Optimal ECG Lead System for Exercise Assessment of Ischemic Heart Disease.

The diagnostic value of an ECG exercise test in diagnosis of ischemic heart disease (IHD) is limited. We investigated whether it is possible to develop a method for diagnosis of IHD which uses a low number of optimal ECG leads and has a higher diagnostic efficiency than conventional exercise ECG. This study was carried out on 43 patients. The 67-lead high-resolution ECG was recorded at rest and during exercise. The diagnostic value of ST segment depression (ΔST60) and T-wave morphology change (δT) determined in optimized ECG lead configurations was higher than for the standard 12-lead ECG. The best results were obtained for δT determined from 6 ECG electrode locations where sensitivity and specificity were 70% and 69% whereas for the standard exercise ECG were 63% and 62%, respectively. The small number of ECG leads used allows for easy hardware implementation of the methods for use in clinical settings.

High-Resolution Body Surface Potential Mapping in Exercise Assessment of Ischemic Heart Disease.

Standard 12-lead ECG exercise testing is commonly used for screening of ischemic heart disease (IHD). We studied if high-resolution body surface potential mapping (HR-BSPM) during exercise offers advantages over current standards in noninvasive evaluation of IHD. This study was carried out on 90 IHD patients and 33 healthy controls. The 67-lead HR-BSPM was recorded at rest and during exercise. Twenty-one ECG parameters including classical ST criteria were compared. The effectiveness of methods was verified based on the results of SPECT and coronary angiography. The most effective parameters in the diagnosis of IHD were: amplitude parameter ΔST60 and δT parameter showing T-wave morphology changes during exercise. The sensitivities/specificities of ΔST60 and δT parameters for the HR-BSPM were 70/69 and 59/62%, while for the standard 12-lead ECG system they were: 63/62 and 59/56%. These results demonstrate the usefulness of HR-BSPM measurements during exercise. HR-BSPM resulted in higher sensitivities and specificities compared to the standard 12-lead exercise test. The advantage was partially associated with observed ischemic changes outside standard precordial leads position that were not visible when using the standard 12-lead exercise test. This justifies research into the optimization of the number and position of ECG leads in exercise testing.

Evaluation of T-wave alternans in high-resolution ECG maps recorded during the stress test in patients after myocardial infarction.

INTRODUCTION: Recent studies point to analysis of T-wave alternans as a promising indicator of an increased risk of life-threatening ventricular arrhythmias. In this study the occurrence of T-wave alternans in the high-resolution ECGs recorded during the exercise stress test and scintigraphic tests (SPECT) in patients with ischemic heart disease was examined. MATERIAL AND METHODS: The study group consisted of 33 patients after myocardial infarction. In the group of patients after myocardial infarction and with low left ventricular ejection fraction correlations of 70% between the test results of T-wave alternans and SPECT and 60% between the test results of T-wave alternans and stress test were found. RESULTS: In the group of patients after myocardial infarction but with high left ventricular ejection fraction correlations were respectively 39% and 48%. The analysis of the electrocardiographic maps showed a strong dependence of this correlation on the T-wave alternans amplitude and location of the ECG measuring electrode on the chest. The results might suggest that in patients after myocardial infarction and at increased risk for sudden cardiac death T-wave alternans may also provide information about cardiac electrical instability associated with ischemia. CONCLUSIONS: It can also be assumed that the position of the electrode where the highest level of the T-wave alternans was detected can indicate the location of the ischemic region of the heart.

ST-segment changes in high-resolution body surface potential maps measured during exercise to assess myocardial ischemia: a pilot study.

INTRODUCTION: The aim of the study was to assess myocardial ischemia by analysis of ST-segment changes in high-resolution body surface potential maps (HR-BSPM) measured at rest and during an exercise stress test. MATERIAL AND METHODS: The study was carried out on a group of 28 patients with stable coronary artery disease and 15 healthy volunteers. The HR-BSPM were measured at rest and during the exercise stress test on a supine ergometer. The workload was increased in stages by 25 W every 2 min, beginning at 50 W. The maps of ST-segment depression (ST60) were calculated from time averaged recordings at rest and at maximal workload. RESULTS: The efficiency in detection of myocardial ischemia was higher for HR-BSPM than for standard 12-lead electrocardiography (ECG) when both methods were evaluated by outcomes of coronarography. The sensitivity of HR-BSPM was 82.4% while for the standard 12-lead ECG exercise stress test it was 58.8%. For some patients significant changes in the ST segment were observed at stress HR-BSPM but were not visible in standard 12-lead ECG recorded under the same conditions. CONCLUSIONS: Obtained high values of sensitivity and specificity in myocardial ischemia detection suggest that maps of ST60 calculated from HR-BSPM can improve detection of patients with ischemic heart disease in comparison to the standard electrocardiographic exercise stress test examinations.

The effect of cycle ergometer exercise training on improvement of exercise capacity in patients after myocardial infarction.

BACKGROUND: Cardiac rehabilitation in patients after myocardial infarction (MI) is a component of secondary prevention that has an established role in the current guidelines. AIM: To determine the effect of physical training on exercise capacity parameters determined on the basis of cardiopulmonary exercise test (CPET) in patients after MI. We also evaluated the relationship between the number of training sessions and exercise capacity. METHODS: We prospectively evaluated 52 patients after MI who underwent percutaneous coronary intervention of the infarct-related artery. At the start of the training, patients had no symptoms of heart failure and coronary artery disease. Electrocardiographic exercise test was performed 4 to 6 weeks after MI, followed by CPET in patients with a negative stress test. After determination of the initial exercise capacity, patients underwent 12 training sessions on a cycle ergometer with a workload determined on the basis of anaerobic threshold or heart rate reserve. After 12 training sessions, CPET was performed, followed by another 12 training sessions and a follow-up CPET. RESULTS: All patients showed a significant increase in exercise capacity parameters: energy expenditure during CPET increased from 9.39 to 11.79 METs, peak oxygen uptake (VO2peak) increased from 32.32 to 39.25 mL/kg/min (p < 0.001), and oxygen uptake at the anaerobic threshold increased from 18.34 to 24.65 mL/kg min (p < 0.001). The initial 12 training sessions resulted in a statistically significant increase in VO2peak from 32.32 to 36.75 mL/kg/min (p = 0.003), while subsequent 12 training sessions were related with an insignificant increase in VO2peak from 36.75 to 39.25 mL/kg/min (p = 0.065). CONCLUSIONS: Regular physical activity improves exercise capacity as measured by CPET. A statistically significant improvement in exercise capacity was seen already after initial 12 training sessions, while another 12 training sessions were associated with smaller benefits.

Radiofrequency ablation without the use of fluoroscopy - in what kind of patients is it feasible?

INTRODUCTION: The aim of the study was to describe the experience in performing ablation without fluoroscopy. MATERIAL AND METHODS: From 575 ablation procedures with CARTO performed in the period 2003-2008, 108 (42 M; age 40 ±16 years) were done without fluoroscopy. One patient had ablation using the Localisa system. There was one man with thrombocytopenia and two pregnant women. RESULTS: Right ventricular (RV) outflow tract arrhythmias and other RV arrhythmias were noted in 38 patients (35%) and 17 patients (15%), respectively. There were 5 (4.6%) left ventricular (LV) outflow tract arrhythmias and 19 (17.5%) other LV tachycardias; right accessory pathways in 17 patients (20%), in the middle cardiac vein in 1, Mahaim fibres in 1, and 3 cases of permanent junctional reciprocating tachycardias. One patient with CRT had AV node ablation (Localisa). In 3 patients there were also other arrhythmias treated: slow AV nodal pathway, typical flutter isthmus and right atrial tachycardia. In 2004, 1/96 CARTO procedures was done without fluoroscopy, in 2006 2/97, in 2007 19 (2 in LV) of 93, in 2008 87 (22 in LV) of 204. The percentage of ablations without fluoroscopy in every hundred CARTO procedures was: 1%, 1%, 8%, 23%, 46%, 28% (mean 18%). There were no procedure-related complications. CONCLUSIONS: It is feasible to perform ablations within both right and left sides of the heart without fluoroscopy. The number and type of non-fluoroscopic procedures depends on the operator's experience. Pregnant patients, with malignant history or with hematologic diseases should be ablated without fluoroscopy in centres that specialise in these kinds of procedures.