Predictive accuracy of tissue Doppler imaging for assessment of noninfarct myocardial region in patients with acute myocardial infarction

To investigate the value of pulsed tissue Doppler imaging [TDI] in order to predict significant coronary artery stenosis supplying the noninfarct region in patients after acute anterior myocardial infarction. Transthoracic echocardiography and coronary angiography were performed on 220 patients with acute anterior myocardial infarction. The TDI-derived variables of the mitral valve annulus in the noninfarct region, systolic velocity [Sm], early diastolic velocity [Em] and late diastolic velocity [Am], were estimated in centimeters per second, and the Em/Am ratio was calculated. Predictive indices revealed that the impaired TDI-derived variables, Sm, Em, Am and the Em/Am ratio, were an indicator for predicting significant coronary stenosis in the noninfarct region. Multivariate analysis revealed that the impaired Sm and Em velocities were significantly associated with age of the patients, coronary collaterals and infarct-related artery stenosis [p < 0.05]. Receiver-operating characteristic curve data of TDI-derived variables for prediction of significant coronary stenosis revealed that the cut-off values of Sm, Em, Am and Em/Am ratio were 7.2 cm/s, 6.4 cm/s, 12.1 cm/s and 0.56, respectively. The K coefficient value indicated that there was an agreement between coronary angiography and the TDI-derived variables Sm, Em, Am and Em/Am ratio in noninfarct regions [K = 0.770, 0.731, 0.693 and 0.679, respectively]. There was a significant correlation between the severity of coronary artery stenosis [independent variable] and impaired Sm and Em/Am ratio [dependent variables], y = 11.5 - 0.05x, r = -0.902, [p < 0.05], and y = - 0.14x + 1.87, r = -0.754, [p < 0.05], respectively. TDI can be used to identify patients with significant stenosis of the coronary arteries supplying the noninfarct region and consequently may be helpful in considering patients for coronary angiography in the early postinfarction period

Utility of exercise electrocardiographic stress test for assessment of cardiac autonomic function in hypertensive patients

To evaluate the usefulness of recovery time after a treadmill exercise ECG test for assessment of autonomic function in hypertensive patients using Holter-based heart rate variability as a reference. One hundred untreated hypertensive patients were included in the study. Echocardiography was done to assess left ventricular mass index and function. Exercise ECG test was done in all patients. The heart rate recovery was calculated as the reduction in heart rate from its peak value to one minute of the recovery time. A cut off value of 12 beats/minute or less was considered abnormal. The patients were classified into two groups; Group I: included 70 patients with impaired heart rate variability and Group II: included 30 patients with normal heart rate variability. Holter 24 - hour ECG monitoring was done in all patients for assessment of heart rate variability. There was a significant impaired heart rate variability in hypertensive patients, with impaired heart rate recovery than in those with normal heart rate recovery [p<0.05]. Predictive indices of heart rate recovery after exercise ECG test, for assessment of cardiac autonomic function revealed a sensitivity of 74%, specificity of 83.3%, positive predictive value of 91.5%, negative predictive value of 58.2% and an accuracy of 77%. Stepwise logistic analysis revealed a significant relation between the maximal heart rate during exercise test, time-domain heart rate variability variables [r-MSSD and p-NN50] and impaired heart rate recovery after exercise ECG test in hypertensive patients [p<0.05].There was a significant correlation between Holter based vagal dependent r-MSSD and the heart rate recovery after exercise test [p<0.05]. Incorporation of heart rate recovery after e x e rcise may eventually be considered an useful diagnostic test for assessment of autonomic nervous system function in hypertensive patients

QT dispersion Immediately after exercise test improves sensitivity and specificity for diagnosis of ischemic heart disease

To evaluate the validity of QT-dispersion immediately after a treadmill exercise electrocardiography [ECG] test for diagnosis of ischemic heart disease in the presence or absence of exercise induced significant ST-segment depression. We studied 80 patients [70 men and 10 women] without history of myocardial infarction [MI]. All patients underwent treadmill exercise ECG test and coronary angiography. The patients were classified into two groups: Group I: included 30 patients with normal coronary angiography and Group II: included 50 patients with angiographically documented coronary artery disease [CAD]. There was a significant increased QT dispersion [p < 0.05] immediately after exercise and a significant ST segment depression [p < 0.05] in patients with CAD than those with normal coronary artery, but no significant difference at baseline and after six minutes during recovery [p = NS]. Predictive indices revealed that QT dispersion immediately after exercise was a valid indicator for prediction of ischemic heart disease. Its sensitivity was 80%, specificity 83%, accuracy 81%, positive predictive value 88% and negative predictive value 71%. There was a significant correlation between coronary artery stenosis and QT dispersion immediately after exercise [r = 0.786 and p < 0.01] and QT dispersion [60 ms] corresponded to coronary artery stenosis [70%] in patients with single vessel disease. There was a good agreement between two observers and no significant difference as regards intraobserver and interobserver variability. Stepwise logistic multivariate analysis revealed a significant relation between hypertension status, left ventricular hypertrophy and increased QT dispersion immediately after exercise test in patients with CAD [p < 0.05]. QT dispersion, immediately after exercise is a clinically useful marker of exercise induced myocardial ischemia independent of the presence or absence of exercise-induced significant ST-segment depression

Utility of transtelephonic electrocardiographic Transmission system for detection of ischemic ST-segment during exercise stress test

To confirm or deny the hypothesis that the transtelephonic electrocardiographic [ECG] transmission system is useful for the detection of ischemic ST-segment during exercise in patients with typical chest pain. Prospective clinical study. Non-invasive Cardiac Unit, Department of Medicine, Farwania Hospital, Kuwait. One hundred patients with chest pain were included in the study but only 60 were patients with angiography documented coronary artery disease. All the patients underwent treadmill exercise ECG test. Transtelephonic ECG transmission system was provided for all the patients during their exercise ECG test. Simultaneous transtelephonic recording yielded 15 out of the 35 patients with a ST segment depression at peak exercise [sensitivity = 42%]. Out of 60 patients with a negative ST segment response to exercise test, only five patients [false positive] had a 1 mm ST segment depression detected on transtelephonic system [specificity = 92%]. There were 20 false negative transmissions on transtelephonic recorder when the ST segment response to exercise test was positive. But in the patient group that underwent coronary angiography, there was an increase in sensitivity [60%] and specificity [100%] of transtelephonic re c o rder in detecting the ischemic ST segment, as there were no false positive results. With regard to detection of ventricular arrhythmias, the transtelephonic system had 100% sensitivity and specificity. Stepwise logistic analysis showed no significant relation to age, gender, body mass index, history of myocardial infarction, diabetes mellitus status and hypertension as independent variables [p = NS]. Transtelephonic system tended to underestimate the peak amplitude of the ST segment depression as compared to the maximal ST segment depression observed during exercise test [1.22 +/- 0.21 versus 1.81 +/- 0.43 mm, p<0.05]. There was no significant correlation between ST segment depression observed by exercise test and transtelephonic system [r = 0.582, p = NS]. Despite the limitations and the confounders of our approach, this study suggests a limited value of this small monitor for the outpatients awaiting episodes of chest pain. Further studies are needed to clarify the validity and reliability of this diagnostic tool in these clinical settings

Heart rate variability in hypertensive patients with left ventricular diastolic dysfunction

This study aimed to evaluate the role of autonomic nervous system in determining the appearance of diastolic ventricular dysfunction in patients with previously unrecognized and untreated essential hypertension. Sixty middle aged and pharmacologically untreated hypertensive subjects [45 men and 15 women] and 30 normotensive subjects [24 men and 6 women] as a control group [group I] were studied. All patients were referred from outpatient clinic with blood pressure morethan 140/90 mmHg as detected by ambulatory blood pressure monitoring with an auscultatory device. Echocardiography was done to assess left ventricular diastolic function. Exercise ECG test was done to exclude patients with ischaemic heart disease. Holter ECG monitor was done for all subjects to assess heart rate variability. Hypertensive patients were classified into two groups: Group II included 30 patients with diastolic dysfunction and group III included 30 patients with normal ventricular systolic function. In regard of age, gender, left ventricular mass index and left ventricular systolic function, there was no significant difference between all the groups of study; but the hypertensive patients of group II had a significant decreased E/A ratio, a significant decreased r-MSSD and p-NN50 and a significant increased daytime and nighttime heart rate than subjects and patients of groups I and II. There was a significant correlation between vagal dependent parameter [r-MSSD] and E/A ratio. Stepwise logistic analysis revealed that there was no significant relation between age, gender and ambulatory systolic and diastolic blood pressure and the presence of left ventricular diastolic dysfunction in hypertensive patients. It was concluded that left ventricular diastolic dysfunction in hypertensive patients without left ventricle hypertrophy is related to reduced parasympathetic activity and this supports the use of non-pharmacologic treatments that increase vagal tone