Comparison of diagnostic accuracy, time dependency, and prognostic impact of abnormal Q waves, combined electrocardiographic criteria, and ST segment abnormalities in right ventricular infarction.

OBJECTIVE--To determine the diagnostic and prognostic impact of abnormal Q waves in comparison to or in combination with ST segment abnormalities in the right precordial and inferior leads as indicators of right ventricular infarction during the acute phase of inferior myocardial infarction. DESIGN--Prospective study of a consecutive series of 200 patients with acute inferior myocardial infarction with and without right ventricular infarction. SETTING--Department of internal medicine, university clinic. RESULTS--Right ventricular infarction was diagnosed in 106 (57%) out of 187 patients from the results of coronary angiography, technetium pyrophosphate scanning, and measurement of haemodynamic variables or at necropsy, or both. In the acute phase of inferior infarction ST segment elevation > or = 0.1 mV in any of the right precordial leads V4-6R was the most reliable criterion for right ventricular infarction (sensitivity, 89%; specificity, 83%). Abnormal Q waves in the right precordial leads, the most specific criterion (91%) for right ventricular infarction, were superior to ST segment elevation in patients admitted > 12 hours after the onset of symptoms. Both ST segment elevation in leads V4-6R (increase in in hospital mortality, 6.2-times; P < 0.001; major complications, 2.3-times; P < 0.01) and abnormal Q waves (2.3-times, P < 0.05; 1.8-times, P < 0.05) on admission were highly predictive of a worse outcome during the in hospital period. In the presence of inferior myocardial infarction previously proposed combined electrocardiographic criteria were not better diagnostically or prognostically than ST segment abnormalities and abnormal Q waves alone. CONCLUSIONS--During the first 24 hours of inferior myocardial infarction ST segment elevation and abnormal Q waves derived from the right precordial leads are complementary rather than competitive criteria for reliably diagnosing right ventricular infarction, both indicating a worse in hospital course for the patient. In this they are better than any other previously proposed combined electrocardiographic criteria in diagnosing right ventricular infarction. Right precordial leads should be routinely monitored in acute inferior myocardial infarction.     

Effects of abnormal activation on the time course of the left ventricular pressure pulse in dilated cardiomyopathy.

OBJECTIVE--To investigate the effects of QRS duration on characteristics of the left ventricular pressure pulse derived from the time course of functional mitral regurgitation by continuous wave Doppler. DESIGN--Retrospective and prospective study of 50 patients with dilated cardiomyopathy, by electrocardiography, echocardiography, and Doppler cardiography. SETTING--Tertiary cardiac referral centre. PATIENTS--50 patients (mean age (SD) 58 (16)) with dilated cardiomyopathy, all with functional mitral regurgitation. RESULTS--The values of QRS duration ranged widely, from 70 to 190 ms with a mean value of 110 ms, and were unimodally distributed. The overall duration of mitral regurgitation correlated positively with QRS time (r = 0.65) over the entire range of values. When the duration of mitral regurgitation was divided into contraction, aortic ejection, and relaxation times, increased QRS duration prolonged contraction (r = 0.51) and relaxation (r = 0.52) times. Aortic ejection time was affected by RR interval (r = 0.74). Duration of QRS correlated negatively with peak rate of rise in left ventricular pressure (+dP/dt) (r = -0.48), and positively with the time intervals from Q to peak pressure (r = 0.49) and to peak +dP/dt (r = 0.72), and also with those from the start of mitral regurgitation to peak pressure (r = 0.49) and to peak +dP/dt (r = 0.76). Duration of QRS did not directly affect the peak rate of left ventricular pressure fall (-dP/dt), or the isovolumic relaxation period. CONCLUSIONS--Values of QRS duration are unimodally distributed in patients with dilated cardiomyopathy, without evidence of a discrete group of patients with left bundle branch block. Prolonged QRS duration reduces peak +dP/dt, prolongs overall duration of the pressure pulse, the time to peak +dP/dt, and relaxation time. Duration of QRS must therefore be taken into account in assessing standard measurements of myocardial function in patients with dilated cardiomyopathy.     

Effects of abnormal activation on the time course of the left ventricular pressure pulse in dilated cardiomyopathy

Objective—To investigate the effects of QRS duration on characteristics of the left ventricular pressure pulse derived from the time course of functional mitral regurgitation by continuous wave Doppler.Design—Retrospective and prospective study of 50 patients with dilated cardiomyopathy, by electrocardiography, echocardiography, and Doppler cardiography.Setting—Tertiary cardiac referral centre.Patients—50 patients (mean age (SD) 58 (16)) with dilated cardiomyopathy, all with functional mitral regurgitation.Results—The values of QRS duration ranged widely, from 70 to 190 ms with a mean value of 110 ms, and were unimodally distributed. The overall duration of mitral regurgitation correlated positively with QRS time (r=0·65) over the entire range of values. When the duration of mitral regurgitation was divided into contraction, aortic ejection, and relaxation times, increased QRS duration prolonged contraction (r=0·51) and relaxation (r=0·52) times. Aortic ejection time was affected by RR interval (r=0·74). Duration of QRS correlated negatively with peak rate of rise in left ventricular pressure (+dP/dt) (r=−0·48), and positively with the time intervals from Q to peak pressure (r=0·49) and to peak +dP/dt (r=0·72), and also with those from the start of mitral regurgitation to peak pressure (r=0·49) and to peak +dP/dt (r=0·76). Duration of QRS did not directly affect the peak rate of left ventricular pressure fall (−dP/dt), or the isovolumic relaxation period.Conclusions—Values of QRS duration are unimodally distributed in patients with dilated cardiomyopathy, without evidence of a discrete group of patients with left bundle branch block. Prolonged QRS duration reduces peak +dP/dt, prolongs overall duration of the pressure pulse, the time to peak +dP/dt, and relaxation time. Duration of QRS must therefore be taken into account in assessing standard measurements of myocardial function in patients with dilated cardiomyopathy.     

Effects of abnormal activation on the time course of the left ventricular pressure pulse in dilated cardiomyopathy

Objective—To investigate the effects of QRS duration on characteristics of the left ventricular pressure pulse derived from the time course of functional mitral regurgitation by continuous wave Doppler.

Design—Retrospective and prospective study of 50 patients with dilated cardiomyopathy, by electrocardiography, echocardiography, and Doppler cardiography.

Setting—Tertiary cardiac referral centre.

Patients—50 patients (mean age (SD) 58 (16)) with dilated cardiomyopathy, all with functional mitral regurgitation.

Results—The values of QRS duration ranged widely, from 70 to 190 ms with a mean value of 110 ms, and were unimodally distributed. The overall duration of mitral regurgitation correlated positively with QRS time (r=0·65) over the entire range of values. When the duration of mitral regurgitation was divided into contraction, aortic ejection, and relaxation times, increased QRS duration prolonged contraction (r=0·51) and relaxation (r=0·52) times. Aortic ejection time was affected by RR interval (r=0·74). Duration of QRS correlated negatively with peak rate of rise in left ventricular pressure (+dP/dt) (r=−0·48), and positively with the time intervals from Q to peak pressure (r=0·49) and to peak +dP/dt (r=0·72), and also with those from the start of mitral regurgitation to peak pressure (r=0·49) and to peak +dP/dt (r=0·76). Duration of QRS did not directly affect the peak rate of left ventricular pressure fall (−dP/dt), or the isovolumic relaxation period.

Conclusions—Values of QRS duration are unimodally distributed in patients with dilated cardiomyopathy, without evidence of a discrete group of patients with left bundle branch block. Prolonged QRS duration reduces peak +dP/dt, prolongs overall duration of the pressure pulse, the time to peak +dP/dt, and relaxation time. Duration of QRS must therefore be taken into account in assessing standard measurements of myocardial function in patients with dilated cardiomyopathy.

     

The stability of the ST segment estimation of myocardial area at risk between the prehospital and hospital electrocardiograms in patients with ST elevation myocardial infarction

Purpose

Several ST segment deviation scores have been developed to estimate the myocardial area at risk (AAR) during acute myocardial infarction (AMI), which can be used to measure the effectiveness of reperfusion therapy. The purpose of this study was to assess whether one of these ST segment deviation scores (the Aldrich score) is sufficiently stable between the electrocardiogram (ECG) recorded in the ambulance (ECG 1) and the ECG recorded at the time of admission to the hospital (ECG 2) to be used as a baseline estimation of the AAR.

Methods

The Aldrich scores were compared between ECG 1 and ECG 2 in 77 patients who met the criteria for ST elevation myocardial infarction. The ECGs had a time interval of at least 5 minutes and were recorded before reperfusion therapy. Sufficiently stable was defined as 95% of the patients did not show a temporal change of the Aldrich score of more than 4.5%.

Results

The mean time interval between ECG 1 and ECG 2 was 20 ± 9 minutes. Forty-three percent of the total study population showed an “unstable Aldrich score” between ECG 1 and ECG 2. Fifty-seven percent showed a “stable Aldrich score”, which means that the 95% standard for sufficiently stable was not fulfilled. By dividing the population based on infarct location, the group with inferior AMI (n = 43) showed more stability (67%) than the group with anterior AMI (n = 34) (44%) (P < .05). However, this remains less than the 95% stability standard.

Conclusion

For both inferior and anterior AMI locations, the Aldrich score was not sufficiently stable to be used as a reliable baseline estimation of the AAR in AMI.     

Noninvasive evaluation of the time course of change in cardiac function in spontaneously hypertensive rats by echocardiography.

The spontaneously hypertensive rat (SHR) has been well established as a suitable model for studies of hypertension, but little is known about the processes of left ventricular (LV) hypertrophy and the changes in cardiac function in this model. The present study was designed to provide a noninvasive evaluation of the time-dependent alteration of cardiac function in male SHR at 4 to 24 weeks of age and age-matched Wistar-Kyoto rats (WKY). Echocardiographic studies were performed after blood pressure (BP) and heart rate (HR) were measured by a tail-cuff method. The body weight (BW) of SHR was lighter than that of WKY at all ages, and HR was consistently lower, with significantly elevated systolic BP from 4 weeks of age. In the echocardiographic study, LV mass at 4 weeks of age was similar between WKY and SHR, although the ratio of LV mass to BW was higher in SHR than WKY. The ejection fraction, fractional shortening (FS) and midwall FS did not differ between the two groups at 4 weeks, but after 8 weeks, these parameters were decreased in the SHR. The deceleration time was prolonged in SHR after 16 weeks and the E/A ratio was lowered at 12 weeks. We also analyzed the expression levels of calcineurin, which were found to be increased in both groups with age. These results suggest that calcineurin does not play a major role in the development of LV hypertrophy. Thus, in SHR, cardiac hypertrophy develops by 4 weeks of age, and systolic and diastolic dysfunction is evident at 2 to 3 months.     

Continuous vectorcardiography in acute myocardial infarction. Natural course of ST and QRS vectors

We made continuous recordings of the X, Y and Z Frank leads in 43 patients with their first myocardial infarction admitted within 4 hours of the onset of pain. Sequential hourly analysis of the ST and QRS vector changes during the first 24 hours was performed. In short-term survivors (n = 38) mean serial changes of ST vectors showed an initial rapid decline until the 8th-10th hour, whereas QRS vector changes lasted longer and were completed within 13.5 +/- 3.6 hours (inferior infarction) and 10.2 +/- 2.4 hours (anterior infarction) respectively. The initial ST vector magnitude was significantly correlated to the subsequent cumulative QRS vector change (r = 0.82). The individual ST vector changes showed a rapid decline in 33 of 38 patients (87%), whereas in 5 patients the ST vector magnitude increased to reach its maximum after 4-6 hours. After the initial decline new increases of the ST vector magnitude was noted in 16 patients on 20 occasions. In 13 instances this was associated with recurrent pain. The spatial change of ST vector direction with reference to the initial direction was significantly greater when recurrent ST rises were accompanied by additional QRS vector changes, compared to those without associated QRS changes (P less than 0.025). The individual QRS vector slopes could be characterized as (1) monophasic (n = 21, 55%), (2) polyphasic (n = 11, 29%) and (3) irregular (n = 6, 16%). We conclude that continuous vectorcardiography is a suitable method for following ST and QRS vector changes that accompany acute myocardial infarction and that ST vector changes can be used to predict subsequent QRS vector changes.     

Effects of recent and remote infarction on the predictive accuracy of the ST segment/heart rate slope

The exercise electrocardiographic ST segment/heart rate slope accurately identifies three vessel coronary disease in patients with stable angina, but the method is less accurate in predischarge testing after recent myocardial infarction. To assess the effect of both recent (less than 3 weeks) infarction and remote (greater than 8 weeks) Q wave infarction on the ST segment/heart rate slope, the predictive value of a slope greater than 6.0 microV/beat per min for the identification of three vessel coronary artery disease was evaluated in 113 patients. The 58 patients with stable angina, including 17 with remote Q wave myocardial infarction, were similar to the 55 patients with recent myocardial infarction with respect to age and peak exercise heart rate. In patients with stable angina and no prior Q wave myocardial infarction, an ST segment/heart rate slope greater than 6.0 had a sensitivity of 92% (11 of 12), a specificity of 97% (28 of 29) and a positive predictive value of 92% (11 of 12) for three vessel coronary artery disease. In patients with stable angina and remote Q wave infarction, sensitivity was 83% (5 of 6), specificity was 91% (10 of 11) and positive predictive value was 83% (5 of 6). After recent infarction, test specificity for three vessel disease was preserved at 95% (39 of 41), but test sensitivity was poor (3 of 8). This was confirmed by evaluation of six additional recent patients with infarction and three vessel disease. Among the combined group with recent infarction, test sensitivity for three vessel disease was only 29% (4 of 14), significantly lower than in patients with stable angina (p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Predictive value and limitations of the ST/HR slope.

To assess the value and predictive limitations of the exercise ST/HR slope, exercise test results were compared in 50 patients with stable angina and in 17 normal subjects with those in two groups known to have a high prevalence of inaccurate electrocardiographic responses to exercise. The last two groups included 51 patients tested within three weeks of acute myocardial infarction and 17 with important aortic regurgitation but no coronary disease. Of the normal subjects, 16 (94%) had ST/HR values less than or equal to 1 X 1 microV/beat/min. Of those with stable angina pectoris, 42 of 46 (91%) patients with coronary artery disease had ST/HR slopes ranging from 1 X 2 to 20 X 0 microV/beat/min, with false negative findings (slopes less than or equal to 1 X 1 microV/beat/min) in only four (9%). In contrast, of those with recent myocardial infarction, 15 of 42 (36%) with coronary disease had false negative slopes, including 12 of 20 (60%) with anterior wall injury. Of those with aortic regurgitation, conversely, 14 of 16 (88%) patients with calculable ST/HR slopes had values greater than 1 X 1 microV/beat/min despite the absence of coronary disease. Despite the accuracy of the test in patients with stable angina, false negative results are common in those after recent myocardial infarction, and false positive results occur often in those with abnormal volume loading due to aortic regurgitation.     

Pathophysiology and time course of silent myocardial ischaemia during mental stress: clinical, anatomical, and physiological correlates.

OBJECTIVE--To define the prevalence and pathophysiology of myocardial ischaemia induced by mental stress in patients with coronary artery disease and exercise inducible ischaemia, and to determine the correlation between the severity of coronary artery disease and ischaemia induced by speech. DESIGN--Prospective cohort study. SETTING--Tertiary care academic institution. PATIENTS AND PROTOCOL--47 patients with coronary artery disease and 20 normal controls were studied using standardised exercise and mental stress. The ambulatory nuclear vest provided continuous measures of left ventricular ejection fraction and relative volume changes: an ischaemic response to mental stress was defined as a decrease in ejection fraction of > or = 5% for > or = 60 s. Severity of coronary artery disease was assessed by the extent of thallium reversibility on exercise testing and the severity of angiographic disease. RESULTS--23 (49%) of 47 patients with coronary artery disease had an ischaemic response to mental stress which occurred early, was sustained throughout the task and associated with an increase in end systolic volume. In contrast, the pattern of left ventricular response in the remaining 24 patients (51%) resembled that in the normal controls. Patients with mental stress induced ischaemia tended to have greater severity of coronary disease (mean (SD) total number of diseased vessels 1.9 (0.8) v 1.4 (0.9), P = 0.07), more frequent exercise induced angina (17/23 v 7/24, P = 0.003) and lower increases in heart rate (36 (11) v 49 (23) beats per min, P = 0.023) and systolic blood pressure (32 (19) v 45 (18) mm Hg, P = 0.03) during exercise. Left ventricular responses to speech and exercise were compared in the 23 patients with mental stress induced ischaemia: mental stress was associated with a greater decrease in ejection fraction at comparable increases in rate pressure product (-6.5 (6.3)% v 4.7 (11.2)%, P = 0.0001). CONCLUSIONS--These findings suggest that mental stress induction of myocardial ischaemia is common in patients with stable coronary artery disease. Susceptible patients may have more functionally severe coronary disease. The time course, pattern, and haemodynamic features of mental stress induced ischaemia suggest a dynamic decrease in coronary supply.     

Significance of minor ST segment and T wave changes in the resting electrocardiogram of asymptomatic subjects.

Sixteen thousand resting electrocardiograms were performed on 14000 United Kingdom professional aircrew and air traffic control officers over a two-year period; 103 asymptomatic men with minor ST segment and T wave changes at rest were assessed by exercise electrocardiography and 19 responded abnormally. Five subjects had proven coronary artery disease, one hypertrophic obstructive cardiomyopathy, and one left ventricular dilatation on echocardiography. Eleven subjects were not investigated, of whom three had strongly positive exercise responses. One subject had a false positive response and assuming a false negative response of less than 2 per cent, then a sensitivity of 80.0 per cent, a specificity of 89.1 per cent, a predictive value for the exercise electrocardiogram of 44.46 per cent and for the resting electrocardiogram of 7.8 per cent is obtained. T wave changes induced by hyperventilation were common (53.4% of all). Ten (18.2%) subjects with hyperventilation-induced T wave changes responded abnormally to exercise, three having angiographically proven coronary artery disease lending little support to the contention that the two entities rarely coexist. In spite of the low return from routine electrocardiograms in a population with a low prevalence of coronary artery disease, three-eighths of those with significant coronary artery disease presented with minor ST segment and T wave changes on their resting electrocardiograms.