Efficacy of Ultrasound-assisted Stress Testing Using a Hand-carried Ultrasound Device for Diagnosis of Coronary Artery Disease page 1
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Efficacy of Ultrasound-assisted Stress Testing Using a Hand-carried Ultrasound Device for Diagnosis of Coronary Artery Disease

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  • Efficacy of Ultrasound-assisted Stress TestingUsing a Hand-carried Ultrasound Device for

    Diagnosis of Coronary Artery DiseaseYutaka Hirano, MD, Hisakazu Uehara, MD, Hajime Nakamura, MD,Shin-ichirou Ikuta, MD, Manabu Nakano, MD, Seita Akiyama, MD,

    and Kinji Ishikawa, MD, Osaka, Japan

    Background: Exercise echocardiography is an effectivemeans of noninvasively detecting coronary artery dis-ease (CAD), and hand-carried cardiac ultrasound (HCU)devices are now being used to diagnose CAD in emer-gency rooms and at bedsides.Objective: To compare the efficacies of exercise echo-cardiography with an HCU device (EchoCG-HCU) andexercise electrocardiography (ECG) in the diagnosis ofCAD.Methods: Fifty-eight patients underwent symptom-lim-ited treadmill exercise testing. Two-dimensional echo-cardiographic images were obtained from standardparasternal and apical windows at rest and immediately

    after exercise using an HCU device (180 PLUS SonoSite

    doi:10.1016/j.echo.2006.01.006

    536

    Inc, Bothell, Wash). Wall motion was scored for each of16 left ventricular segments using a 5-point gradingsystem. The development of new or worsening wallmotion was considered to be indicative of ischemia.Results: When identifying CAD using exercise ECG, thesensitivity ws 63%, the specificity was 72%, and thediagnostic accuracy was 69%. By comparison, with exer-cise EchoCG-HCU the sensitivity was 68%, the specificitywas 90%, and the diagnostic accuracy was 83%. More-over, the specificity of exercise EchoCG-HCU was signif-icantly higher than that of exercise ECG (p < .05).Conclusion: Exercise EchoCG-HCU is at least as use-ful as exercise ECG for diagnosing CAD. (J Am Soc

    Echocardiogr 2006;19:536-539.)

    Although exercise echocardiography (EchoCG) isreportedly useful for diagnosing coronary artery dis-ease (CAD),1-4 in Japan there are few hospitals inwhich exercise EchoCG is performed, often becausethere is not enough space in the exercise room for astandard EchoCG machine. Recently, however, hand-carried ultrasound (HCU) devices have been appliedfor the diagnosis of CAD, and a number of studies haveconfirmed its usefulness as a screening device.5-11 Inthis study, we compared the diagnostic efficacy ofexercise electrocardiography (ECG) with that of exer-cise EchoCG using an HCU device (EchoCG-HCU).

    METHODS

    In all, 97 consecutive patients with chest pain who under-went treadmill exercise ECG in our hospital between August2003 and January 2004 were enrolled for this study. Ex-cluded were patients with valvular heart disease, cardiomy-

    From the Department of Cardiology, Kinki University School ofMedicine.Reprint requests: Yutaka Hirano, MD, Department of Cardiology,Kinki University School of Medicine, 377-2 Ohnohigashi, Osaka-sayama, Osaka 589-8511 Japan (E-mail: yuhirano-circ@umin.ac.jp).0894-7317/$32.00Copyright 2006 by the American Society of Echocardiography.

    opathy, unstable angina pectoris, or myocardial infarction.Patients underwent symptom-limited treadmill exercisetesting using a modified Ellestad or modified Naughtonprotocol. All examinations were initiated at 1 PM withoutchanging the patients medications. Before exercise, 2-di-mensional (2D) EchoCG images obtained from theparasternal long- and short-axis views and the apical 4- and2-chamber views were recorded using a HCU device (180Plus, SonoSite Inc, Bothell, Wash) (width 19 diameter6.3 height 34 cm; 2.6 kg) coupled to a digital video-camera (DCR-TRV18, SONY Co Ltd, Tokyo, Japan) andstored on digital videotape. During the treadmill exercise,blood pressure and 12-channel ECGs were recorded everyminute. The criterion for CAD was S-T segment depressionof more than 0.1 mV at 80 milliseconds after the J-point.Exercise was discontinued if the patient had chest pain orleg fatigue, if the heart rate reached the target heart rate,or if the ECG showed S-T segment depression of morethan 0.2 mV at 80 milliseconds after the J-point. Immedi-ately after exercise, the patients were placed in the leftdecubitus position and ECGs and EchoCG-HCUs wererecorded. Left ventricular regional wall motion was sub-sequently analyzed using the 16-segment model12 of theAmerican Society of Echocardiography with 5 gradesranging from normokinesis to dyskinesis. The criterion forCAD was the onset of new wall-motion abnormalities.Segments were assigned to the territories of 3 coronaryarteries (left anterior descending, left circumflex, and

    right) according to the vascular distribution of the seg-

  • Journal of the American Society of EchocardiographyVolume 19 Number 5 Hirano et al 537

    ments.13 In addition, within 2 weeks after exercise,coronary angiography was performed using Judkins tech-nique. Significant coronary stenosis was defined as greaterthan 75% lumenal diameter stenosis of a coronary artery.

    Wall motion was evaluated by two independent, experi-enced echocardiographers (physicians) who were not in-formed of the results of treadmill ECG and coronary angiog-raphy. Whenever a disagreement occurred, a third observer(physician) reviewed the images, and the differences wereresolved by consensus. The duration of time for imageacquisition for all views was measured.

    Patients were fully informed about all of the tests, includ-ing their usefulness, limitations, and possible complications,and informed consent was obtained from all.

    Statistical Analysis

    All measured values are expressed as means SD. Thesensitivity, specificity, and diagnostic accuracy of exerciseECG and EchoCG-HCU were compared using the 2 test andFisher direct probability calculations. Heart rates and bloodpressures were compared using Student t test. Values of Pless than .05 were considered significant.

    RESULTS

    Of the 97 patients who underwent exercise ECG andexercise EchoCG-HCU, 6 were excluded from analysisbecause of the poor image quality of their EchoCGfindings. Of the 91 remaining patients, 58 underwentcoronary angiography within 2 weeks after their exer-cise test. The patient backgrounds are shown in Table:

    Table Patient characteristics

    Male:female 42:16Site of coronary artery stenosis

    LAD 14LCX 9RCA 7

    Single-vessel disease 10Multivessel disease 9Coronary risk factor (%)

    DM 14 (24)HT 43 (74)Hyperlipidemia 18 (31)Smoking 16 (28)

    Drug therapy (%)-blockers 13 (22)Ca antagonists 29 (50)Nitrates 8 (14)ACE-I 10 (17)ARB 12 (21)Antiplatelet agents 18 (31)Statins 15 (26)

    Ca, Calcium; ACE-I, angiotensin-converting enzyme inhibitors; ARB, an-giotensin receptor blockers; DM, diabetes mellitus; HT, hypertension; LAD,left anterior descending coronary artery; LCX, left circumflex artery; RCA,right coronary artery.

    10 had 1-vessel disease, 9 had multivessel disease, and

    39 had no significant stenosis. The stenotic sites werewithin the left anterior descending coronary artery in14 patients, the left circumflex artery in 9 patients, andthe right coronary artery in 7 patients. Exercise wasended because of leg fatigue in 22 patients (37.9%),ECG changes in 5 patients (8.6%), chest pain in 3patients (5.2%), dyspnea in 1 patient (1.7%), and theachievement of the target heart rate in 28 patients(48.3%). Heart rates were significantly increased byexercise (74 15-143 22/min; P .01), as wereboth the systolic and diastolic blood pressures (138 21-200 23 mm Hg and 79 19-84 20 mm Hg,respectively; P .01).

    Among the 19 patients with CAD, wall-motionabnormalities were detected with exerciseEchoCG-HCU in 13, and significant ECG changeswere observed in 12. Conversely, among the 39patients without CAD, wall-motion abnormalitieswere not detected with exercise EchoCG-HCU in35, and significant ECG changes were not ob-served in 28. Thus, the sensitivity, specificity, anddiagnostic accuracy of exercise ECG in the diag-nosis of CAD were 63% (12/19), 72% (28/39), and69% (40/58), respectively. When wall motion wasevaluated using an HCU device in the diagnosis ofCAD, the sensitivity, specificity, and diagnosticaccuracy were 68% (13/19), 90% (35/39), and 83%(48/58), respectively. Note that the specificitywas significantly higher with EchoCG-HCU (P .05) (Figure). When diagnosing CAD, the sensitiv-ity of EchoCG-HCU was 60% (6/10) among pa-tients with 1-vessel disease and 78% (7/9) amongthose with multivessel disease; with respect to theaffected coronary artery, the sensitivities were71%, 56%, and 71% for the left anterior descend-ing, left circumflex, and right coronary arteries,respectively. The time required to start recordingusing the HCU device was 15 5 seconds, and thetotal time required to record images for all views

    Figure Sensitivity, specificity, and diagnostic accuracy ofexercise electrocardiography (ECG) and exercise echocar-diography (Echo) using hand-carried ultrasound.

    was 40 7 seconds.

  • Journal of the American Society of Echocardiography538 Hirano et al May 2006

    DISCUSSION

    Exercise ECG has long been used to diagnoseCAD, although its diagnostic accuracy is not high.Gianrossi et al14 performed a meta-analysis involv-ing 147 studies (24,074 patients) and reportedthat the sensitivity and specificity of exercise ECGin the diagnosis of CAD were 68% and 77%,respectively. Exercise EchoCG is another tech-nique available for noninvasively detecting CADand has been shown to be more accurate thanexercise ECG.2-4 In Japan, however, exercise ECGis still used to diagnose CAD because a standardEchoCG machine is often too large to be placed inthe small exercise rooms and because standardEchoCG machines are often being used for routineexamination, making them unavailable for exer-cise EchoCG. On the other hand, Rugolotto et al5

    recently reported that an HCU device is adequatefor focused assessment of cardiac anatomy andfunction, and Spencer et al6 demonstrated that thecombination of physical examination and the find-ings on an HCU device is

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