The German CPU registry: Comparison of smokers and nonsmokers

BACKGROUND

Chest pain is a major reason for admission to an internal emergency department, and smoking is a well-known risk factor for coronary artery disease (CAD) and acute coronary syndrome (ACS). The aim of this analysis is to illustrate the differences between smokers and nonsmokers presenting to German chest pain units (CPU) in regard to patient characteristics, CAD manifestation, treatment strategy, and prognosis.

METHODS

From December 2008 to March 2014, 13,902 patients who had a complete 3‑month follow-up were enrolled in the German CPU registry. The analysis comprised 5796 patients with ACS and documented smoking status.

RESULTS

Of all the patients in the CPU registry, 35.2% were smokers. Compared with nonsmokers, they were 13.5 years younger (58.2 vs. 71.7 years, p < 0.001), predominantly men (77.1% vs. 65.2%, p < 0.001), and were more frequently diagnosed with single-vessel disease (32.1% vs. 25.2%) as well as ST-elevation myocardial infarction (STEMI; 23.8% vs. 15.5%, p < 0.001). Although the Global Registry of Acute Coronary Events (GRACE) Risk Score for hospital mortality was lower in the group of smokers (106.1 vs. 123.3, p < 0.001), we did not observe any differences in CPU death (0.4% vs. 0.4%, p = 0.69) and CPU major adverse cardiac event (MACE) rates (3.8% vs 2.9%, p = 0.073) between the groups. In the 3‑month follow-up, we documented higher mortality rates in the nonsmoker group (1.9% vs. 2.9%, p = 0.035) in correlation with the GRACE Risk Score (80.3 vs. 105.2, p < 0.001). MACE rates were similar during the follow-up (3.1% vs. 4.1%, p = 0.065).

CONCLUSION

Observations from the German CPU registry demonstrate that smoking is a strong predictor of acute CAD manifestation early in life, especially STEMI. In spite of a lower GRACE Risk Score and fewer comorbidities, smokers had a rate of hospital mortality similar to the older group of nonsmokers.

Characterisation of the stbD/E toxin-antitoxin system of pEP36, a plasmid of the plant pathogen Erwinia pyrifoliae

pEP36 is a plasmid ubiquitously present in Erwinia pyrifoliae, a pathogen which causes black stem blight of Asian pear. pEP36 is highly stable in its host, even in the absence of selective pressure. The plasmid is closely related to pEA29, which is widespread in E. amylovora, the causative agent of fire blight of apple and pear trees. Here we report that pEP36 possesses a functional hybrid toxin-antitoxin module, stbD/E(pEP36), with the toxin showing homology to the RelE/ParE proteins and the antidote belonging to the Phd/YefM antitoxin family. Bacteria expressing the StbE(pEP36) toxin arrest cell growth and enter a viable but non-culturable stage. However, they maintain their typical cell length and do not show filamentation. Pulse-chase experiments revealed that StbE(pEP36) acts as a global inhibitor of protein synthesis while it does not interfere with DNA and RNA synthesis. The StbD(pEP36) antitoxin is capable of neutralising StbE(pEP36) toxicity. Additional experiments show that the stbD/E(pEP36) module can stabilise plasmids at least 20-fold. Thus the toxin-antitoxin system may contribute to the remarkable stability of pEP36.

Changes of QT dispersion in patients with coronary artery disease dependent on different methods of stress induction

BACKGROUND

Episodes of stress-induced myocardial ischemia in patients with coronary artery disease (CAD) may cause increases of QT dispersion (QTd).

HYPOTHESIS

Aim of this study was to analyze the effect of increasing heart rates on QTd and to compare the effect of different methods of stress induction in patients with varying degrees of CAD when estimating QTd.

METHODS

We studied 58 patients, 22 with prior myocardial infarction (MI), 25 without MI or wall motion disturbances at rest, and 11 patients without evidence of CAD. Prior to coronary angiography, standard 12-lead ECGs were obtained at rest as well as during dynamic exercise and pharmacologic stress using arbutamine simultaneously with echocardiography. QTd was determined at each stress level by subtracting minimal from maximal QT interval duration.

RESULTS

QTd values at rest were not consistently higher in the patients with CAD. At maximal heart rate, QTd was statistically significantly higher in patients with CAD with a better discrimination between groups for pharmacologic stress (p < 0.005 for exercise, p < 0.0001 for arbutamine). Patients after MI had higher QTd values under all conditions than did the groups without MI. As in patients with CAD, the values of this group changed more radically as a result of pharmacologic stress.

CONCLUSION

Patients with CAD can be identified on the basis of QTd under stress. These changes were not as marked in patients with MI as their rest values were already increased. Overall, drug-induced stress produced greater differences than dynamic exercise, suggesting that the ischemic threshold might be lower in the former.

Detection of coronary artery disease with MCG

The diagnosis of cardiac ischemia related to coronary artery disease (CAD) is a clinical challenge. Despite many methods clinically available, the predictive value of each is still limited. Magnetocardiography (MCG) offers new insights in the electrogenesis of the disease. In the last decade a number of studies using biomagnetometers have dealt with the identification of CAD patients using coronary angiography as a gold standard. As the availability of these systems is limited, studies have focused either on exercise-induced ischemia or on chronic ischemia and the infarct scar at rest. Different parameters have been developed based on signal morphology, time intervals, source parameters or magnetic field map analysis. Concerning signal morphology, main work concentrates on ST-depression, ST-T signal amplitude as well as QRS and ST-T integrals. Dealing with time intervals, most studies focus on the QT interval. The evaluation of of QT dispersion spatially in the MCG, reflecting regional heterogeneity of repolarization, improved the identification of CAD patients. Besides the calculation of the equivalent current dipole during de- and repolarization, parameters of the magnetic field orientation were used to identify CAD patients and localize exercise-induced ischemic regions. Heart rate adjusted alteration in the magnetic field orientation allowed the quantification of ischemia-induced changes in MCG. The estimation of current density (CDV) further enabled to separate healthy subjects from CAD patients at rest. In the course of interventional therapy CDV maps returned toward that of healthy subjects.Thus, there is justification for routine clinical use of the MCG in the diagnosis of CAD.

Magnetocardiography in the diagnosis of fetal arrhythmia

OBJECTIVE

To examine the possible use of magnetocardiography in the diagnosis of fetal arrhythmias.

DESIGN

Investigation of routinely examined pregnant women, as well as women referred because of arrhythmias or other reasons.

PARTICIPANTS

Sixty-three women between the 13th and 42nd week of pregnancy.

METHODS

Recording of 189 fetal magnetocardiograms, of which 173 traces (92%) demonstrated sufficient fetal signal strength to permit evaluation. After digital subtraction of the maternal artefact, all fetal complexes were identified and the recording was examined for arrhythmic events.

RESULTS

Short bradycardic episodes, not associated with any pathological condition, were found in 26% of all recordings, usually in mid-pregnancy. In 12 cases, isolated extrasystoles of no clinical importance could be identified. There were nine traces which revealed multiple arrhythmias including ventricular and supraventricular ectopic beats, bigeminy and trigeminy, sino-atrial block and atrio-ventricular conduction disturbances. Furthermore, two cases with tachycardia were found.

CONCLUSION

Magnetocardiography offers a simple noninvasive method for examination of the fetal cardiac electrophysiological signal. It may thus be useful in the identification and classification of clinically relevant arrhythmia and aid in decisions concerning treatment.

Spatial distribution of QT dispersion measured by magnetocardiography under stress in coronary artery disease

This study investigated changes in spatial distribution of QT duration in patients with and without coronary artery disease (CAD) using magnetocardiography. Thirty-six-channel magnetocardiograms (MCGs) were registered at rest and under stress in 15 patients with chest pain, seven of whom had significant coronary stenosis. QT dispersion (QTd) was calculated for MCG and 12-lead electrocardiogram (ECG) under both conditions. For MCG, homogeneity of repolarization was measured using a smoothness index (SI). Also, at each registration site, the intraindividual difference between QT at rest and under stress was determined (deltaQT). QTd values as determined by standard 12-lead configurations were not significantly different between groups. MCG QTd values were significantly higher in the CAD group at rest only when all available channels were taken into consideration (P < .05); SI values differed significantly between groups under both conditions (rest, P < .005; stress, P < .01). Good separation between groups was possible using the range of deltaQT (P < .05) and SI (deltaQT) (P < .005). Consideration of the spatial distribution of QTd increases its sensitivity in the detection of CAD, suggesting that CAD involves complex changes in repolarization, not apparent in limited lead sets such as standard 12-lead configurations.

[Relevance of magnetocardiography in coronary artery disease and myocardial infarction]

Multichannel magnetocardiography (MCG) noninvasively registers the magnetic activity of the heart at different points above the thorax. This information can be used to determine the magnetic field produced by cardiac activity as well to reconstruct the current density distribution in the myocardium, which can then be examined during cardiac de- and repolarisation. First studies have shown that the detection of disease specific changes of the magnetic field and current density permit the diagnosis and localization of myocardial infaction (MI) and myocardial ischemia within the context of coronary artery disease (CAD). In these studies various approaches were used to quantify and condense the temporal and spatial changes in the magnetic signals. The integration of defined time intervals of cardiac de- and repolarisation in form of iso-integral magnetic field maps allowed a discrimination between myocardial infarct groups. Furthermore residual maps, calculated by subtracting the MCG map components of MI patients from those of normal subjects, were used to describe the infarcted region. On the basis of trajectory plots which represent the course of magnetic map extrema, patients with ventricular tachycardia after MI could be identified. Current density reconstruction during ST-segment permitted the visualization of biological injury currents during induced ischemia and infarction. Beyond the consideration of the overall magnetic activity, the signal in single channels may be examined and interpreted as is done in the body surface electrocardiogram. Morphological criteria such as the course of the ST-segment as well as the spatial distribution of cardiac time intervals may be considered. Risk stratification of patients after MI with regard to an increased risk of malignant arrhythmia is possible by making use of the spatial distribution of QT dispersion. The promising preliminary results suggest that the current methods must be developed and investigated further in studies with the appropriate number and kind of subjects in order to assess the clinical value of the MCG in patients with CAD and MI.

[Clinical experience with combined automatic implantable cardioverter-defibrillator and pacemaker systems]

Patients who need an implantable Cardioverter/Defibrillator (ICD) often require a cardiac pacemaker (PM) to treat underlying symptomatic bradycardia. In some cases the simultaneous therapy has caused interactions between the systems with defaults on both sides.Four patients with an ICD of the newer generation received a single or dual chamber pacemaker system. In all cases bipolar pacemaker electrodes were used. They were positioned together with the ICD-electrode in the right ventricular apex without regard to the distance between them. In order to exclude possible interference between systems special tests were performed during the operative procedure with respect to the system implanted first. In a follow-up period of 4-14 months all patients had episodes of ventricular tachycardia or ventricular fibrillation that were terminated successfully. Two patients with a bradycardia related arrhythmia after shock delivery showed a correct pacemaker stimulation. Subsequent to the start of pacemaker therapy improvement in stress capacity could be documented, partly on the basis of echocardiography.Combined ICD and PM therapy can thus be generally regarded as compatible. For AV-sequential pacing at least three electrodes and two aggregates are necessary. The development of an ICD with the option for a dual-chamber stimulation would simplify the therapy, along with a greater acceptance on part of the patients.

Spatial distribution of QT intervals: an alternative approach to QT dispersion

QT dispersion (QTd) describes the heterogeneity of ventricular repolarization on the basis of the temporal range of QT intervals as measured in the 12-lead ECG. We examined the spatial distribution of QTd using multichannel magnetocardiograms (MCGs), which noninvasively register changes in magnetic field strength at 37 sites over the heart. As in ECG, the MCG signal in each channel may be used to measure QT interval. By calculating QT deviation from QTmin at each site, one can reconstruct the spatial distribution of QTd. Analysis of spatial QTd in ten healthy subjects and ten patients after acute myocardial infarction (MI) showed clear differences in spatial distribution. The healthy subjects generally displayed shorter QT intervals along a line corresponding to the approximate position of the septum with longer intervals in plateaus in the upper right and lower left. Spatial QTd of the post-MI patients deviated from this pattern, often displaying a sharp rise in QT duration over specific areas, which could be related to functional and morphological disturbances. The quantification of local irregularities as well as the overall pattern on the basis of a smoothness index allowed better discrimination between healthy subjects and post-MI patients than QTd. Distribution patterns of QTd which reflect local repolarization alterations may thus represent a more differentiated marker for pathology and risk.