Simon H. Braat

Value of electrocardiogram in diagnosing right ventricular involvement in patients with an acute inferior wall myocardial infarction.

To study the value of the electrocardiogram in diagnosing right ventricular involvement in acute inferior wall myocardial infarction, the electrocardiographic findings were analysed in 67 patients who had had scintigraphy to pin-point the infarct. All 67 patients were consecutively admitted because of an acute inferior wall infarction. A 12 lead electrocardiogram with four additional right precordial leads (V3R, V4R, V5R, and V6R) was routinely recorded on admission and every eight hours thereafter for three consecutive days. Thirty-six to 72 hours after the onset of chest pain a 99mtechnetium pyrophosphate scintigraphy and a dynamic flow study were performed to detect right ventricular involvement, which was found in 29 of the 67 patients (43%). ST segment elevation greater than or equal to 1 mm in leads V3R, V4R, V5R, and V6R is a reliable sign of right ventricular involvement. ST segment elevation greater than or equal to 1 mm in lead V4R was found to have the greatest sensitivity (93%) and predictive accuracy (93%). The diagnostic value of a QS pattern in lead V3R and V4R or ST elevation greater than or equal to 1 mm in lead V1 was much lower. ST segment elevation in the right precordial leads was short lived, having disappeared within 10 hours after the onset of chest pain in half of our patients with right ventricular involvement. When electrocardiograms are recorded in patients with an acute inferior wall infarction within 10 hours after the onset of chest pain, additional right ventricular infarction can easily be diagnosed by recording lead V4R.

Myocardial Perfusion Imaging With 99mTc Tetrofosmin Comparison to 201Tl Imaging and Coronary Angiography in a Phase III Multicenter Trial

Background Our objective was to compare the sensitivity and specificity of tetrofosmin, a new 99m Tc-labeled myocardial perfusion imaging agent for the detection of myocardial perfusion abnormalities, with those of 201 Tl and coronary angiography. Our hypothesis was that same-day stress/rest tetrofosmin imaging could provide data comparable to those of 201 Tl imaging. Myocardial perfusion imaging plays an important role for the evaluation of coronary artery disease. Newer 99m Tc-labeled agents offer several advantages over 201 Tl, the conventional myocardial perfusion imaging agent. Tetrofosmin is a new 99m Tc-labeled agent with promising results in preliminary studies. Methods and Results Two hundred fifty-two patients with suspected coronary artery disease were enrolled in 10 centers in the United States and Europe. All patients underwent exercise and rest myocardial perfusion imaging with 99m Tc-tetrofosmin using two separate injections of the radiotracer 4 hours apart on the same day. Planar images were obtained in three standard views 15 to 60 minutes after radiotracer injection. Patients also underwent standard exercise and redistribution planar 201 Tl imaging within 2 weeks of tetrofosmin imaging. In addition, 58 healthy subjects with low likelihood of coronary artery disease underwent exercise and rest tetrofosmin imaging. Coronary angiograms were available in 181 patients with suspected coronary artery disease. All radionuclide images were processed in the central core laboratory and interpreted blindly by a panel of four experienced readers. 201 Tl images and tetrofosmin images were read separately. Discrepancies were resolved by consensus. The workload, peak heart rate, and double products were comparable during exercise for both imaging agents. Technically acceptable paired 201 Tl and tetrofosmin images were available in 224 of 252 patients. Tetrofosmin images were generally of good quality, with low extracardiac activity, and easy to interpret. Patients were categorized as showing normal, ischemia, infarction, or mixture with each imaging modality. Precise concordance for each of these categories was 59.4% (κ=0.44; 95% CI, 0.35 to 0.53). When patients were categorized as normal or abnormal, the concordance was 80.4% (κ=0.55; 95% CI, 0.43 to 0.67). When each of five anatomic territories (septal, anterior, inferior, lateral, and apical) was categorized as normal versus abnormal, the concordance varied from 81% to 90%. When similar comparison was made for the specific category of abnormality, the concordance was 64% to 84%. When coronary angiography was used as the criterion, the sensitivity and positive and negative predictive accuracy of tetrofosmin and 201 Tl were comparable. The normalcy rate of tetrofosmin images in the healthy subjects with low likelihood of coronary artery disease was 97%. Conclusions 99m Tc tetrofosmin is a new myocardial imaging agent with favorable imaging characteristics with results comparable to those of 201 Tl.Background Our objective was to compare the sensitivity and specificity of tetrofosmin, a new 99m Tc-labeled myocardial perfusion imaging agent for the detection of myocardial perfusion abnormalities, with those of 201 Tl and coronary angiography. Our hypothesis was that same-day stress/rest tetrofosmin imaging could provide data comparable to those of 201 Tl imaging. Myocardial perfusion imaging plays an important role for the evaluation of coronary artery disease. Newer 99m Tc-labeled agents offer several advantages over 201 Tl, the conventional myocardial perfusion imaging agent. Tetrofosmin is a new 99m Tc-labeled agent with promising results in preliminary studies. Methods and Results Two hundred fifty-two patients with suspected coronary artery disease were enrolled in 10 centers in the United States and Europe. All patients underwent exercise and rest myocardial perfusion imaging with 99m Tc-tetrofosmin using two separate injections of the radiotracer 4 hours apart on the same day. Planar images were obtained in three standard views 15 to 60 minutes after radiotracer injection. Patients also underwent standard exercise and redistribution planar 201 Tl imaging within 2 weeks of tetrofosmin imaging. In addition, 58 healthy subjects with low likelihood of coronary artery disease underwent exercise and rest tetrofosmin imaging. Coronary angiograms were available in 181 patients with suspected coronary artery disease. All radionuclide images were processed in the central core laboratory and interpreted blindly by a panel of four experienced readers. 201 Tl images and tetrofosmin images were read separately. Discrepancies were resolved by consensus. The workload, peak heart rate, and double products were comparable during exercise for both imaging agents. Technically acceptable paired 201 Tl and tetrofosmin images were available in 224 of 252 patients. Tetrofosmin images were generally of good quality, with low extracardiac activity, and easy to interpret. Patients were categorized as showing normal, ischemia, infarction, or mixture with each imaging modality. Precise concordance for each of these categories was 59.4% (κ=0.44; 95% CI, 0.35 to 0.53). When patients were categorized as normal or abnormal, the concordance was 80.4% (κ=0.55; 95% CI, 0.43 to 0.67). When each of five anatomic territories (septal, anterior, inferior, lateral, and apical) was categorized as normal versus abnormal, the concordance varied from 81% to 90%. When similar comparison was made for the specific category of abnormality, the concordance was 64% to 84%. When coronary angiography was used as the criterion, the sensitivity and positive and negative predictive accuracy of tetrofosmin and 201 Tl were comparable. The normalcy rate of tetrofosmin images in the healthy subjects with low likelihood of coronary artery disease was 97%. Conclusions 99m Tc tetrofosmin is a new myocardial imaging agent with favorable imaging characteristics with results comparable to those of 201 Tl.

Right ventricular involvement with acute inferior wall myocardial infarction identifies high risk of developing atrioventricular nodal conduction disturbances

In 67 consecutive patients with inferior wall acute myocardial infarction (AMI), 99m-technetium pyrophosphate scintigraphy was performed 36 to 72 hours after the onset of chest pain to detect right ventricular (RV) involvement. All patients were continuously monitored during at least 3 days to detect rhythm and conduction disturbances. In 29 patients RV involvement was diagnosed by scintigraphy. None of these 29 patients showed clinical signs of right-sided heart failure. Fourteen of the 19 patients showing atrioventricular (AV) nodal condution disturbances in the setting of inferior AMI also had RV involvement. Therefore, the incidence of high-degree AV nodal block in patients with RV involvement (14 of 29 patients) was 48% compared to only 13% (5 of 38) in patients with inferior AMI without RV involvement.

Value of lead V4R for recognition of the infarct coronary artery in acute inferior myocardial infarction.

In 84 patients with an acute inferior wall myocardial infarction (MI) admitted within 10 hours after the onset of chest pain, a right precordial lead V4R electrocardiogram was recorded in addition to the standard 12-lead electrocardiogram. The presence or absence of ST-segment elevation in lead V4R was correlated with results of coronary angiography performed 2 to 26 weeks (mean 10) after MI. Patients were classified into 3 groups: (1) those with a critical stenosis or occlusion proximal to the first right ventricular (RV) branch (27 patients); (2) those with stenosis distal to the right ventricular branch of the right coronary artery (36 patients); and (3) those with stenosis in the left circumflex coronary artery (21 patients). The presence of ST-segment elevation greater than or equal to 1 mm in lead V4R has a sensitivity of 100% and a specificity of 87% for occlusion of the right coronary artery above the first RV branch; the predictive accuracy is 92%. Seven of 36 patients with a distal occlusion of the right coronary artery showed ST-segment elevation of 1 mm or more in lead V4R . The absence of ST-segment elevation greater than or equal to 1 mm in lead V4R excluded proximal occlusion of the right coronary artery. ST-segment elevation in lead V4R was not seen either in 29 of 36 patients with a distal occlusion of the right coronary artery or in all patients with an occlusion of the left circumflex artery. Recording of lead V4R within 10 hours after onset of acute inferior wall MI can give information rapidly about the vessel responsible for MI.(ABSTRACT TRUNCATED AT 250 WORDS)

LACK OF NEGATIVE INOTROPIC EFFECTS OF THE NEW CALCIUM-ANTAGONIST RO-40-5967 IN PATIENTS WITH STABLE ANGINA-PECTORIS

We screened the antiischemic, hemodynamic, and inotropic effects of different dosages of the new calcium channel blocker Ro 40–5967 in 65 patients with stable effort-induced angina pectoris. In a double-blind way, patients were randomized to receive a single oral dose of 50, 100, or 200 mg Ro 40–5967 or placebo, given as a drinking solution. Left ventricular ejection fraction (LVEF), blood pressure (BP), and heart rate (HR) were measured at rest and during a supine bicycle exercise test on day 0 (baseline) and 2 h after drug intake on day 1. Twenty-four hours later, the bicycle exercise test was repeated. Ro 40–5967 improved exercise duration and resting LVEF. After 200 mg, exercise time increased significantly from 8.4 ± 0.8 min (mean ± SEM) to 9.6 ± 0.7 min (p = 0.018), and LVEF at rest increased from 54.5 ± 2.2 to 58.1 ± 2.6% (p = 0.045). Time to 0.1 mV ST-segment depression increased significantly from 4.3 ± 0.8 to 5.5 ± 0.9 min in the 100-mg group (p = 0.013) and from 4.3 ± 1.3 to 5.4 ± 1.5 min in the 200-mg group (p = 0.027). Maximum ST-segment depression decreased significantly at all dose levels (p = 0.01), with the maximum decrease noted in the 200-mg group (from 0.21 ± 0.03 to 0.15 ± 0.02 mV, p = 0.004). BP, HR, and rate-pressure product did not change significantly at rest or at maximum exercise. A single dose of Ro 40–5967 has antiischemic properties in patients with stable angina pectoris, with maximum effects obtained after 200 mg. No signs of negative inotropy were noted, and the drug was well tolerated.

Thallium-201 exercise scintigraphy and left bundle branch block

Abstract Results from several centers have shown that the sensitivity and specificity of exercise thallium-201 (Tl-201) myocardial imaging for detecting myocardial ischemia are superior to those of conventional exercise electrocardiography. 1–6 However, the value of Tl-201 myocardial imaging depends on patient selection, acquisition technique and mode (quantitative interpretation) of images. In patients with normal intraventricular conduction, sensitivity and specificity of Tl-201 exercise myocardial imaging has been reported as 85 to 90%, compared with 65 to 70% for exercise electrocardiography alone. 7 Limited information is available about the value of Tl-201 myocardial imaging in patients with left bundle branch block (LBBB). McGowan et al 8 examined 27 patients with LBBB using potassium-43 or rubidium-81 to exclude coronary artery disease (CAD). Hirzel et al 9 examined 19 patients by Tl-201 scintigraphy and coronary angiography for the same purpose. Both studies found a decreased septal uptake of the radionuclide, suggesting a narrowed left anterior descending coronary artery. However, most patients who had a septal defect had a normal left anterior descending coronary artery by coronary angiography. To further assess the value of Tl-201 myocardial imaging in patients with LBBB and chest pain and to study its relation to CAD, the present study was undertaken in 24 patients with LBBB admitted to the hospital because of chest pain.

Value of the ST-T segment in lead V4R in inferior wall acute myocardial infarction to predict the site of coronary arterial occlusion.

The treatment of acute myocardial infarction (AMI) has changed dramatically with the introduction of thrombolytic therapy, immediate angioplasty and emergency coronary artery bypass surgery. Several studies1e3 have shown that the success rate of these procedures depends on the time interval between the onset of complaints and the achievement of reperfusion. In patients admitted with an inferior wall AMI, the coronary artery causing the AM1 can be the right or the left circumflex artery. Our previous investigations, as well as those of others,4-6 have shown that the recording of lead V4R in the acute phase of an inferior wall AM1 can distinguish those patients with a proximal occlusion of the right coronary artery from those with an occlusion of the distal right or left circumflex artery, the first group of patients showing ST-T-segment elevation I1 mm in lead V4R. However, it is not possible to differentiate between occlusion of a distal right coronary artery and a circumflex artery using this criterion. In these patients (possible candidates for intracoronary thrombolytic therapy), coronary arteriography might start with the “wrong” coronary artery leading to a delay in reperfusion. Retrospectively, we have analyzed the configuration of the ST-T segment in lead V4R to determine if changes in the ST-T segment can help predict the site of coronary occlusion in inferior wall AMI.

Value of lead V4R in exercise testing to predict proximal stenosis of the right coronary artery

To assess the value of lead V4R during exercise testing for predicting proximal stenosis of the right coronary artery, 107 patients were studied. In all patients, a Bruce exercise test with the simultaneous recording of leads I, II, V4R, V1, V4 and V6 was followed by coronary angiography. Apart from registering ST segment changes in the conventional leads, all patients were classified according to absence or presence of an ST segment deviation of 1 mm or greater in lead V4R. Seventy-nine of the 107 patients were studied because of inadequate control of angina pectoris. Seven patients had had myocardial infarction before 40 years of age. Twenty-one patients were analyzed because of severe cardiac arrhythmias. In the 46 patients who had a previous myocardial infarction, the infarct location was inferior in 28 and anterior in 18. Seven of the 14 patients without myocardial infarction and significant proximal stenosis in the right coronary artery showed an ST segment deviation of 1 mm or greater in lead V4R during exercise. This was also observed in 11 of 18 patients with an old inferior wall infarction and proximal occlusion of the right coronary artery. None of the 53 patients without significant proximal stenosis in the right coronary artery showed exercise-related ST segment changes in lead V4R. Exercise-related ST segment deviation in lead V4R had a sensitivity of 56%, a specificity of 96% and a predictive accuracy of 84% in recognizing proximal stenosis in the right coronary artery. These observations indicate that the recording of lead V4R is of value for predicting or excluding proximal stenosis in the right coronary artery.

Right and left ventricular ejection fraction in acute inferior wall infarction with or without ST segment elevation in lead V4R.

To detect right ventricular involvement, lead V4R was recorded within 10 hours of the onset of chest pain in 42 consecutive patients admitted with acute inferior wall myocardial infarction. One week after the acute infarction, multigated equilibrium radionuclide ventriculography was performed to assess right and left ventricular ejection fraction. Two weeks after the acute infarction, coronary angiography was performed to determine the site and location of the obstruction leading to the infarction. Seventeen patients had an obstruction in the right coronary artery proximal to the first branch to the right ventricular free wall (group 1); all of these had ST segment elevation in lead V4R. Fourteen patients had an obstruction in the right coronary artery distal to the first branch to the right ventricular free wall (group 2); only two of these patients had ST segment elevation in lead V4R. In 11 patients, the obstruction was located in the circumflex coronary artery (group 3); none of these had ST segment elevation in lead V4R. Nineteen patients had ST segment elevation of 1 mm or greater in lead V4R (group 4). Left ventricular ejection fraction was not different among the four groups of patients, although the right ventricular ejection fraction was significantly lower in group 1 and group 4 patients. It is concluded that ST segment elevation in lead V4R reliably identifies the group of patients with inferior wall myocardial infarction with depressed right ventricular function. This phenomenon persists for at least 1 week after infarction.

Reperfusion with streptokinase of an occluded right coronary artery: Effects on early and late right and left ventricular ejection fraction

The effect of coronary artery recanalization on early and late right and left ventricular function was studied in patients with an acute inferior wall myocardial infarction caused by an occlusion of the right coronary artery. Fifty-four out of 138 patients, with chest pain lasting less than 4 hours, with ST elevations diagnostic for acute myocardial infarction not responding to medical treatment, and without contraindication for thrombolytic therapy, had an occluded right coronary artery. In 26 of these 54 patients, the occlusion was located proximal to the first right ventricular branch. Fourteen of them were treated conventionally (group A) and 12 with intracoronary streptokinase (group B). In 28 patients, the occlusion was distal to the first right ventricular branch. Fifteen were treated conventionally (group C) and 13 with intracoronary streptokinase (group D). In all patients, coronary angiograms were made 2 to 3 weeks after acute myocardial infarction. A nuclear angiogram was made the second day after admission and 3 months later to determine right and left ventricular ejection fraction. Values of radionuclide left and right ventricular ejection fraction (RVEF) between acute study (less than 48 hours after acute myocardial infarction [AMI]) and late study (3 months after AMI) showed no significant improvement in the four groups of patients studied. Group A patients (patients with total occlusion of the right coronary artery treated conventionally) had a significantly lower RVEF acutely and at late study as compared to the other three groups.(ABSTRACT TRUNCATED AT 250 WORDS)