Reproducibility of symptom-limited exercise-stress testing performed 2 and 6 weeks after myocardial infarction.

To assess the reproducibility of variables with prognostic value from exercise testing, two symptom-limited treadmill exercise tests were performed in 76 consecutive patients at 2 weeks (predischarge) and 6 weeks after myocardial infarction. In addition, cardiac catheterization was performed at 6 weeks. Exercise duration showed a moderate increase from 7.9 +/- 4.4 min to 8.8 +/- 3.0 min (NS). The rate-pressure product increased from 22,377 +/- 5491 to 24,832 +/- 7261 (P less than 0.001). Reproducibility of ST-segment depression was dependent on the initial response: among the group of 25 patients with ST-segment depression at 2 weeks, only 13 (52%) patients had a reproducible result, whereas among the group of 51 patients without initial ST-segment depression, 40 (78%) patients showed reproducibility. There was no difference in coronary anatomy or ejection fraction between the groups with and without reproducibility results. Among the 30 patients with initial ST-segment elevation, 15 (50%) patients showed reproducibility, while among the 46 patients without initial ST-segment elevation, 42 (91%) patients showed reproducibility: the ejection fraction was significantly higher in the latter group than in the group of patients with lower reproducibility. Thus predischarge exercise testing in postinfarction patients identifies a different group of patients at risk compared to exercise testing after 6 weeks, due to considerable variation between the two tests.

Simultaneous transesophageal two-dimensional echocardiography and atrial pacing for detecting coronary artery disease.

This study describes a new technique for assessing wall motion abnormalities, combining transesophageal echocardiography (TEE) and transesophageal atrial pacing in 71 patients. Stable capture was reached in 70 patients (99%). In 3 patients (4%) pacing was discontinued prematurely because of discomfort. TEE during pacing was performed in 52 patients with and in 18 patients without coronary artery disease (CAD). In 43 of 52 patients with CAD, regional wall motion abnormalities occurred (sensitivity 83%). No wall motion abnormalities occurred in 17 of 18 patients without CAD (specificity 94%, positive predictive value 98%). Wall motion abnormalities related to another vascular region were observed in 17 of 22 patients with previous myocardial infarction (sensitivity 77%, specificity 100%, positive predictive value 100%). Simultaneous 12-lead electrocardiography during atrial pacing was performed in 57 patients and yielded positive results in 21 of 40 patients with (sensitivity 52%) and in 3 of 17 patients without (specificity 82%, positive predictive value 88%) CAD. Exercise stress testing was performed in 66 patients. Twenty-four of 48 patients with CAD had a positive exercise electrocardiogram (sensitivity 50%); a false-positive exercise electrocardiogram was observed in 3 of 18 patients (specificity 83%, positive predictive value 89%). It is concluded that TEE during transesophageal atrial pacing is a feasible and promising alternative technique for the assessment of CAD, with a higher sensitivity than simultaneous 12-lead and exercise electrocardiography.

Value of pulmonary venous flow characteristics in the assessment of severity of native mitral valve regurgitation: an angiographic correlated study.

To evaluate the relation between left ventricular angiography and pulmonary venous flow velocity in native mitral valve regurgitation, 28 patients with sinus rhythm and valvular and/or coronary artery disease underwent transesophageal echocardiography within 24 hours after cardiac catheterization. Group I consisted of 17 patients, seven patients without (grade 0) and 10 patients with angiographically mild to moderate mitral regurgitation (grades 1 and 2). Group II consisted of 11 patients with angiographically severe mitral regurgitation (grades 3 and 4). Mitral regurgitation by transesophageal echocardiography was evaluated by measuring the regurgitant jet sizes and color-guided pulsed Doppler pulmonary venous flow velocities. Multivariate analysis revealed that the most powerful predictor (p less than 0.001) of angiographically severe (grades 3 and 4) mitral regurgitation was reversed systolic flow into the left upper pulmonary vein (sensitivity 82%, specificity 100%, positive predictive value 100%). If this variable was excluded from analysis, jet area and jet length (p less than 0.001) were the next best predictors for angiographically severe mitral regurgitation. Mean values of systolic peak pulmonary venous flow velocities were significantly lower in patients from group II, 13.0 +/- 11.1 cm/s versus 43.4 +/- 20.6 cm/s (group I) with p less than 0.005. This finding was also true for systolic time velocity integral, 1.3 +/- 1.3 cm (group II) versus 7.8 +/- 5.3 cm (group I) with p less than 0.005.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic value of thallium-201 exercise scintigraphy in low-risk patients after Q-wave myocardial infarction: comparison with exercise testing and catheterization.

In a prospective study of 100 consecutive patients discharged after a Q-wave myocardial infarction, the value of reversible ischemia on thallium-201 scintigraphy to assess the risk of cardiac events (death or reinfarction) during 4 years was compared with variables from exercise testing and cardiac catheterization. Patients with markedly impaired left ventricular function [ejection fraction (EF) < or = 0.30] were excluded. During follow-up there were 20 cardiac events (10 cardiac deaths and 10 reinfarctions). Thallium-201 scintigraphy was significantly better than all exercise test variables and better than an EF < 0.40, with good sensitivity and specificity (75 and 51%, respectively). Exercise-induced reversible ischemia on scintigraphy yielded the same information as the presence of multivessel disease. Exercise test variables were of limited value to assess prognosis. Thus, thallium-201 scintigraphy can be used as the only tool to predict future cardiac events in low-risk patients after a Q-wave myocardial infarction.

Transesophageal color flow Doppler mapping in the assessment of native mitral valvular regurgitation: comparison with left ventricular angiography.

Transesophageal echocardiography (TEE) was performed within 24 hours after cardiac catheterization in 45 patients for assessment of native mitral valvular regurgitation. Color flow mapping was used in evaluating systolic regurgitant jet sizes. A jet demonstrated by TEE was 96% sensitive and 44% specific for angiographic mitral regurgitation. The presence of angiographic mitral regurgitation was best predicted by (single measurement) (1) a holosystolic jet, (2) a jet length greater than 2.5 cm, and (3) a jet area greater than 2 cm2. Severe angiographic mitral regurgitation (grades 3 and 4) was best predicted by (single measurement) (1) a jet area greater than 5 cm2, and (2) a jet length greater than 4 cm. It is concluded that the assessment of angiographic mitral regurgitation by TEE is improved by the measurement of these jet parameters, which have a high sensitivity and higher specificity than the presence of a jet alone. Furthermore, with TEE one is able to differentiate severe (grades 3 and 4) from absent or mild mitral regurgitation (grades 0, 1, and 2).

Independent prognostic value of supraventricular arrhythmias on 24-h ambulatory monitoring following myocardial infarction.

To determine the prognostic value of supraventricular arrhythmias, in addition to ventricular arrhythmias and clinical variables after myocardial infarction, 99 consecutive patients had 24-h ambulatory monitoring within 2 weeks of discharge. All patients completed at least 4-year follow-up (mean 56 +/- 6 months). During follow-up there were 29 cardiac events (13 cardiac deaths and 16 reinfarctions). The highest risk was associated with ventricular tachycardia (positive predictive accuracy 100%, negative predictive accuracy 75%, risk ratio 4.0) and supraventricular tachycardia i.e. paroxysmal tachycardia or AV nodal tachycardia (positive predictive accuracy 86%, negative predictive accuracy 80%, risk ratio 4.2). By multivariate analysis, supraventricular tachycardia proved to be an independent predictive variable, in addition to ventricular tachycardia, premature ventricular depolarisations greater than or equal to 10 h-1 and the presence of Killip class greater than or equal to II while in the coronary care unit for future cardiac events. These data suggest that supraventricular tachycardias detected on 24-h ambulatory monitoring shortly after discharge carry a poor prognosis and may indicate a different pathophysiology as compared to ventricular tachycardias.

Effects of nisoldipine on systolic and diastolic function in postinfarction patients with reduced left ventricular function: a randomized, double-blind, placebo controlled study.

The long-term effects of oral nisoldipine or placebo on clinical variables, exercise test results and echo Doppler-determined systolic and diastolic functions were studied in 30 consecutive patients with reduced left ventricular function (predischarge echocardiographic wall motion score greater than or equal to 8) following myocardial infarction. Groups were comparable in clinical variables, exercise results, echo Doppler measurements and coronary anatomy. During 6 months follow-up, death, reinfarction and bypass surgery or balloon angioplasty were equally distributed. A significant increase in exercise duration and time to onset of ST-depression was found in the nisoldipine treatment group, compared to the placebo group after 3 and 6 months. Time to onset of angina was not significantly different. Echocardiographic indices of left ventricular systolic function (ejection fraction and wall motion score) were unaltered; however, the time-velocity integral of the early diastolic filling phase and the early vs late diastolic flow velocity ratio were significantly increased while the atrial time-velocity integral vs total time-velocity integral was significantly decreased in the nisoldipine treatment group after 3 and 6 months of follow-up. In conclusion, nisoldipine reduced exercise-induced ischaemia, improved exercise capacity and diastolic left ventricular function in postinfarction patients with reduced left ventricular function.

Feasibility of emergency surgery for the treatment of an echocardiographically detected right atrial thrombus in a patient over 80 years of age presenting with shock.

We report the case of an 83-year old woman, presenting with progressive shock, in whom a right atrial thrombus was diagnosed by cross-sectional echocardiography. Doppler echocardiography demonstrated diastolic interruption of tricuspid inflow. Emergency thrombectomy was successful and without major complications despite the advanced age.

Analysis of time-activity curves related to myocardial metabolism. The case of 123I-heptadecanoic acid.

Time-activity curves are frequently used in the external assessment of the kinetics of radiolabelled non-esterified fatty acids. Analysis of time-activity curves is accomplished by fitting an analytical curve through the data points of the time-activity curve, resulting in two or more parameters of the curve fit. Before interpreting the results of curve fitting, the precision of each of the parameters has to be determined. In the present study the precision of the parameters of monoexponential plus constant curve fit of time-activity curves after administration of 123I-heptadecanoic acid was assessed for an acquisition time of 75 min. Two parameters were used, the T1/2 of the monoexponential and the ratio A/A+C, where A is the amplitude of the monoexponential and C the constant. A model study was used to assess the precision of the parameters of curve fitting. The precision of the parameters was calculated for wide ranges of the T1/2 (0-60 min), A/A+C (0-100%) and the noise content of the time-activity curve. The results are presented as the 10th and 90th percentiles.

An in vivo validation of quantitative blood flow imaging in arteries and veins using magnetic resonance phase-shift techniques.

Magnetic resonance (MR) techniques have recently been introduced, allowing quantitative measurement of blood flow with high spatial and temporal resolutions. These techniques are based on the phase of the MR signal rather than on the amplitude, and are referred to as MR phase or velocity mapping. Clinical validation is still lacking. We therefore performed an in vivo validation of such a technique in 17 healthy volunteers. Velocity maps were acquired at 50 ms intervals over the cardiac cycle in the aorta, superior and inferior vena cava. Plots were made of flow velocity and volume flow vs time and used for calculation of left ventricular stroke volume (SV), cardiac output (CO) and venous return. Comparison with Doppler ultrasound (x) yielded y = -7.5 + 1.1x (r = 0.76) for SV measurements (ml), and y = 0.3 + 0.9x (r = 0.86) for CO calculations (1 min-1). Comparison between MR SV (x) and MR determination of venous return (y), obtained by summation of the flow volumes per cardiac cycle in the superior and inferior vena cava, was close to identity, y = 1.3 + 1.0x (r = 0.91). Also, preliminary applications are presented in patients with aortic diseases. The findings of this study show that magnetic resonance velocity imaging can be accurately applied in vivo as a non-invasive means of measuring flow.

Effects of early intervention with low-dose aspirin (100 mg) on infarct size, reinfarction and mortality in anterior wall acute myocardial infarction.

Recently, it was shown that aspirin given early in acute myocardial infarction (AMI) improves hospital survival, but the mechanisms involved are unclear. In a prospective, randomized placebo-controlled trial, the influence of early intervention with low-dose aspirin (100 mg/day) on infarct size and clinical outcome was studied in 100 consecutive patients with first anterior wall AMI. Infarct size was calculated by cumulative lactate dehydrogenase release in the first 72 hours after admission and was found to be (mean +/- standard deviation) 1,431 +/- 782 U/liter in the aspirin group (n = 50) and 1,592 +/- 1,082 U/liter in the placebo group (n = 50, p = 0.35). The study medication was given for 3 months, during which mortality was 10 (20%) in the aspirin patients and 12 (24%) in the placebo patients (p = 0.65). However, reinfarction occurred in 2 patients (4%) in the aspirin group and in 9 (18%) in the placebo group (p less than 0.03). Early intervention with low-dose aspirin showed, in comparison to placebo, a 10% decrease of infarct size, but this difference was not statistically significant. However, early low-dose aspirin effectively decreased the risk of reinfarction. Therefore, the favor able results of early aspirin on mortality in acute myocardial infarction are probably due more to prevention of reinfarction than to decrease of infarct size.

Silent versus symptomatic myocardial ischemia during exercise testing: a comparison with coronary angiographic findings.

Two-hundred-and-eighty individuals with anginal complaints, without prior myocardial infarction and with a positive exercise stress test were divided into a group (n = 67) with exercise-induced silent myocardial ischemia and another group (n = 213) with exercise-induced angina pectoris. Both underwent coronary angiography and were compared with each other with respect to various exercise and angiographic parameters. Patients with exercise-induced silent ischemia attained a longer mean exercise duration (P less than 0.001), a higher peak exercise heart rate (P less than 0.0001) and a higher peak exercise rate pressure product (P less than 0.001) than patients with exercise-induced angina pectoris. In the latter group, more patients showed exercise-induced ST-segment depression greater than 2 mm (P less than 0.05). The group of patients with silent ischemia encompassed more individuals with normal coronary arteries (P less than 0.0001). More patients with exercise-induced angina pectoris had three-vessel disease (P less than 0.0001). The exclusion of patients with normal coronary arteries (23% in those with silent ischemia group and 6% in those with exercise-induced angina had no influence on the level of significance for peak heart rate, mean exercise duration and exercise duration greater than 10 min. Thus, in this population, exercise-induced silent myocardial ischemia is associated with better exercise performance and less extensive coronary arterial pathology than in exercise-induced angina pectoris.

Value of gadolinium-diethylene-triamine pentaacetic acid dynamics in magnetic resonance imaging of acute myocardial infarction with occluded and reperfused coronary arteries after thrombolysis.

The use of the paramagnetic contrast agent gadolinium-diethylene-triamine pentaacetic acid (DTPA) was evaluated in magnetic resonance imaging (MRI) of 18 patients with an acute myocardial infarction after thrombolysis. The patency of the infarct-related vessel was assessed by coronary angiography. At 58 +/- 9 hours after infarction MRI was performed before and after bolus injection of 0.1 mmol/kg gadolinium-DTPA. Myocardial signal intensities were measured using a circumferential profile. Normal and infarcted myocardium showed a maximum signal intensity enhancement of 35 and 66%, respectively. Signal intensity of infarcted relative to normal myocardium (I/N) increased from 1.06 +/- 0.16 before to a maximum of 1.39 +/- 0.13 after gadolinium-DTPA (p less than 0.001), whereas the contrast between normal myocardium and a pseudo-infarct region in 2 healthy volunteers did not change. Between patients with reperfused infarct-related vessels and occluded vessels without collaterals, maximum I/N did not differ. However, observing I/N as a function of time after injection of gadolinium-DTPA, the reperfusion group differed from the occlusion group on images acquired directly after injection (1.29 +/- 0.10 vs 1.14 +/- 0.05, p less than 0.02). Thus, gadolinium-DTPA enhanced the visualization of acute myocardial infarction on relatively longitudinal (T1)-weighted MR images and its dynamics seem of potential value for the noninvasive assessment of coronary artery reperfusion after thrombolysis.

Clinical value of studies with radioiodinated heptadecanoic acid in patients with coronary artery disease.

The results described in the literature of myocardial scintigraphy with radioiodinated heptadecanoic acid (IHDA) to detect coronary stenoses are contradictory. In the present study, IHDA scintigraphy was performed in nine control subjects and 67 patients with coronary artery disease. The acquisition time was 75 min and background correction was not applied. The time-activity curves of regions of interest were analyzed by curve fitting with a monoexponential plus constant. Two parameters were used: the halftime value of the monoexponential (T1/2 in min) and the ratio of the amplitude (A) of the monoexponential and the total activity at time t = 0 (amplitude + constant = A + C): A/A + C as a percentage. Based on the control group, a region of normal T1/2 values and A/A + C ratios was defined, for each calculated T1/2-A/A + C pair the probability of originating from a normal region was calculated. The value of the IHDA test, using the index of merit (sensitivity + specificity-100%), increased in the patient group without MI with the severity of the stenosis (21%, 24% and 47% for stenoses greater than or equal to 75%, greater than or equal to 90% and greater than or equal to 99%). In patients with MI, only small positive values in regions of non-infarct-related vessels were found (-1%-16%). It is concluded that the value of the IHDA test to detect stenoses of coronary arteries is too low to apply this test in clinical practice. However, a new type of analysis is offered, based on curve fitting of individual pixels.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of two-dimensional echocardiography for immediate detection of myocardial ischemia in the emergency room.

Inappropriate discharge from the emergency room of patients with acute chest pain may have serious consequences. Regional asynergy is one of the first signs of myocardial ischemia and can be detected with 2-dimensional echocardiography (2-DE). This study determines the value of 2-DE in the emergency room for immediate detection of myocardial ischemia causing acute chest pain at the time the electrocardiogram was nondiagnostic. Forty-three patients (32 men and 11 women) with a normal or nondiagnostic electrocardiogram during acute chest pain were studied with 2-DE. Only patients without a previous myocardial infarction and without known coronary artery disease (CAD) were studied. The entire left ventricular wall was examined for presence of regional asynergy. Coronary angiography was performed within 3 weeks. Cardiac enzyme levels were measured serially to establish or rule out an acute myocardial infarction. Sensitivity of 2-DE for detection of myocardial ischemia was 88% (22 of 25), specificity 78% (14 of 18), negative predictive accuracy 82% (14 of 17) and positive predictive accuracy 85% (22 of 26). Sensitivity of 2-DE for detection of acute myocardial infarction was 92% (12 of 13), specificity 53% (16 of 30) and negative predictive accuracy 94% (16 of 17). Thus, 2-DE during pain and a nondiagnostic electrocardiogram can readily identify patients with CAD in the emergency room, and it can accurately rule out an acute myocardial infarction.

The fate of 131I-17-iodoheptadecanoic acid during lactate loading: its oxidation is strongly inhibited in favor of its esterification. A radiochemical study in the canine heart.

The influence of lactate loading on fatty acid metabolism (pH = 7.4) by the normal canine heart was investigated radiochemically using the radioiodinated fatty acid 131I-17-iodoheptadecanoic acid (131I-17-HDA). Fatty acid metabolism was studied during control conditions (n = 8) and after lactate loading (n = 7). In the canine heart total myocardial 131I-17-HDA radioactivity (uptake) was not changed during the lactate intervention. The oxidation decreased fivefold (measured as free 131I-iodide ion) from 70% to 14% (p less than 0.0001, Student's t-test). Thin-layer chromatography of cardiac lipids demonstrated that the non-oxidized 131I-17-HDA was mainly stored in the triglycerides and phosphoglycerides. These results suggest that lactate inhibits cardiac 131I-HDA oxidation.

The influence of lactate and dipyridamole on myocardial fatty acid metabolism in man, traced with 123I-17-iodoheptadecanoic acid.

Changes in myocardial metabolism can be detected externally by registration of time-activity curves after administration of radioiodinated fatty acids. In this scintigraphic study the influence of lactate on fatty acid metabolism was investigated in the normal human myocardium, traced with 123I-17-iodoheptadecanoic acid (123I-17-HDA). In patients (paired, n = 7) lactate loading decreased the uptake of 123I-17-HDA significantly from 27 (control: 22-36) to 20 counts/min/pixel (16-31; p less than 0.05 Wilcoxon). The half-time value increased to more than 60 min (n = 5), oxidation decreased from 61 to 42%. Coronary vasodilatation, a well-known side effect of lactate loading, was studied separately in a dipyridamole study (paired, n = 6). Coronary vasodilatation did not influence the parameters of the time-activity curve. These results suggest that changes in plasma lactate level as occurring, among other effects, during exercise will influence the parameters of dynamic 123I-17-HDA scintigraphy of the heart.

Efficacy and safety of rate responsive pacing in patients with coronary artery disease and angina pectoris.

The present study included 17 patients with angina pectoris and coronary artery disease in whom a rate responsive ventricular pacemaker (Medtronic Activitrax) had been implanted. All patients had an exclusively paced rhythm. Single blinded, random, cross-over treadmill tests in the rate responsive pacing mode (VVIR) and in the fixed-rate demand mode (VVI) were performed, with an interval of 4-6 weeks. Mean exercise duration increased by 25% during VVIR pacing. Maximal heart rate increased significantly during VVIR compared to VVI pacing (VVI = 74 +/- 2 bpm, VVIR = 116 +/- 8 bpm, P less than 0.001) as did the rate-pressure product (VVI = 10.850 +/- 1,124, VVIR = 16.628 +/- 2,110, P less than 0.001). Despite improved performance, the number of anginal attacks per week and the nitroglycerin consumption did not show a significant difference between the two pacing modes. It is concluded that rate responsive pacing is beneficial and safe in patients with angina pectoris and coronary artery disease.

Short-term and long-term prognosis after myocardial infarction: prognostic value of coronary anatomy and left ventriculography.

To assess prospectively short-term (1 year) and long-term (4 years) prognostic variables from heart catheterization, 325 consecutive patients of 65 years or less who survived a myocardial infarction were studied. In all coronary angiography and left ventriculography was performed 4-6 weeks after infarction. First year mortality rate was significantly higher in patients with an ejection fraction less than 0.30 (20%) than in patients with an ejection fraction greater than or equal to 0.30 (2%, P less than 0.001). During 4-year follow-up cumulative mortality was 44% in patients with an ejection fraction less than 0.30 vs 11% in patients with an ejection fraction greater than or equal to 0.30 (P less than 0.001). In patients who survived the first year after infarction, however, a low ejection fraction less than 0.30 was not associated with higher mortality rate during the subsequent 3 years. Mortality in patients with one-, two- or three-vessel disease was equally distributed in the first year. After 4 years patients with three-vessel disease had a significant higher mortality (32%) than patients with two- or one-vessel disease (12 and 11%, respectively; P less than 0.05). Reinfarction rate was higher in patients with an ejection fraction less than 0.30 (14%) than in patients with an ejection fraction greater than or equal to 0.30 (3%, P less than 0.05) in the first year. During 4-year follow-up reinfarction rate was 38% in patients with an ejection fraction less than 0.30 vs. 13% in patients with an ejection fraction greater than or equal to 0.30 (P less than 0.05). Again, in patients who survived the first year without reinfarction, an ejection fraction less than 0.30 had no prognostic value for recurrent myocardial infarction during the subsequent three years. Three-vessel disease had no higher reinfarction rate in the first year of follow-up: during 4 years, patients with three-vessel disease had a reinfarction rate (32%) compared to patients with two- and one-vessel disease (14 and 11%, respectively; P less than 0.05). It is concluded that an ejection fraction less than 0.30 is a major risk factor for cardiac death and reinfarction only in the first year after myocardial infarction. Beyond the first year, a subgroup of patients with three-vessel disease is at risk for both cardiac death and reinfarction during the three subsequent years.