary end point was loss of the lumen diameter in the infarct-related lesion induced by neointimal proliferation. Patients were comparable with regard to baseline demographic and angiographic characteristics. The mean late lumen loss was significantly lower in patients treated with a DES (0.06 mm; SD, 0.66 mm) than in patients who had a bare metal stent implanted (0.47 mm; SD, 0.69 mm; P<0.001). The rate of the composite end point of cardiac death, recurrent myocardial infarction, and target lesion revascularization was 8.6% in the DES group versus 14.4% in the bare metal stent group (P=0.03). Cardiac death occurred in 4.2% and 1.6% of the patients (P=0.09) and stent thrombosis occurred in 2.0% and 2.6% (P=0.72), respectively. Conclusion— Implantation of DES improves the angiographic outcome and need for repeat revascularization without increasing the short-term risk of stent thrombosis but has a tendency to increase cardiac death in patients with ST-segment–elevation myocardial infarction.

A new optimized space vector modulation strategy for a component minimized voltage source inverter

This paper presents a new space vector modulation strategy suitable for a low cost PWM-VSI inverter employing only four switches, four diodes and a split capacitor bank in the DC-link. The work is motivated by the need of an efficient and flexible modulation method, which is optimized with respect to minimum machine torque ripple. The modulation strategy is named Space Vector Modulation for Four Switch Inverter (SVMFSI) and is realized by planning the switching patterns between four active voltage vectors on the basis of a desired flux trajectory for the stator flux vector in the AC-machine (variable speed induction motor drive). The strategy is implemented in a single 8-bit microcontroller as a double sided modulation strategy. Simulations of the motor torque ripple are performed at a switching frequency of 4 kHz and indicate a torque ripple of 14% at nominal load. Finally, selected results are verified experimentally on a 1.5 kVA prototype B4 inverter. The test results indicate high quality output voltage spectra with no low-order voltage harmonics and a harmonic loss factor (HLF) of 1.12% at unity modulation index.<<ETX>>

Can soft-starters help save energy?

This article describes results of an experimental evaluation of seven commercial soft-starters used with three motors of different power ratings. Several performance indicators have been measured and compared to illustrate operation of soft-starters and assess their energy-saving capabilities. Three standard squirrel-cage induction motors, rated at 3 kW, 7.5 kW, and 22 kW, were used. Several European manufacturers provided soft-starters for the investigation. Tests were performed under the steady-state and transient operating conditions.

In-hospital outcome for diabetic patients with acute myocardial infarction in the thrombolytic era.

A 3-year retrospective study was carried out at the Department of Cardiology, Aalborg Hospital, Denmark. The aim of the study was to investigate the in-hospital mortality and complications resulting from acute myocardial infarction in diabetic patients compared with non-diabetic patients in the thrombolytic era and to investigate the correlation between mortality and blood glucose levels in diabetic patients. All patients admitted to the study suffered acute myocardial infarctions. One hundred and twenty-three patients with diabetes and 856 patients without diabetes were included. Mortality was 13% (110 patients) in non-diabetic patients compared with 28% (34 patients) in diabetic patients (p = 0.00002). Eighty-nine patients with diabetes (72%) experienced heart failure or a worsening of heart failure compared with 424 patients without diabetes (50%), p = 0.00001. Twenty-eight diabetic patients (23%) had high-degree atrioventricular block, compared with only 99 non-diabetic patients (12%), p = 0.001. Atrial fibrillation developed in 35 patients with diabetes (28%) and in only 141 patients without diabetes (16%), p = 0.002. No difference was seen in occurrence of ventricular tachyarrhythmias. Diabetic patients with a fatal outcome had significantly higher blood glucose values at admission compared with diabetic patients who survived (17.1 +/- 8.3 vs 13.5 +/- 6.3 mmol/l; p = 0.034), and during hospitalization (85.7 +/- 26.0% of blood glucose values exceeding 10 mmol/l vs 64.5 +/- 33.1; p = 0.00065). In the thrombolytic era diabetic patients with acute myocardial infarction had a higher mortality and experienced more complications during hospitalization compared with non-diabetic patients, and diabetic patients with a fatal outcome had higher blood glucose levels compared with surviving diabetic patients.

Comparison of Stent Thrombosis, Myocardial Infarction, and Mortality Following Drug-Eluting Versus Bare-Metal Stent Coronary Intervention in Patients With Diabetes Mellitus

The aim of this study was to examine outcomes subsequent to implantation of drug-eluting stents (DESs) and bare-metal stents (BMSs) in patients with diabetes. From January 2002 to June 2005, data from all percutaneous coronary interventions performed in Western Denmark were prospectively recorded. A total of 1,423 consecutive diabetic patients treated with stent implantation (2,094 lesions) were followed up for 15 months. Of these, 871 patients (1,180 lesions) were treated with a BMS, and 552 patients (914 lesions) were treated with a DES. Dual antiplatelet therapy was recommended for 12 months in both treatment groups. Data for death and myocardial infarction (MI) were ascertained from national health care databases. Use of DESs was not associated with increased risk of definite stent thrombosis (adjusted relative risk [RR] 0.76, 95% confidence interval [CI] 0.10 to 3.26) or MI (adjusted RR 0.90, 95% CI 0.53 to 1.52). In the DES group compared with the BMS group, adjusted RRs of target-lesion revascularization (adjusted RR 0.48, 95% CI 0.33 to 0.71), total mortality (adjusted RR 0.66, 95% CI 0.44 to 0.99), and cardiac mortality (adjusted RR 0.53, 95% CI 0.31 to 0.90) decreased by 52%, 34%, and 47%, respectively. In conclusion, use of DESs reduced target-lesion revascularization in diabetic patients receiving routine clinical care. This result was obtained without increased risk of death, stent thrombosis, or MI.

Short and long-term outcome in diabetic patients with acute myocardial infarction in the invasive era.

Objectives. To investigate the outcome after acute myocardial infarction in diabetic patients compared with non-diabetic patients in a period with invasive treatment as the preferred treatment for acute myocardial infarction (MI). Design. Patient records for all patients admitted with an acute MI in a two-year period from July 1, 2001 to June 30, 2003 were reviewed. Results. A total of 334 patients entered the study: 48 with diabetes mellitus (DM) and 286 without diabetes. ST-elevation infarction occurred in 49% of non-diabetic patients and 36% of diabetic patients. In-hospital mortality was 23% among diabetic patients compared to 5% among non-diabetic patients (p < 0.001). Long-term mortality (median 2 years and 10 months) was 44% in diabetic-patients and 23% in non-diabetic patients (p = 0.001). Diabetic patients were older, more frequently had hypertension and three-vessel disease, but DM was found to be an independent risk factor for death after MI (p = 0.005). Conclusions. In an era of invasive therapy as the preferred therapy for acute MI, DM is still associated with considerably increased mortality after an acute MI.

A response to a misrepresentation of the STEMI guidelines: the response

The Authors’ reply We appreciate the opportunity to comment on the reply to the counterpoint of our editorial.1 ,2 Admittedly, the comments were edgy, but the content was intended to be a scientific exchange regarding the interpretation of the European Society of Cardiology guidelines based on the best available evidence. Our position stems, in part, from a more regional than perhaps international perspective where guidelines are read by lawyers and politicians, who sometimes interpret statements out of context. Our mission was simply to address a prevalent confusion regarding ‘Percutaneous Coronary Intervention (PCI)-related delay’ and point out that in some paragraphs of the comprehensive 2012 European Society of Cardiology ST-Elevation Myocardial Infarction (STEMI) guidelines3 ‘PCI-related delay’ seems to be equated with ‘time from First Medical Contact (FMC) to Primary PCI (PPCI) delay’, since data addressing ‘PCI-related delay’ have been used to give recommendations concerning ‘FMC to PPCI delay’. In paragraph 3.5.2 the guidelines3 thoroughly discuss the paper by Pinto and colleagues4 (ref. 41 in the guidelines) and states: “Taking into account the …

A comparative study of energy saving benefits in softstarters for three-phase induction motors

Modern soft-starters have both soft-starter capability and energy saving functions which are special useful when the motor runs at low load. This paper investigates modern soft-starters for induction motors at three different power levels (3 kW, 7.5 kW and 22 kW). The investigation includes efficiency measurements, start-up measurements and measurement of the grid current harmonics at different loads to investigate the soft-starters performance against new regulations. The measurements are compared with an induction motor without soft-starters. It is concluded soft-starters have energy saving capabilities at low load up to 4% of rated power for small motors, but it is also concluded the payback time will be long. Finally, it is concluded soft-starters have problems with new grid disturbance regulations at low load operation.