The clinical role of stress myocardial perfusion imaging in women with suspected coronary artery disease

Cardiovascular disease remains the number one cause of mortality for women in the United States, with coronary artery disease (CAD) accounting for 54% of all cardiovascular deaths. CAD claims the lives of more than 250,000 women each year and is therefore the single largest killer of American women. For several decades, the underrepresentation of women in clinical trials led to both a lack of available sex-specific evidence and a generalized misconception that CAD was a “man's disease.” In actuality, not only are women vulnerable to CAD, they typically develop it 10 to 15 years later than men. Furthermore, sex differences exist in the mortality rates of women and men with CAD, such that once CAD is present in women, they have worse outcomes than their male counterparts. Consequently, early and accurate diagnosis of CAD is crucial for reducing mortality rates in women. Stress myocardial perfusion imaging (MPI) using contemporary techniques has been shown to have significant value in the diagnosis and prognosis of CAD in women. In the risk assessment of women with an intermediate clinical pretest likelihood of CAD, using MPI with exercise or pharmacologic stress has been shown to add incremental value to clinical variables or exercise electrocardiogram stress testing alone. This review discusses the clinical role of stress MPI in the management of women with suspected CAD.     

The role of myocardial perfusion imaging in the diagnosis of patients with coronary artery disease: developments over the past year

PURPOSE OF REVIEW: The role of myocardial perfusion imaging in the diagnosis of coronary artery disease in various patient populations has been expanding. Recent literature from March 2004 to February 2005 has advanced the concept of attenuation correction and electrocardiographic gating in improving the diagnosis of coronary artery disease. RECENT DEVELOPMENTS: The American Heart Association encourages the use of electrocardiographic-gated single photon emission computerized tomography in women. Asymptomatic diabetic patients may benefit from screening with myocardial perfusion imaging. Dobutamine stress perfusion imaging is an important diagnostic tool in elderly patients who are unable to exercise. In patients with chest pain, acute imaging may decrease unnecessary admissions. Vasodilator stress imaging has high sensitivity and specificity in patients with left bundle branch block. Patients undergoing endovascular stent grafting may benefit from risk stratification with vasodilator myocardial perfusion imaging. The American Society of Nuclear Cardiology and the Society of Nuclear Medicine have recognized the role of attenuation correction in increasing the diagnostic accuracy of myocardial perfusion imaging. Multiple studies emphasize the importance of electrocardiographic gating in myocardial perfusion imaging. SUMMARY: Recent developments have resulted in an important statement by the American Heart Association that assigns a larger role for myocardial perfusion imaging in the diagnosis of coronary artery disease in women. The role of myocardial perfusion imaging is also expanding in various other patient populations. The literature has validated the concept of attenuation correction for the accurate assessment of attenuation artifacts as well as electrocardiographic gating in enhancing the diagnosis and risk stratification for coronary artery disease.     

Value of gated SPECT myocardial perfusion imaging for individual cardiac risk assessment

Myocardial perfusion imaging enables not only accurate diagnosis of disease but also entails prognostic value. Myocardial perfusion SPECT contributes to assessment of future cardiac events independently of other clinical parameters. A normal stress myocardial perfusion scan is associated with a favorable prognosis independent of history, symptoms, and exercise electrocardiography test variables. Cardiac risk and benefit from invasive therapeutic strategies increase in relation to the severity of the abnormality of perfusion and function assessed by gated myocardial perfusion SPECT. Thus, stress myocardial perfusion imaging may serve as a gatekeeper for referral to coronary angiography enabling effective risk stratification in patients with suspected or documented coronary artery disease.     

The noninvasive prediction of cardiac mortality in men and women with known or suspected coronary artery disease. Economics of Noninvasive Diagnosis (END) Study Group

PURPOSE: The association between myocardial perfusion imaging defects and cardiac mortality in women is undefined. We examined whether myocardial perfusion imaging predicted cardiac mortality in men and women and compared this with other variables influencing prognosis. SUBJECTS AND METHODS: Six academic institutions with high-volume nuclear cardiology laboratories consecutively studied 5,009 men aged 62 +/- 12 years (mean ISD) and 3,402 women aged 66 +/- 11 years with symptomatic known or suspected coronary artery disease undergoing exercise (n = 7,486) or pharmacologic stress (n = 925) myocardial perfusion imaging. A pretest clinical risk index was calculated from age, history of myocardial infarction, diabetes, hypertension, and hypercholesterolemia. Myocardial perfusion images were analyzed for stress-induced defects or any defect in the territories of the three major coronary arteries. RESULTS: Stress-induced perfusion defects were seen in 39% of men and 25% of women (P = 0.0001). Extensive stress-induced or fixed defects (>2 vascular territories) were less common in women than men (10% vs 19%, and 4% vs 18%, both P = 0.0001). During a mean of 2.4 +/- 1.5 years of follow-up, 143 patients died of cardiac causes. The clinical risk index and number of territories with perfusion defects were associated with cardiac mortality in women and men. In women undergoing exercise myocardial perfusion imaging, the number of abnormal territories remained the strongest correlate of mortality after adjustment for exercise variables. CONCLUSIONS: The results of myocardial perfusion imaging are important, independent predictors of survival in both women and men.     

ATP负荷及运动负荷试验中心电图的变化对冠心病的诊断价值

目的探讨ATP负荷及运动负荷心肌灌注单光子发射计算机体层摄影术(SPECT)中的ECG变化及其对冠心病的诊断价值。方法选择61例疑诊冠心病的患者,并在不同时间分别行ATP负荷及运动负荷SPECT检查,其中46例行冠状动脉造影。收集ATP及运动负荷试验中的ECG资料并进行分析。结果ATP与运动负荷试验中ECG心律失常的发生情况相似(χ2=1.985,P=0.159);ATP负荷试验ST段下降发生率明显低于运动负荷试验(12.5%vs51.8%,χ2=19.813,P<0.001),且下降幅度低。ATP负荷试验ECG诊断冠心病的敏感性明显低于运动负荷试验(28.6%vs71.4%,χ2=7.714,P=0.005),特异性、阳性预测值及阴性预测值与运动负荷试验相似(95.2%vs71.4%,85.7%vs71.4%,57.1%vs71.4%,P>0.05)。结论与运动负荷试验比较,ATP负荷试验ECG诊断冠心病的敏感性低,但特异性及阳性预测值相对较高。     

Exercise electrocardiogram testing and imaging in women

The increased awareness of the incidence and risk of coronary heart disease (CHD) has increased the efforts of physicians to identify women with CHD as early as possible. Exercise electrocardiogram (ECG) testing and imaging have been used in this manner for men and women but represent unique challenges with regard to women. Exercise ECG testing, which determines the presence of coronary artery disease by the provocation of ST depression and chest pain, has a lower positive predictive value in women than in men of the same age. This is explained by a lower prevalence of CHD in female patients with symptoms and (to a lesser extent) by the reported lower sensitivity and specificity of the test in women as compared with men. Exercise nuclear isotope myocardial perfusion imaging and exercise echocardiography have higher reported specificity and sensitivity, and new imaging agents, contrast echo agents, and acquisition protocols have reduced the limitations of these studies in selected women. The value of the exercise ECG examination with regard to CHD event risk assessment is equal in men and women and should be incorporated into the clinical evaluation of appropriate women patients.     

锝-氮-氮欧乙替心肌灌注显像对冠心病的诊断评价

目的评价锝-氮-氮欧乙替（^99mTc-N—NOET）心肌灌注显像检测冠心病的价值。方法对42例临床疑诊冠心病患者,行^99mTc-N-NOET运动负荷和再分布心肌灌注显像,所有患者行冠状动脉造影检查。结果在42例患者中,26例冠状动脉造影显示有冠状动脉狭窄病变,其中单支病变10例,二支病变7例,三支病变9例.^99mTc-N-NOET心肌显像检出心肌缺血或心肌梗死21例,未检出异常5例;16例冠状动脉造影正常患者,^99mTc-N-NOET心肌显像正常14例,异常2例.^99mTc-N-NOET心肌灌注显像诊断冠心病的敏感性为81％、特异性为88％、阳性预测值91％,阴性预测值74％,预测准确性为83％。诊断单支、二支和三支冠状动脉病变的敏感性分别为60％（6／10）、86％（6／7）、100％（9／9）。42例均无干扰心肌分辨的肺、肝重度摄取增高者。15min运动负荷显像肺脏摄取高,尤以冠状动脉狭窄患者增高明显。结论 ^99mTc-N-NOET心肌灌注显像检测冠心病敏感性、特异性较高,早期显像肺摄取增加与有意义的冠状动脉病变有关。     

腺苷负荷试验心肌核素显像对冠心病诊断价值的评估

目的分析腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性、特异性及其特点。方法住院患者同时行冠状动脉（冠脉）造影和腺苷负荷试验心肌核素显像。腺苷总量为840μg／kg,6min匀速静脉泵入,腺苷泵入3min时静脉推注^99m锝-甲氧基异丁基异腈核素显像925MBq,1．5h后进行心肌断层显像,若异常,次日行静息心肌显像。结果冠脉造影阳性50例中,心肌核素显像阳性44例。29例冠脉造影无明显狭窄,其中19例心肌核素显像阴性。腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性和特异性为88．O％和65．5％。前降支病变40例,心肌核素前壁区域低灌注32例,回旋支病变27例,侧壁区域低灌注21例,右冠脉病变32例,下壁区域低灌注31例,右冠脉病变较前降支或回旋支病变的心肌核素显像阳性率高（P〈0．05）。结论腺苷负荷试验心肌核素显像对于冠心病诊断的敏感性、特异性较高。     

Usefulness and pitfalls in myocardial perfusion SPECT for detecting and assessing coronary artery disease

Thallium-201(Tl) is the dominant agent employed for myocardial perfusion imaging for detection of coronary artery disease, assessment of myocardial viability and prognostication. Technetium-99m(Tc) labeled radionuclides have been used as excellent alternatives to Tl. This paper will review the usefulness and pitfall in myocardial perfusion single photon emission computed tomography(SPECT) in patients with coronary artery disease. From a practical standpoint, we should know what are clinical questions, clinical status of patients(history and exercise ability of patients, obesity) and diagnostic accuracy of each diagnostic protocol and the performance in the nuclear laboratory. Myocardial perfusion defects during stress SPECT are produced by a heterogeneity in coronary blood flow, which depends on severity of coronary stenosis and consequent abnormalities in flow reserve. Certain factors can affect sensitivity and specificity of Tl SPECT for detection of coronary artery disease. Accurate determination of myocardial viability is vitally important for clinical decision making for patients with left ventricular(LV) dysfunction who will most benefit from revascularization. Hibernated myocardium may result in profound regional LV dysfunction in absence of necrosis. The various approach such as stress-redistribution-reinjection imaging, rest-redistribution imaging and rest-redistribution 24 hours delayed imaging has been utilized to assess myocardial viability with Tl. Alternatively, quantitative assessment of 99mTc-methoxy-isobutyl isonitrile(MIBI) and tetrofosmin uptake reflect the degree of viability. At the present time one of the most important clinical applications of exercise myocardial perfusion SPECT is the assessment of prognosis for patients with suspected and documented coronary artery disease. Patients with normal stress perfusion SPECT have a low event rate and excellent prognosis. Stress perfusion imagings have been widely used to stratify patients into different risk groups in the United State.     

腺苷负荷试验心肌灌注显像诊断冠心病的临床价值

目的　评价腺苷负荷试验心肌灌注显像诊断冠心病的准确性。方法　对 89例临床疑诊冠心病患者 ,分别静脉注射腺苷 ,剂量为 14 0 μg·kg-1·min-1,用药时间 6min(总剂量为 0 8mg/kg) ,注射过程中 ,行心电监测 ,观察患者的症状、血压和心率 ,于注射腺苷 3min末 ,静脉注射核素显像剂99mTc MIBI 92 5MBq ,1h后行心肌灌注断层显像 ,若显像异常 ,次日行静息心肌显像。所有患者行冠状动脉造影。结果　在 89例患者中 ,31例冠状动脉造影显示明显的冠状动脉狭窄病变 ,其中单支病变 10例 ,二支病变 11例 ,三支病变 10例。累及左前降支 2 8支 ,左回旋支 18支 ,右冠状动脉 16支 ,左主干 2支。腺苷负荷试验心肌灌注显像诊断冠心病的敏感性为 71%、特异性为 91%、阳性预测值81%、阴性预测值 84 %、准确性为 84 %。诊断单支、二支和三支冠状动脉病变患者的敏感性分别为5 0 %、73%、90 %。腺苷负荷试验心肌灌注显像判断血管病变的敏感性 77%、特异性 96 %、准确性 92 %。结论　腺苷负荷心肌灌注显像诊断冠心病敏感性及特异性均较高 ,具有重要的临床应用价值。     

Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis

Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.     

Clinical assessment of myocardial perfusion with thallium-201

Assessment of myocardial perfusion and coronary blood flow in man can be performed reliably and successfully using thallium-201 imaging. The extent of exercise myocardial perfusion abnormalities reflects the functional significance of coronary artery stenosis. Accordingly, myocardial perfusion imaging is not only useful for the detection of coronary artery disease, but it also provides unique functional information which should be helpful in the management of patients with known coronary artery disease. The unfavorable physical properties of thallium-201 have limited to a certain extent full utilization of the clinical potential of the methodology. Now technetium-99m-labeled myocardial perfusion imaging agents promise to further enhance the clinical usefulness of myocardial perfusion imaging in patients.     

Similarity between women and men in manifestation of myocardial ischemia during exercise

We assessed the effect of gender on the electrocardiographic changes and thallium-201 myocardial perfusion during exercise in patients with coronary artery disease. Eighty-nine patients with coronary artery disease (50% or greater diameter narrowing of one or more major coronary arteries) who had undergone exercise thallium scintigraphy were retrospectively studied. There were 29 women and 60 men. Fifty-six patients had one-vessel disease, 11 patients had two-vessel disease, and 22 patients had three-vessel disease or left main disease. The extent of coronary artery disease was assessed by the Gensini score. There was no difference between men and women in age, medications, number of diseased vessels and the coronary artery disease score. Exercise tolerance was lower, although insignificantly in women compared to men. However, exercise heart rate, double product, and the electrocardiographic response were similar in men and women. Also, both the presence and size of exercise-induced perfusion defects were similar in men and women. Thus, the electrocardiographic response to exercise is not influenced by gender in patients with similar extent of coronary artery disease and comparable manifestations of myocardial ischemia.     

Impact of hypertension on the accuracy of exercise stress myocardial perfusion imaging for the diagnosis of coronary artery disease

AIM—To compare the accuracy of exercise stress myocardial perfusion single photon emission computed tomography (SPECT) imaging for the diagnosis of coronary artery disease in patients with and without hypertension.
METHODS—A symptom limited bicycle exercise stress test in conjunction with 99m technetium sestamibi or tetrofosmin SPECT imaging was performed in 332 patients (mean (SD) age, 57 (10) years; 257 men, 75 women) without previous myocardial infarction who underwent coronary angiography. Of these, 137 (41%) had hypertension. Rest SPECT images were acquired 24 hours after the stress test. An abnormal scan was defined as one with reversible or fixed perfusion defects.
RESULTS—In hypertensive patients, myocardial perfusion abnormalities were detected in 79 of 102 patients with significant coronary artery disease and in nine of 35 patients without. In normotensive patients, myocardial perfusion abnormalities were detected in 104 of 138 patients with significant coronary artery disease and in 16 of 57 patients without. There were no differences between normotensive and hypertensive patients in sensitivity (77% (95% confidence interval (CI) 69% to 86%) v 75% (95% CI 68% to 83%)), specificity (74% (95% CI 60% to 89%) v 72% (95% CI 60% to 84%)), and accuracy (77% (95% CI 70% to 84%) v 74% (95% CI 68% to 80%)) of exercise SPECT for diagnosing coronary artery disease. The accuracy of SPECT was greater than electrocardiography, both in hypertensive patients (p = 0.005) and in normotensive patients (p = 0.0001). For the detection of coronary artery disease in individual vessels, sensitivity was 58% (95% CI 51% to 65%) v 57% (95% CI 51% to 64%), specificity was 86% (95% CI 82% to 90%) v 85% (95% CI 81% to 89%), and accuracy was 74% (95% CI 70% to 78%) v 74% (95% CI 70% to 78%) in patients with and without hypertension (NS).
CONCLUSIONS—In the usual clinical setting, the value of exercise myocardial perfusion scintigraphy for diagnosing coronary artery disease is not degraded by the presence of hypertension.


Keywords: hypertension; coronary artery disease; exercise stress test; myocardial perfusion     

Stress echocardiography versus myocardial SPECT for risk stratification of patients with coronary artery disease

PURPOSE OF REVIEW: Diagnostic testing using noninvasive imaging has become an integral part of risk stratification in patients with coronary artery disease. It is important to understand the integral strengths and weaknesses between the different modalities of stress testing and to apply accurately the type of test the clinical scenario demands. RECENT FINDINGS: There have been tremendous advances made in the field of cardiac imaging. Both myocardial perfusion imaging and stress echocardiographic techniques continue to evolve and play an important role in the assessment of patients with coronary artery disease. SUMMARY: In this review the authors discuss the relative merits of both stress echocardiography and myocardial single photon emission computed tomographic imaging for diagnosis and risk stratification of patients with coronary artery disease.     

Predictive importance of clinical findings and a predischarge exercise test in patients with suspected unstable coronary artery disease

The prognostic information of clinical variables and a predischarge exercise test was studied in 400 patients (282 men, 118 women) admitted to the coronary care unit with suspected unstable coronary artery disease, that is, recurring chest pain of new onset, increasing anginal pain in formerly stable angina pectoris or suspected nontransmural acute myocardial infarction. Forty-nine coronary events occurred in the 276 men who performed the exercise test during the following year, whereas only 5 coronary events occurred among the 118 women. The only variable of prognostic importance in women was nontransmural myocardial infarction. In men, the clinical variables increasing age, duration of angina, ST- or T-segment changes on the rest electrocardiogram and increasing angina or nontransmural myocardial infarction as inclusion criteria were associated with increased occurrence of coronary artery bypass surgery, transmural myocardial infarction or cardiac death. Findings of ST-segment depression, limiting chest pain or low rate-pressure product during the exercise test were of greater value than any clinical variable in prediction of coronary artery bypass surgery, transmural myocardial infarction or cardiac death. Within all clinical subgroups of men, the results of the exercise test had an additive predictive value for future coronary events. Combinations of clinical data and exercise test results enabled the best identification of patients with high or low risk for coronary events.     

Clinical Indications for Thallium-201 Myocardial Perfusion Scanning*

Abstract: Clinical indications for Thallium-201 myocardial perfusion scanning. R. F. Dunn and D. T. Kelly, Aust. N.Z. J. Med., 1982, 12, pp. 294–301. Thallium-201 myocardial perfusion scanning can assess regional myocardial perfusion noninvasive^. As it is both time-consuming and expensive its use should be restricted to specific diagnostic problems. The clinical indications in known or suspected coronary artery disease are reviewed. In suspected coronary artery disease thallium scanning is most useful in patients with chest pain when the exercise ECG is uninterpretable, in men with probable angina but a negative exercise ECG, or conversely a positive exercise ECG without typical angina, and in women with probable angina and either a positive or a negative exercise ECG. In known coronary artery disease, thallium scanning may help determine the functional significance of a coronary obstruction found at angiography and may determine the site of myocardial ischaemia when multiple obstructions are present.     

The diagnostic and prognostic value of exercise electrocardiography in asymptomatic subjects and stable symptomatic patients

In asymptomatic patients, the use of exercise ECG testing for the detection of subclinical coronary artery disease has considerable theoretical appeal, but its practical application is severely hampered by the constraints of Bayes' theorem. Serial exercise ECGs do not appear to offer significant improvement in this regard. Thallium-201 perfusion scintigraphy performed in conjunction with an exercise ECG can greatly improve the predictive value of such testing, although at considerable cost. Screening strategies with promise are those that reserve exercise testing for individuals at greater-than-average risk for subclinical coronary artery disease (eg, patients with multiple coronary risk factors) or that prescribe sequential testing, where only those with an abnormal exercise ECG are subjected to thallium-201 scintigraphy. At present, the optimal method of identifying asymptomatic individuals at high risk of a major cardiac event remains undefined. The use of maximal-effort stress testing has stood the test of time in the evaluation of patients with stable symptoms suggestive of coronary artery disease. This is particularly true when variables other than the ECG response to exercise are considered. The independent contribution of exercise angina remains controversial; however, recent studies indicate that it correlates with a more severe symptom pattern and more extensive coronary artery disease. Prognostic stratification in these studies was improved by considering both subjective and objective manifestations of ischemia. Although exercise ECG testing has been shown to have important prognostic value after acute myocardial infarction, exercise thallium-201 scintigraphy offers several potential advantages for asymptomatic post-myocardial infarction patients, several of which this paper reviews. The more optimal prognostic efficiency of thallium-201 scintigraphy is due in part to the fact that the error rate in falsely classifying patients at low risk is substantially smaller with scintigraphy than with stress electrocardiography. Because of this, there appears to be adequate rationale for recommending exercise perfusion imaging, rather than exercise ECG testing alone, as the preferred method for evaluating mortality and morbidity risks after acute myocardial infarction.     

Can exercise electrocardiography and thallium-201 myocardial imaging exclude the diagnosis of coronary artery disease?: Bayesian analysis of the clinical limits of exclusion and indications for coronary angiography

The objective of this study was to determine whether exercise electrocardiography can be combined with thallium-201 myocardial imaging and the clinical history to exclude the diagnosis of coronary artery disease. All 96 patients in this study were referred for coronary angiography because of chest pain but did not have prior myocardial infarction; 52 percent had coronary artery disease. Each patient's chest pain was classified as either typical or not typical of angina pectoris. Negative tests with inadequate exercise stress (less than 85 percent of the age-predicted maximal heart rate) and combined tests with discordant results (either exercise electrocardiography or thallium imaging positive and the other test negative) were judged nondiagnostic. Nondiagnostic tests that contributed most to the uncertainty of results were classified separately: exercise electrocardiogram, 35 patients; thallium imaging, 9 patients; and combined exercise electrocardiogram and thallium imaging, 50 patients. The ability of each test to rule out coronary artery disease was defined by its predictive error (probability of coronary disease despite a negative test): history of chest pain not typical of angina, 26 percent (11 of 42); exercise electrocardiogram, 22 percent (5 of 23); thallium imaging, 27 percent (6 of 35); and negative findings on both exercise electrocardiogram and thallium imaging, 6 percent (1 of 17). Finally, when only the patients with atypical chest pain were considered, there was zero (0 of 15) predictive error if both tests were negative.Negative exercise electrocardiography and thallium imaging during adequate stress ruled out any coronary artery disease in these patients with considerable reliability (94 percent) and excluded multivessel disease with even greater reliability. These exclusion tests for coronary artery disease were most reliable in patients in whom the clinical diagnosis of coronary artery disease was least likely, as defined by Bayes' theorem. It is concluded that there is no perfect noninvasive test to exclude coronary disease in all patient populations; however, coronary angiography is not necessary to rule out the diagnosis of coronary artery disease in patients who'have (1) no clinical indicators of a very high probability of coronary disease, such as typical angina, (2) adequate exercise stress, (3) negative exercise electrocardiogram and (4) negative exercise thallium images.     

Heart rate variability as a marker of myocardial perfusion

RR variability (HRV), an independent predictor of death following myocardial infarction, may also be related to other features of coronary artery disease. We evaluated its ability to differentiate among sedentary patients with chest pain >/=45 years of age demonstrating either normal or abnormal myocardial perfusion with rest and exercise thallium-210 tomographic imaging. The major HRV difference between 48 men and 50 women with normal perfusion was a significantly higher high frequency power in women. No significant differences in mean HRV values were found between the 57 men with abnormal perfusion scans and the 48 men with normal perfusion. In both men and women with normal perfusion scans, duration of exercise was significantly related to age. In men with abnormal scans, impaired myocardial perfusion alters the relationship between exercise duration and age, and a group of individuals with diminished HRV and low levels of physical fitness, regardless of age, can be identified. Despite these latter selective findings, we conclude that HRV is not a sensitive indicator to differentiate patients with normal and abnormal myocardial perfusion.