- Email: [email protected]
Safety of stress testing during the evolution of unstable angina pectoris or non–ST-elevation myocardial infarction
Safety of Stress Testing During the Evolution of Unstable Angina Pectoris or Non–ST-Elevation Myocardial Infarction Juhana Karha, MD, C. Michael Gibson, MS, MD, Sabina A. Murphy, MPH, Peter M. DiBattiste, MD, and Christopher P. Cannon, MD, for the TIMI Study Group Patients (n ⴝ 1,106) were chosen from the conservative arm of the Treat Angina with aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy—Thrombolysis In Myocardial Infarction (TACTICS-TIMI) 18 trial. Only 1 patient had a myocardial infarction and another died on the day of stress testing (mortality 0.12%). In patients with unstable angina pectoris or non–ST-elevation myocardial infarction treated with aspirin, heparin, and tirofiban, performance of an exercise or a pharmacologic stress test in selected patients within 48 to 72 hours after admission appears to be associated with a low risk of complications. 䊚2004 by Excerpta Medica Inc. (Am J Cardiol 2004;94:1537–1539)
tress testing is frequently performed to determine the presence and extent of myocardial ischemia after S unstable angina pectoris (UAP) or non–ST-elevation myocardial infarction (NSTEMI), and thereby guides the decision to perform coronary angiography. However, the safety of stress testing in the setting of UAP/NSTEMI has not been established in the modern era of aggressive medical therapy. The American College of Cardiology/ American Heart Association guidelines list NSTEMI within 3 days as a contraindication to stress testing.1 We hypothesized that performance of a stress test within 48 to 72 hours after UAP/NSTEMI, as carried out in the Treat Angina with aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy—Thrombolysis In Myocardial Infarction (TACTICS-TIMI) 18 trial, would be safe. •••
Patients (n ⫽ 1,106) were chosen from the conservative arm of the TACTICS-TIMI 18 trial. In the TACTICS-TIMI 18 trial, 2,220 patients with UAP/ NSTEMI were treated with aspirin, heparin, and tirofiban, and randomized to an early invasive strategy or to a conservative strategy in which cardiac catheterization was performed only if the patient had objective evidence of recurrent ischemia or an abnormal stress From the TIMI Study Group, the Department of Medicine, Brigham & Women’s Hospital, Boston, Massachusetts; Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio; and Merck & Co., Inc., West Point, Pennsylvania. This study (TIMI 18) was supported in part by a grant from Merck, Inc., Blue Bell, Pennsylvania. Dr. Karha’s address is: Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Desk F-15, 9500 Euclid Avenue, Cleveland, Ohio, 44195. E-mail: [email protected]. Manuscript received June 2, 2004; revised manuscript received and accepted August 2, 2004 ©2004 by Excerpta Medica Inc. All rights reserved. The American Journal of Cardiology Vol. 94 December 15, 2004
test performed within 48 to 72 hours.2 The protocol specified that patients who were able to exercise and had a normal baseline electrocardiogram undergo exercise stress testing according to the protocol of the institution. The protocol mandated that the stress test be limited to the completion of stage 2 of a standard Bruce protocol or an equivalent workload on another exercise protocol. The study protocol required that for patients with abnormal baseline electrocardiograms, either radionuclide imaging or echocardiography were included with the stress test. Additional nuclear perfusion imaging or echocardiography was used in 83% of the patients according to the protocol of the institution. Patients who were not candidates for exercise testing underwent a pharmacologic stress test using adenosine, persantine, or dobutamine. We assessed the safety of stress testing by determining the risk of death and myocardial infarction. Death and myocardial infarction were considered complications of the stress test if they occurred on the day of the stress test. Myocardial infarction was defined as previously described.3 In a separate analysis, patients (n ⫽ 633) were chosen from the conservative arm of the TIMI 3B trial.4 In the TIMI 3B trial, 1,473 patients with UAP/ NSTEMI treated with aspirin, heparin, and study drug (tissue plasminogen activator vs placebo) were randomized to either early invasive or conservative therapy. Patients in the conservative arm underwent stress testing 4 to 5 days after admission. Death and myocardial infarction were considered complications of the stress test if they occurred on the day of the stress test. All analyses were performed using Stata software, version 7.0 (Stata Corp LP, College Station, Texas). For each protocol, patients who developed spontaneous recurrent ischemia before stress testing underwent cardiac catheterization instead, and a total of 259 patients in the conservative arm did not undergo a stress test. In all, 847 patients underwent stress testing. Of these 847, 494 underwent an exercise treadmill test and 353 underwent a pharmacologic stress test with adenosine (n ⫽ 122), persantine (n ⫽ 152), or dobutamine (n ⫽ 79). Baseline characteristics and presenting features are listed in Table 1. The median interval between randomization and the stress test was 2 days, and 729 of the stress tests (86.1%) were performed within 3 days of randomization, as mandated by the protocol. In all, 314 patients underwent exercise stress testing using a standard Bruce protocol, and 114 underwent a modified Bruce protocol. Sixty-six patients had 0002-9149/04/$–see front matter doi:10.1016/j.amjcard.2004.08.033
1537
TABLE 1 Baseline Characteristics (n ⫽ 847) Variable Age (yrs) (mean ⫾ SD) Men White race Previous myocardial infarction Diabetes mellitus Previous aspirin therapy ST deviation ST-deviation or T-wave inversion Non–Q-wave myocardial infarction Troponin T ⬎0.01
61.2 ⫾ 12.0 67.5% 78.0% 38.7% 27.2% 65.9% 33.5% 56.6% 36.8% 49.8%
TABLE 2 Stress Test Results Variable Blood pressure response* Blunted Abnormal Heart rate response* Blunted Abnormal Angina during exercise test Angina during pharmacologic test ST deviation during exercise test ST deviation during pharmacologic test Nuclear imaging ischemia (exercise test)† Nuclear imaging ischemia (pharmacologic test)† Nuclear imaging fixed defect (exercise test)† Nuclear imaging fixed defect (pharmacologic test)† Echocardiographic new wall motion abnormality (exercise test) Echocardiographic new wall motion abnormality (pharmacologic test)
8.6% 7.8% 14.0% 2.5% 25.0% 25.9% 38.2% 18.0% 31.1% 24.4% 41.3% 45.6% 15.1% 20.4%
*Blood pressure and heart rate responses refer to exercise testing. † Nuclear imaging was performed using single-photon emission computed tomography.
a Cornell or other protocol used in the exercise stress testing. The mean ⫾ SD duration of testing among patients who underwent an exercise treadmill test using a standard Bruce protocol was 7.6 ⫾ 3.2 minutes. Of these patients, 56.4% reached stage ⱖ3, and 88.8% reached stage ⱖ2. Of the 114 patients who underwent a modified Bruce protocol, 69.3% reached stage ⱖ3, and 92.1% reached stage ⱖ2. Results of stress testing are listed in Table 2. Only 1 death occurred on the day of stress testing (mortality, 1 of 847 [0.12%]; 95% confidence interval [CI] 0% to 0.66%, n ⫽ 847). This death occurred 3 hours and 53 minutes after the start of an exercise stress test and was caused by ventricular tachycardia and/or ventricular fibrillation. The patient who died had elevated troponin on admission and transient STsegment elevation on the admission electrocardiogram. This patient exercised a total of 7 minutes according to standard Bruce protocol and had normal heart rate and blood pressure responses during testing. The patient developed chest discomfort during the test, but had no ischemic electrocardiographic changes. The mortality rate for patients with an elevated admission troponin was 0.29% (95% CI 0% to 1.6%, 1538 THE AMERICAN JOURNAL OF CARDIOLOGY姞
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n ⫽ 347). For patients with normal admission troponin, the mortality rate was 0% (95% CI 0% to 1.0%, n ⫽ 350). The mortality rate for patients with STsegment deviation on the admission electrocardiogram was 0.35% (95% CI 0% to 1.9%, n ⫽ 284). For patients with no ST-segment deviation on the admission electrocardiogram, the mortality rate was 0% (95% CI 0% to 0.65%, n ⫽ 563). Only 1 patient had a myocardial infarction on the day of stress testing (1 of 847 [0.12%]; 95% CI 0% to 0.66%, n ⫽ 847). Notably, this patient had evidence of ischemia on the stress test and proceeded to undergo percutaneous coronary intervention. Myocardial infarction occurred after percutaneous coronary intervention. Among patients in the conservative arm of the TIMI 3B trial, there were no deaths on the day of stress testing (1-sided 97.5% CI 0.6%, n ⫽ 633). Two patients (0.3%) had a myocardial infarction on the day of stress testing (95% CI 0% to 1.1%, n ⫽ 633). •••
In patients with UAP/NSTEMI treated with aspirin, heparin, and tirofiban, who are at moderate to high risk of recurrent cardiac events, performance of an exercise or a pharmacologic stress test within 48 to 72 hours after admission is associated with a low risk of complications of the test. This is the first study to demonstrate the safety of stress testing in this population of higher risk, unstable patients in the modern era of aggressive medical therapy. The mortality rate on the day of stress testing was 0.12%, and the rate of (recurrent) myocardial infarction was 0.12%. Myocardial infarction occurred after a percutaneous coronary intervention that was done after the stress test, and was likely related to the procedure. This complication rate was similar to what patients in the conservative arm of the TIMI 3B trial experienced. Patients in the TIMI 3B trial underwent stress testing later than in the TACTICS-TIMI 18 trial and did not receive a platelet glycoprotein IIb/IIIa inhibitor. Thus, in the setting of augmented antiplatelet therapy, earlier stress testing carried a similar risk of complications. This study has several limitations. First, this is a post hoc analysis and has all of the limitations associated with such a review. Second, the decision to proceed with exercise stress testing was made in a random fashion, and, as such, these results reflect the outcome in a select subpopulation from the conservatively managed arm of the TACTICS-TIMI 18 study. Finally, the sample size was relatively small, and the confidence intervals around the event rates are consequently wide. As such, these rates should be considered rough estimates. The real event rate in this group could be somewhat higher, as reflected by the upper bound of the confidence interval. Previous studies have noted that the incidence of death and myocardial infarction during stress testing of stable outpatients with known or suspected coronary artery disease is 1 in 2,500 tests.5 Among patients who have been stabilized for UAP, the incidence of death or myocardial infarction within 24 hours after stress testing generally performed 4 to 7 days after UAP has been estimated at 0.5%.6 –9 Furthermore, 1 DECEMBER 15, 2004
small study found that there were no deaths after a submaximal exercise treadmill protocol 3 days after ST elevation myocardial infarction (n ⫽ 126).10 Other previous observations include work by Senaratne et al,11 who showed that there were no cardiac arrests, deaths, or myocardial infarctions during stress testing performed within 72 hours after myocardial infarction in 216 patients. 1. Gibbons RJ, on behalf of the American College of Cardiology/American Heart
Association Task Force on Practice Guidelines. Committee to Update the 1997 Exercise Testing Guidelines. ACC/AHA 2002 Guideline Update for Exercise Testing: Summary Article. A Report of the ACC/AHA Task Force on Practice Guidelines (Committee to Update the 1997 Exercise Testing Guidelines). J Am Coll Cardiol 2002;40:1531–1540. 2. Cannon CP, Weintraub WS, Demopoulos LA, Vicari R, Frey MJ, Lakkis N, Neumann FJ, Robertson DH, DeLucca PT, DiBattiste PM, Gibson CM, Braunwald E. Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 2001;344:1879 –1887. 3. Cannon CP, McCabe CH, Wilcox RG, Langer A, Caspi A, Berink P, Lopez-Sendon J, Toman J, Charlesworth A, Anders RJ, Alexander JC, Skene A, Braunwald E. Oral glycoprotein IIb/IIIa inhibition with orbofiban in
patients with unstable coronary syndromes (OPUS-TIMI 16) trial. Circulation 2000;102:149 –156. 4. The TIMI IIIB Investigators. Effects of tissue plasminogen activator and a comparison of early invasive and conservative strategies on unstable angina and non-Q-wave myocardial infarction. Results of the TIMI IIIB Trial. Circulation 1994;89:1545–1556. 5. Stuart RJJ, Ellestad MH. National survey of exercise stress testing facilities. Chest 1980;77:94 –97. 6. Stein RA, Chaitman BR, Balady GJ, Fleg JL, Limacher MC, Pina IL, Williams MA, Bazzarre T. Safety and utility of exercise testing in emergency room chest pain centers: an advisory from the Committee on Exercise, Rehabilitation, and Prevention, Council on Clinical Cardiology, American Heart Association. Circulation 2000;102:1463–1467. 7. Butman SM, Olsen HG, Gardin JM, Piters KM, Hullett M, Butman LK. Submaximal exercise testing after stabilization of unstable angina pectoris. J Am Coll Cardiol 1984;4:667– 673. 8. Swahn E, Areshog M, Wallentin L. Early exercise testing after coronary care for suspected unstable coronary artery disease—safety and diagnostic value. Eur Heart J 1986;7:594 – 601. 9. Wilcox I, Freedman SB, Allman KC, Collins FL, Leitch JW, Kelly DT, Harris PJ. Prognostic significance of a predischarge exercise testing in risk stratification after unstable angina pectoris. J Am Coll Cardiol 1991;18:677– 683. 10. Topol EJ, Burek K, O’Neill WW, Kewman DG, Kender NH, Shea MJ, Schork MA, Kirscht J, Juni JE, Pitt B. A randomised controlled trial of hospital discharge three days after myocardial infarction in the era of reperfusion. N Engl J Med 1988;318:1083–1088. 11. Senaratne MP, Smith G, Gulamhusein SS. Feasibility and safety of early exercise testing using the Bruce protocol after acute myocardial infarction. J Am Coll Cardiol 2000;35:1212–1220.
Comparison of Eight- Versus 16-Slice MultidetectorRow Computed Tomography for Visibility and Image Quality of Coronary Segments Takao Maruyama, MD, Tohru Yoshizumi, RT, Ritsu Tamura, MD, Shigekazu Takashima, MD, Hiroyuki Toyoshima, MD, Ichiro Konishi, Shizuya Yamashita, MD, and Kouichi Yamasaki, MD Ten patients who underwent conventional coronary angiography (CA) were examined with both 8- and 16-slice multidetector-row computed tomography (MDCT) angiography within 6 months, and visibility and image quality of 16-slice MDCT-CA were compared with those of 8-slice MDCT-CA directly. In 136 segments determined by conventional CA, 101 (74.3%) and 126 (92.6%) segments were judged assessable by 8- and 16-slice MDCT-CA, respectively. Segment visibility in the right coronary and left circumflex arteries, as well as distal segments and small segments with diameters of <3.0 mm, was higher using 16-slice MDCT-CA than that of 8-slice MDCT-CA. As causes for invisibility in segments considered to be invisible, adjacent structures, as well as small diameters, were reduced by 16-slice MDCT-CA, suggesting that high spatial resolution contributes From the Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, Osaka; and the Departments of Radiology and Internal Medicine, Minoh City Hospital, Minoh, Japan. Dr. Maruyama’s address is: Department of Internal Medicine and Molecular Science, B5, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail: [email protected]. Manuscript received April 14, 2004; revised manuscript received and accepted August 10, 2004. ©2004 by Excerpta Medica Inc. All rights reserved. The American Journal of Cardiology Vol. 94 December 15, 2004
MD,
to higher visibility; however, nonassessable segments due to extensive calcium by 8-slice MDCT-CA were also judged nonassessable by 16-slice MDCT-CA. 䊚2004 by Excerpta Medica Inc. (Am J Cardiol 2004;94:1539 –1543)
n recent years, 4-slice multidetector-row computed tomography (MDCT), which acquires 4 sections Isimultaneously, has been introduced; some previous reports have also demonstrated the usefulness of MDCT-coronary angiography (CA).1–11 However, low visibility of coronary segments, especially in the right coronary and left circumflex arteries, as well as distal segments and branches, has been recognized as a limitation of 4-slice MDCT-CA. Eight-slice MDCT, which can acquire 8 slices simultaneously, has been introducted to the market. The entire heart can be scanned for approximately 20 seconds by 8-slice MDCT, but visibility of segments in the left circumflex artery and distal segments is still poor.12 Recently, the latest generation 16-slice MDCT has been developed, which acquires 16 slices simultaneously.13,14 For cardiac imaging, 16-slice MDCT is expected to have higher spatial resolution than that of 4- and 8-slice MDCT; however, little is known about the improvement in image quality of 16-slice MDCT-CA in direct comparison with the former version of 0002-9149/04/$–see front matter doi:10.1016/j.amjcard.2004.08.034
1539
tress testing is frequently performed to determine the presence and extent of myocardial ischemia after S unstable angina pectoris (UAP) or non–ST-elevation myocardial infarction (NSTEMI), and thereby guides the decision to perform coronary angiography. However, the safety of stress testing in the setting of UAP/NSTEMI has not been established in the modern era of aggressive medical therapy. The American College of Cardiology/ American Heart Association guidelines list NSTEMI within 3 days as a contraindication to stress testing.1 We hypothesized that performance of a stress test within 48 to 72 hours after UAP/NSTEMI, as carried out in the Treat Angina with aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy—Thrombolysis In Myocardial Infarction (TACTICS-TIMI) 18 trial, would be safe. •••
Patients (n ⫽ 1,106) were chosen from the conservative arm of the TACTICS-TIMI 18 trial. In the TACTICS-TIMI 18 trial, 2,220 patients with UAP/ NSTEMI were treated with aspirin, heparin, and tirofiban, and randomized to an early invasive strategy or to a conservative strategy in which cardiac catheterization was performed only if the patient had objective evidence of recurrent ischemia or an abnormal stress From the TIMI Study Group, the Department of Medicine, Brigham & Women’s Hospital, Boston, Massachusetts; Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio; and Merck & Co., Inc., West Point, Pennsylvania. This study (TIMI 18) was supported in part by a grant from Merck, Inc., Blue Bell, Pennsylvania. Dr. Karha’s address is: Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Desk F-15, 9500 Euclid Avenue, Cleveland, Ohio, 44195. E-mail: [email protected]. Manuscript received June 2, 2004; revised manuscript received and accepted August 2, 2004 ©2004 by Excerpta Medica Inc. All rights reserved. The American Journal of Cardiology Vol. 94 December 15, 2004
test performed within 48 to 72 hours.2 The protocol specified that patients who were able to exercise and had a normal baseline electrocardiogram undergo exercise stress testing according to the protocol of the institution. The protocol mandated that the stress test be limited to the completion of stage 2 of a standard Bruce protocol or an equivalent workload on another exercise protocol. The study protocol required that for patients with abnormal baseline electrocardiograms, either radionuclide imaging or echocardiography were included with the stress test. Additional nuclear perfusion imaging or echocardiography was used in 83% of the patients according to the protocol of the institution. Patients who were not candidates for exercise testing underwent a pharmacologic stress test using adenosine, persantine, or dobutamine. We assessed the safety of stress testing by determining the risk of death and myocardial infarction. Death and myocardial infarction were considered complications of the stress test if they occurred on the day of the stress test. Myocardial infarction was defined as previously described.3 In a separate analysis, patients (n ⫽ 633) were chosen from the conservative arm of the TIMI 3B trial.4 In the TIMI 3B trial, 1,473 patients with UAP/ NSTEMI treated with aspirin, heparin, and study drug (tissue plasminogen activator vs placebo) were randomized to either early invasive or conservative therapy. Patients in the conservative arm underwent stress testing 4 to 5 days after admission. Death and myocardial infarction were considered complications of the stress test if they occurred on the day of the stress test. All analyses were performed using Stata software, version 7.0 (Stata Corp LP, College Station, Texas). For each protocol, patients who developed spontaneous recurrent ischemia before stress testing underwent cardiac catheterization instead, and a total of 259 patients in the conservative arm did not undergo a stress test. In all, 847 patients underwent stress testing. Of these 847, 494 underwent an exercise treadmill test and 353 underwent a pharmacologic stress test with adenosine (n ⫽ 122), persantine (n ⫽ 152), or dobutamine (n ⫽ 79). Baseline characteristics and presenting features are listed in Table 1. The median interval between randomization and the stress test was 2 days, and 729 of the stress tests (86.1%) were performed within 3 days of randomization, as mandated by the protocol. In all, 314 patients underwent exercise stress testing using a standard Bruce protocol, and 114 underwent a modified Bruce protocol. Sixty-six patients had 0002-9149/04/$–see front matter doi:10.1016/j.amjcard.2004.08.033
1537
TABLE 1 Baseline Characteristics (n ⫽ 847) Variable Age (yrs) (mean ⫾ SD) Men White race Previous myocardial infarction Diabetes mellitus Previous aspirin therapy ST deviation ST-deviation or T-wave inversion Non–Q-wave myocardial infarction Troponin T ⬎0.01
61.2 ⫾ 12.0 67.5% 78.0% 38.7% 27.2% 65.9% 33.5% 56.6% 36.8% 49.8%
TABLE 2 Stress Test Results Variable Blood pressure response* Blunted Abnormal Heart rate response* Blunted Abnormal Angina during exercise test Angina during pharmacologic test ST deviation during exercise test ST deviation during pharmacologic test Nuclear imaging ischemia (exercise test)† Nuclear imaging ischemia (pharmacologic test)† Nuclear imaging fixed defect (exercise test)† Nuclear imaging fixed defect (pharmacologic test)† Echocardiographic new wall motion abnormality (exercise test) Echocardiographic new wall motion abnormality (pharmacologic test)
8.6% 7.8% 14.0% 2.5% 25.0% 25.9% 38.2% 18.0% 31.1% 24.4% 41.3% 45.6% 15.1% 20.4%
*Blood pressure and heart rate responses refer to exercise testing. † Nuclear imaging was performed using single-photon emission computed tomography.
a Cornell or other protocol used in the exercise stress testing. The mean ⫾ SD duration of testing among patients who underwent an exercise treadmill test using a standard Bruce protocol was 7.6 ⫾ 3.2 minutes. Of these patients, 56.4% reached stage ⱖ3, and 88.8% reached stage ⱖ2. Of the 114 patients who underwent a modified Bruce protocol, 69.3% reached stage ⱖ3, and 92.1% reached stage ⱖ2. Results of stress testing are listed in Table 2. Only 1 death occurred on the day of stress testing (mortality, 1 of 847 [0.12%]; 95% confidence interval [CI] 0% to 0.66%, n ⫽ 847). This death occurred 3 hours and 53 minutes after the start of an exercise stress test and was caused by ventricular tachycardia and/or ventricular fibrillation. The patient who died had elevated troponin on admission and transient STsegment elevation on the admission electrocardiogram. This patient exercised a total of 7 minutes according to standard Bruce protocol and had normal heart rate and blood pressure responses during testing. The patient developed chest discomfort during the test, but had no ischemic electrocardiographic changes. The mortality rate for patients with an elevated admission troponin was 0.29% (95% CI 0% to 1.6%, 1538 THE AMERICAN JOURNAL OF CARDIOLOGY姞
VOL. 94
n ⫽ 347). For patients with normal admission troponin, the mortality rate was 0% (95% CI 0% to 1.0%, n ⫽ 350). The mortality rate for patients with STsegment deviation on the admission electrocardiogram was 0.35% (95% CI 0% to 1.9%, n ⫽ 284). For patients with no ST-segment deviation on the admission electrocardiogram, the mortality rate was 0% (95% CI 0% to 0.65%, n ⫽ 563). Only 1 patient had a myocardial infarction on the day of stress testing (1 of 847 [0.12%]; 95% CI 0% to 0.66%, n ⫽ 847). Notably, this patient had evidence of ischemia on the stress test and proceeded to undergo percutaneous coronary intervention. Myocardial infarction occurred after percutaneous coronary intervention. Among patients in the conservative arm of the TIMI 3B trial, there were no deaths on the day of stress testing (1-sided 97.5% CI 0.6%, n ⫽ 633). Two patients (0.3%) had a myocardial infarction on the day of stress testing (95% CI 0% to 1.1%, n ⫽ 633). •••
In patients with UAP/NSTEMI treated with aspirin, heparin, and tirofiban, who are at moderate to high risk of recurrent cardiac events, performance of an exercise or a pharmacologic stress test within 48 to 72 hours after admission is associated with a low risk of complications of the test. This is the first study to demonstrate the safety of stress testing in this population of higher risk, unstable patients in the modern era of aggressive medical therapy. The mortality rate on the day of stress testing was 0.12%, and the rate of (recurrent) myocardial infarction was 0.12%. Myocardial infarction occurred after a percutaneous coronary intervention that was done after the stress test, and was likely related to the procedure. This complication rate was similar to what patients in the conservative arm of the TIMI 3B trial experienced. Patients in the TIMI 3B trial underwent stress testing later than in the TACTICS-TIMI 18 trial and did not receive a platelet glycoprotein IIb/IIIa inhibitor. Thus, in the setting of augmented antiplatelet therapy, earlier stress testing carried a similar risk of complications. This study has several limitations. First, this is a post hoc analysis and has all of the limitations associated with such a review. Second, the decision to proceed with exercise stress testing was made in a random fashion, and, as such, these results reflect the outcome in a select subpopulation from the conservatively managed arm of the TACTICS-TIMI 18 study. Finally, the sample size was relatively small, and the confidence intervals around the event rates are consequently wide. As such, these rates should be considered rough estimates. The real event rate in this group could be somewhat higher, as reflected by the upper bound of the confidence interval. Previous studies have noted that the incidence of death and myocardial infarction during stress testing of stable outpatients with known or suspected coronary artery disease is 1 in 2,500 tests.5 Among patients who have been stabilized for UAP, the incidence of death or myocardial infarction within 24 hours after stress testing generally performed 4 to 7 days after UAP has been estimated at 0.5%.6 –9 Furthermore, 1 DECEMBER 15, 2004
small study found that there were no deaths after a submaximal exercise treadmill protocol 3 days after ST elevation myocardial infarction (n ⫽ 126).10 Other previous observations include work by Senaratne et al,11 who showed that there were no cardiac arrests, deaths, or myocardial infarctions during stress testing performed within 72 hours after myocardial infarction in 216 patients. 1. Gibbons RJ, on behalf of the American College of Cardiology/American Heart
Association Task Force on Practice Guidelines. Committee to Update the 1997 Exercise Testing Guidelines. ACC/AHA 2002 Guideline Update for Exercise Testing: Summary Article. A Report of the ACC/AHA Task Force on Practice Guidelines (Committee to Update the 1997 Exercise Testing Guidelines). J Am Coll Cardiol 2002;40:1531–1540. 2. Cannon CP, Weintraub WS, Demopoulos LA, Vicari R, Frey MJ, Lakkis N, Neumann FJ, Robertson DH, DeLucca PT, DiBattiste PM, Gibson CM, Braunwald E. Comparison of early invasive and conservative strategies in patients with unstable coronary syndromes treated with the glycoprotein IIb/IIIa inhibitor tirofiban. N Engl J Med 2001;344:1879 –1887. 3. Cannon CP, McCabe CH, Wilcox RG, Langer A, Caspi A, Berink P, Lopez-Sendon J, Toman J, Charlesworth A, Anders RJ, Alexander JC, Skene A, Braunwald E. Oral glycoprotein IIb/IIIa inhibition with orbofiban in
patients with unstable coronary syndromes (OPUS-TIMI 16) trial. Circulation 2000;102:149 –156. 4. The TIMI IIIB Investigators. Effects of tissue plasminogen activator and a comparison of early invasive and conservative strategies on unstable angina and non-Q-wave myocardial infarction. Results of the TIMI IIIB Trial. Circulation 1994;89:1545–1556. 5. Stuart RJJ, Ellestad MH. National survey of exercise stress testing facilities. Chest 1980;77:94 –97. 6. Stein RA, Chaitman BR, Balady GJ, Fleg JL, Limacher MC, Pina IL, Williams MA, Bazzarre T. Safety and utility of exercise testing in emergency room chest pain centers: an advisory from the Committee on Exercise, Rehabilitation, and Prevention, Council on Clinical Cardiology, American Heart Association. Circulation 2000;102:1463–1467. 7. Butman SM, Olsen HG, Gardin JM, Piters KM, Hullett M, Butman LK. Submaximal exercise testing after stabilization of unstable angina pectoris. J Am Coll Cardiol 1984;4:667– 673. 8. Swahn E, Areshog M, Wallentin L. Early exercise testing after coronary care for suspected unstable coronary artery disease—safety and diagnostic value. Eur Heart J 1986;7:594 – 601. 9. Wilcox I, Freedman SB, Allman KC, Collins FL, Leitch JW, Kelly DT, Harris PJ. Prognostic significance of a predischarge exercise testing in risk stratification after unstable angina pectoris. J Am Coll Cardiol 1991;18:677– 683. 10. Topol EJ, Burek K, O’Neill WW, Kewman DG, Kender NH, Shea MJ, Schork MA, Kirscht J, Juni JE, Pitt B. A randomised controlled trial of hospital discharge three days after myocardial infarction in the era of reperfusion. N Engl J Med 1988;318:1083–1088. 11. Senaratne MP, Smith G, Gulamhusein SS. Feasibility and safety of early exercise testing using the Bruce protocol after acute myocardial infarction. J Am Coll Cardiol 2000;35:1212–1220.
Comparison of Eight- Versus 16-Slice MultidetectorRow Computed Tomography for Visibility and Image Quality of Coronary Segments Takao Maruyama, MD, Tohru Yoshizumi, RT, Ritsu Tamura, MD, Shigekazu Takashima, MD, Hiroyuki Toyoshima, MD, Ichiro Konishi, Shizuya Yamashita, MD, and Kouichi Yamasaki, MD Ten patients who underwent conventional coronary angiography (CA) were examined with both 8- and 16-slice multidetector-row computed tomography (MDCT) angiography within 6 months, and visibility and image quality of 16-slice MDCT-CA were compared with those of 8-slice MDCT-CA directly. In 136 segments determined by conventional CA, 101 (74.3%) and 126 (92.6%) segments were judged assessable by 8- and 16-slice MDCT-CA, respectively. Segment visibility in the right coronary and left circumflex arteries, as well as distal segments and small segments with diameters of <3.0 mm, was higher using 16-slice MDCT-CA than that of 8-slice MDCT-CA. As causes for invisibility in segments considered to be invisible, adjacent structures, as well as small diameters, were reduced by 16-slice MDCT-CA, suggesting that high spatial resolution contributes From the Department of Internal Medicine and Molecular Science, Graduate School of Medicine, Osaka University, Osaka; and the Departments of Radiology and Internal Medicine, Minoh City Hospital, Minoh, Japan. Dr. Maruyama’s address is: Department of Internal Medicine and Molecular Science, B5, Graduate School of Medicine, Osaka University, 2-2, Yamadaoka, Suita, Osaka 565-0871, Japan. E-mail: [email protected]. Manuscript received April 14, 2004; revised manuscript received and accepted August 10, 2004. ©2004 by Excerpta Medica Inc. All rights reserved. The American Journal of Cardiology Vol. 94 December 15, 2004
MD,
to higher visibility; however, nonassessable segments due to extensive calcium by 8-slice MDCT-CA were also judged nonassessable by 16-slice MDCT-CA. 䊚2004 by Excerpta Medica Inc. (Am J Cardiol 2004;94:1539 –1543)
n recent years, 4-slice multidetector-row computed tomography (MDCT), which acquires 4 sections Isimultaneously, has been introduced; some previous reports have also demonstrated the usefulness of MDCT-coronary angiography (CA).1–11 However, low visibility of coronary segments, especially in the right coronary and left circumflex arteries, as well as distal segments and branches, has been recognized as a limitation of 4-slice MDCT-CA. Eight-slice MDCT, which can acquire 8 slices simultaneously, has been introducted to the market. The entire heart can be scanned for approximately 20 seconds by 8-slice MDCT, but visibility of segments in the left circumflex artery and distal segments is still poor.12 Recently, the latest generation 16-slice MDCT has been developed, which acquires 16 slices simultaneously.13,14 For cardiac imaging, 16-slice MDCT is expected to have higher spatial resolution than that of 4- and 8-slice MDCT; however, little is known about the improvement in image quality of 16-slice MDCT-CA in direct comparison with the former version of 0002-9149/04/$–see front matter doi:10.1016/j.amjcard.2004.08.034
1539