Abnormal dispersion of the QT interval (QTd), measured as the interlead variability of QT, reflects an inhomogeneity of ventricular action potentials. In this study we observed both short- and ...long-term influences of coronary artery bypass grafting (CABG) on rest and exercise QTd in 64 male patients, having a mean age of 54+/-10 years, with coronary heart disease.
QTd was measured as the difference between QT maximum and minimum from 12 leads on an averaged ECG (25 mm/s). QTd and QTdc were measured at rest and at peak exercise during symptom-limited treadmill exercise (ET), which was performed before, 6 months after, and 2 years after CABG.
There was a significant reduction in rest QTd from before CABG to 6 months and 2 years after (60+/-20 ms vs. 43+/-14 ms and 45+/-13 ms, respectively; p<0.001). Similarly, there was a significant reduction in peak QTd from before CABG to 6 months and 2 years after (66+/-22 ms vs. 38+/-11 ms and 36+/-11 ms, respectively; p<0.001). Two years after CABG, 17 patients had a recurrence of angina and ET provoked chest pain and/or >2 mm ST depression. The resting values did not distinguish patients with ischemia from nonischemic ones. In patients with ischemia, ET provoked an increase in QTdc.
Rest and exercise QTd is significantly reduced after CABG. It seems that the measurement of QT dispersion during ET can be helpful in distinguishing patients with a recurrence of ischemia.
The dynamic development of interventional cardiology resulted in an increasing proportion of patients treated with various forms of coronary angioplasty instead of surgery. On the other hand, it has ...been well established that the results of coronary artery by-pass surgery of the left anterior descending (LAD) coronary artery with the use of the internal mammary artery are excellent.
To compare the results of primary direct stenting (PDS) and endoscopic atraumatic coronary artery bypass (EACAB) surgery in patients with an isolated proximal LAD type A or B1 lesion.
This prospective and randomised study included 100 patients with an isolated critical (> or =70%) LAD stenosis who underwent PDS (n=50) or EACAB (n=50).
After a six-month follow-up period, 32 (64%) PDS patients and 47 (94%) EACAB patients were angina-free. The rate of major cardiac adverse events (MACE) was significantly higher in the PDS group than in surgically treated patients (p<0.05). After one year of follow-up, 40 (80%) PDS-treated patients and all 50 EACAB patients had no recurrences of angina. After two-year follow-period, the survival rate without MACE was significantly higher in the EACAB group than in the PDS-treated patients (94% vs 76%, p<0.05).
Minimally invasive cardiac surgery is an alternative method to direct stenting in the treatment of patients with proximal LAD stenosis.
Prognostic significance of clinical and non-invasive risk markers in patients after surgical revascularisation remains unclear, especially in post-infarction patients with left ventricular (LV) ...dysfunction.
The single-centre, prospective study was designed to assess survival and the predictive power of several clinical and non- -invasive risk markers of all-cause (ACM) and cardiovascular mortality (CVM) in post-CABG patients with LV dysfunction.
A cohort of 61 patients (age 59+/-9 years, 49 males, LVEF 33+/-6%) 6-12 months after CABG was prospectively followed for a median of 46 months. Demographics, clinical data, medication, LVEF, QRS>120 ms or late potentials (LP) presence, QT dispersion ł80 ms, premature ventricular contractions (PVC) ł10/h, non-sustained ventricular tachycardia (nsVT), and SDNN Ł70 ms in ambulatory ECG were analysed. The ACM and CVM were evaluated. The prognostic value of analysing parameters was determined.
Fourteen patients died, 10 of them due to cardiovascular causes. Univariate Cox analysis showed that incomplete revascularisation, history of angina, heart failure, low LVEF, use of nitrates, digitalis or diuretics, and presence of LP or prolongation of QRS complex were predictors of poor outcome. Combination of angina and low LVEF was the best model in a multivariable Cox analysies for the prediction of both types of death.
The present study showed that in post-CABG patients with LV dysfunction, angina class and low LVEF are the main predictors of ACM and CVM. Combination of LVEF <30% with the presence of QRS >120 ms or LP may also be helpful in the identification of high-risk subjects. Other common non-invasive risk markers, particularly arrhythmic and autonomic, seem to lose some of their predictive power in patients after CABG and receiving beta-blocking agents.
The reduction of defibrillation threshold (DFT) in patients treated with an implantable cardioverter-defibrillator increases patients' safety and prolongs ICD battery life.
To evaluate the ...possibility of reducing the defibrillation threshold in ICDs with an active can and an additional atrial defibrillation coil instead of the typical intracardiac single-coil lead.
This study involved 138 patients (36 F and 102 M, mean age 54+/-15 years) including 62 subjects with dual-coil defibrillation lead (group A) and 76 ones with single-coil defibrillation lead (group B). No statistically significant differences with respect to age, left ventricular function, main disease or exacerbation of heart failure according to the NYHA functional class were observed between groups. The defibrillation threshold was measured using the DFT+ protocol.
No significant differences between groups were identified with respect to pacing and sensing parameters. The comparison of DFT values between the two studied groups revealed significant improvement (by 14% mean) of defibrillation efficacy in group A. In group A, the mean DFT was 9.8+/-4.6 J (3-20 J) and mean defibrillation resistance - 45+/-7 W (32-73 W), whereas in group B: 11.45+/-5.25 J (3-28 J) and 72+/-12.8 W (38-106 W), respectively. In 93% of patients from group A, DFT was below 15 J, in comparison to 81% of patients from group B (p=0.046). The odds ratio of a higher defibrillation threshold (ł15 J) in group A vs. group B was 0.3 (95% confidence interval: 0.09-0.98). The DFT reduction associated with modified ICD system use was independent of following clinical parameters: patient age, gender, main disease, end-diastolic left ventricular diameter, left ventricular ejection fraction, NYHA functional class and concomitant treatment with antiarrhythmic agents.
Modification of the electric field during defibrillation, achieved with the use of active-can ICDs with dual-coil defibrillation leads, allows a reduction of DFT by 14%. At the same time, it reduces the risk of a higher (> or =15 J) DFT by three times compared to patients with a standard single-coil defibrillation lead.
Electroanatomical mapping allows differentiation between viable and scarred myocardium. Echocardiography is widely used to assess myocardial contractility. The relationship between ...electrophysiological and echocardiographic assessment of left ventricular function has not yet been well established.
To correlate mechanical and electrical function of the left ventricle in patients with postinfarction ventricular tachycardia and to assess clinical, echocardiographic and angiographic parameters affecting regional electrical function.
In 32 patients (25 males, 64+/-9 years old) mean unipolar (UP) and bipolar (BP) voltages were obtained with electroanatomical mapping (CARTO system) for a 12-segment model and compared with segmental wall motion function scored as normal, hypokinetic and a- or dyskinetic. UP voltage in individual groups of segments was: 7.8+/-4.2 mV, 6.5+/-4.2 mV, 4.7+/-2.5 mV, p <0.01 and for BP voltage 2.1+/-1.5 mV, 1.9+/-1.9 mV, 1.1+/-1.0 mV, p < 0.01, respectively. Left ventricular ejection fraction < or =30%, end-diastolic diameter >56 mm, previous inferior or anterior myocardial infarction (MI), MI < or =5 years and open infarct-related artery were associated with lower voltage in normokinetic segments.
Segments with advanced systolic dysfunction had significantly lower uni- and bipolar voltage than normo- and hypokinetic segments. However, preserved local electrical function could be found in a/dyskinetic regions. Left ventricular remodelling, time and location of MI and patency of infarct-related artery influenced voltage in normokinetic segments.
Despite successful reperfusion therapy of acute myocardial infarction and complete restoration of infarct-related artery patency, the improvement of systolic function in long-term outcome depends on ...preserved microvasculature integrity. Myocardial contrast echocardiography (MCE) is a useful technique for identification of viable myocardium.
To assess the value of real-time myocardial contrast echocardiography (rt-MCE) in prediction of left ventricular function improvement in patients with anterior wall acute myocardial infarction as well as selection of the optimal cut-off value for the number of dysfunctional segments with preserved complete perfusion, in order to predict the global left ventricular function improvement during one-month observation.
Rt-MCE was performed in 74 patients (50 men, aged 58+/-11 years) with anterior wall myocardial infarction, treated with primary percutaneous coronary intervention (PCI) within 12 hours from the onset of symptoms. After estimation of regional contractility disturbances and global systolic function of the left ventricle, rt-MCE was performed with contrast assessment of dysfunctional segments (normal contrast pattern=2, heterogeneous=1, lack of contrast=0). Regional perfusion score index (RPSI) was calculated by adding the perfusion indices and dividing by the number of dysfunctional segments.
Of a total of 1184 visualised segments, 344 (29.1%) were dysfunctional (189 hypokinetic, 155 akinetic). Contractility improvement was observed in 192 segments (preserved viability in 105 hypokinetic and 37 akinetic segments). In a group of 44 patients with systolic function improvement, 34 of them had preserved viability, and in a group of 30 patients without LVEF improvement, in 22 of them myocardium viability was not observed. Sensitivity, specificity and accuracy of rt-MCE in prediction of left ventricular global improvement were 72.7%, 73.3% and 73%, respectively, whereas in prediction of regional function improvement these values were 73.9%, 77% and 75.5%, respectively.
Rt-MCE performed in the early phase of myocardial infarction enables the prediction of left ventricular regional and global function improvement in patients treated with primary PCI.
The prognostic significance of arrhythmogenic response to an antiarrhythmic drug was studied. In 782 patients with ischemic heart disease (IHD) and frequent and/or complex ventricular premature beats ...(VPBs), 1,041 drug tests guided by 24-hour Holter monitoring were conducted. The following drugs were assessed: beta blockers, disopyramide, mexiletine, amiodarone. Proarrhythmia was defined as: (1) greater than 4-fold increase in VPBs, (2) greater than 10-fold increase in repetitive forms, or (3) new occurrence of ventricular tachycardia or ventricular fibrillation (VT/VF). During a follow-up of 1-49 months (mean 22) patients were treated with antiarrhythmic drugs found to be safe in control Holter monitoring. Proarrhythmic effects were observed in 8.4% of patients. No drug was completely free of this type of reaction. In long-term observation, cardiac death and sudden death occurred in 53 and 32 patients, respectively. With actuarial analysis (Kaplan-Meier method, log-rank test) there was a significant difference in cardiac death (P less than 0.01) and sudden death rate (P less than 0.05) of proarrhythmia (+) compared with proarrhythmia (-) patients at 1 year (11% vs 4%, 7% vs 3%) and 3 years (24% vs 11%, 16% vs 7%). Proarrhythmic response was an independent risk factor apart from myocardial infarction, VT/VF, ejection fraction less than 40% and QTc greater than 440 msec. Arrhythmogenic response to antiarrhythmic drugs seems to be an additional predictor of sudden death in IHD.
