Scintigraphic and electrocardiographic evidence of silent coronary artery disease in asymptomatic hypertension: a case-control study

Screening for Cardiovascular Disease Risk With Resting or Exercise Electrocardiography: Evidence Report and Systematic Review for the US Preventive Services Task Force

IMPORTANCE

Cardiovascular disease (CVD) is the leading cause of death in the United States.

OBJECTIVE

To review the evidence on screening asymptomatic adults for CVD risk using electrocardiography (ECG) to inform the US Preventive Services Task Force.

DATA SOURCES

MEDLINE, Cochrane Library, and trial registries through May 2017; references; experts; literature surveillance through April 4, 2018.

STUDY SELECTION

English-language randomized clinical trials (RCTs); prospective cohort studies reporting reclassification, calibration, or discrimination that compared risk assessment using ECG plus traditional risk factors vs traditional risk factors alone. For harms, additional study designs were eligible. Studies of persons with symptoms or a CVD diagnosis were excluded.

DATA EXTRACTION AND SYNTHESIS

Dual review of abstracts, full-text articles, and study quality; qualitative synthesis of findings.

MAIN OUTCOMES AND MEASURES

Mortality, cardiovascular events, reclassification, calibration, discrimination, and harms.

RESULTS

Sixteen studies were included (N = 77 140). Two RCTs (n = 1151) found no significant improvement for screening with exercise ECG (vs no screening) in adults aged 50 to 75 years with diabetes for the primary cardiovascular composite outcomes (hazard ratios, 1.00 [95% CI, 0.59-1.71] and 0.85 [95% CI, 0.39-1.84] for each study). No RCTs evaluated screening with resting ECG. Evidence from 5 cohort studies (n = 9582) showed that adding exercise ECG to traditional risk factors such as age, sex, current smoking, diabetes, total cholesterol level, and high-density lipoprotein cholesterol level produced small improvements in discrimination (absolute improvements in area under the curve [AUC] or C statistics, 0.02-0.03, reported by 3 studies); whether calibration or appropriate risk classification improves is uncertain. Evidence from 9 cohort studies (n = 66 407) showed that adding resting ECG to traditional risk factors produced small improvements in discrimination (absolute improvement in AUC or C statistics, 0.001-0.05) and appropriate risk classification for prediction of multiple cardiovascular outcomes, although evidence was limited by imprecision, quality, considerable heterogeneity, and inconsistent use of risk thresholds used for clinical decision making. Total net reclassification improvements ranged from 3.6% (2.7% event; 0.6% nonevent) to 30% (17% event; 19% nonevent) for studies using the Framingham Risk Score or Pooled Cohort Equations base models. Evidence on potential harms (eg, from subsequent angiography or revascularization) in asymptomatic persons was limited.

CONCLUSIONS AND RELEVANCE

RCTs of screening with exercise ECG found no improvement in health outcomes, despite focusing on higher-risk populations with diabetes. The addition of resting ECG to traditional risk factors accurately reclassified persons, but evidence for this finding had many limitations. The frequency of harms from screening is uncertain.

Gender aspects on exercise-induced ECG changes in relation to scintigraphic evidence of myocardial ischaemia

BACKGROUND

This retrospective study aimed to determine the diagnostic performance of exercise-induced ST response in relation to findings by myocardial perfusion single photon emission computed tomography (MPS), with focus on gender differences, in patients with suspected or established stable ischemic heart disease.

METHODS

MPS findings of 1 021 patients (518 females) were related to the exercise-induced ST response alone (blinded and unblinded to gender) and ST response together with additional exercise stress test (EST) variables (exercise capacity, blood pressure and heart rate response).

RESULTS

Exercise-induced ischaemia by MPS was found in 9% of females and 23% of males. Diagnostic performance of exercise-induced ST response in relation to MPS findings in females versus males was: sensitivity = 48%,70%; specificity = 67%, 64%; PPV = 13%, 38%; NPV = 93%, 87%. Adding more EST variables to the ST response interpretation yielded in females vs males: sensitivity = 44%, 51%; specificity = 84%, 83%; PPV = 22%, 48% and NPV = 93%, 85%.

CONCLUSIONS

In patients who have performed EST in conjunction with MPS, there is a gender difference in the diagnostic performance of ST response at stress, with a significantly lower PPV in females compared to males. For both genders, specificity can be significantly improved, and a higher PPV can be obtained, while the sensitivity might be compromised by considering more EST variables, in addition to the ST response.

Stress-induced ST elevation with or without concomitant ST depression is predictive of presence, location and amount of myocardial ischemia assessed by myocardial perfusion SPECT, whereas isolated stress-induced ST depression is not

BACKGROUND

Evaluation of stress-induced ST deviations constitutes a central part when interpreting the findings from an exercise test. The aim of this analysis was to assess the pathophysiologic correlate of stress-induced ST elevation and ST depression with regard to presence, amount and location of myocardial ischemia as assessed by myocardial perfusion SPECT (MPS) in patients with suspected coronary artery disease.

METHODS AND RESULTS

226 patients who had undergone bicycle stress test in conjunction with MPS were included. Of these, 198 were consecutive patients while 28 patients were included on the basis of having stress-induced ST elevation mentioned in their clinical report. The amount and location of ST changes were related to MPS findings. Summed stress scores (SSS) from MPS images were used to measure the amount of stress-induced ischemia. The positive predictive values for detecting stress-induced ischemia were 28% for the consecutive patients with ST depression and 75% for patients with ST elevation. The maximum and sum of stress-induced ST elevations correlated with SSS (r(2)=0.58, p<0.001 and r(2)=0.73, p<0.001), whereas the maximum and sum of significant ST depressions did not (r(2)=0.022, p=0.08 and r(2)=0.024, p=0.10). The location of ST elevation corresponded to the location of ischemia by MPS (kappa=1.0), whereas the location of ST depression did not (kappa=0.20).

CONCLUSIONS

Stress-induced ST elevation, with or without concomitant ST depression, is predictive of the presence, amount and location of myocardial ischemia assessed by MPS, whereas stress-induced ST depression without concomitant ST elevation is not.

Waist circumference and metabolic syndrome: the risk for silent coronary artery disease in males

BACKGROUND

Waist circumference (WC) is a component used to define metabolic syndrome. However, its role as an independent predictor of silent coronary artery disease (CAD), above its contribution to metabolic syndrome, remains unknown.

METHODS

Male veterans without known CAD, undergoing cardiac stress testing for indications other than typical angina or its equivalent, were evaluated for the presence of silent CAD. High WC and metabolic syndrome were defined per the revised National Cholesterol Education Program (NCEP-R) and the International Diabetes Federation (IDF) criteria.

RESULTS

Data on 1,071 patients (age 61±11 years) were analyzed retrospectively. On multivariable logistic regression analysis [odds ratio (OR), 95% confidence interval (CI), P value), a WC ≥94 cm (1.42, 1.04-1.93; P=0.026), metabolic syndrome by NCEP-R (1.73, 1.29-2.33; P<0.0001), and metabolic syndrome by IDF (1.57, 1.17-2.11; P=0.003) were independent predictors of silent CAD. When comparing patients meeting criteria for metabolic syndrome defined by either NCEP-R or IDF, the prevalence of silent CAD was not statistically different (P=0.86). The prevalence of silent CAD associated with a high WC was not inferior to that seen between silent CAD and metabolic syndrome as defined by either criterion. Last, among patients with metabolic syndrome defined by NCEP-R, those with a high WC as a defining component of metabolic syndrome had a higher prevalence of silent CAD (30% vs. 20%; P=0.026).

CONCLUSION

A WC ≥94 cm in males is independently associated with an increased prevalence of silent CAD. In patients with metabolic syndrome, this prevalence is increased by the presence of high WC.

Myocardial perfusion scintigraphy and echocardiography for detecting coronary artery disease in hypertensive patients: a meta-analysis

PURPOSE

This meta-analysis summarized the accuracy of stress myocardial perfusion scintigraphy (MPS) and stress echocardiography for the diagnosis of coronary artery disease (CAD) in patients with arterial hypertension.

METHODS

We searched for studies in which stress MPS or stress echocardiography were performed to detect CAD in hypertensive patients, with coronary angiography used as the reference test, published from January 1980 to December 2010. Studies performed in patients with known CAD, acute coronary syndrome and previous revascularization procedures were excluded.

RESULTS

Of 1,263 studies, 13 met the inclusion criteria. Pooled summary estimates showed that stress MPS had a sensitivity of 0.90 [95% confidence interval (CI) 0.82-0.95] and a specificity of 0.63 (95% CI 0.53-0.72). For stress MPS, the area under the curve (AUC) at the summary receiver-operating characteristic (SROC) graph was 0.83 (95% CI 0.80-0.86). At meta-regression analysis, the presence of positive stress electrocardiography as inclusion criterion was the only significant effect modifier (p < 0.01). Pooled summary estimates showed that stress echocardiography had a sensitivity of 0.77 (95% CI 0.69-0.83) and a specificity of 0.89 (95% CI 0.83-0.93). For stress echocardiography, the AUC at SROC was 0.91 (95% CI 0.88-0.93). At the meta-regression analysis no significant effect modifier was detected.

CONCLUSION

MPS has high sensitivity for detecting CAD in hypertensive patients, with specificity comparable to that reported in the general population, whereas stress echocardiography shows higher specificity but substantially reduced sensitivity compared to MPS.

Hypertension and myocardial ischemia

Detailed studies over the past 30 years have built up an impressive evidence base for the presence of myocardial ischemia in patients who have hypertension. This relationship ranges from the obvious association with obstructive coronary artery disease to mechanisms related to hemodynamic, microcirculatory, and neuroendocrine abnormalities. All of these factors serve to destabilize the critical balance between myocardial oxygen supply and demand. We have at our disposal a range of sophisticated investigations that allow us to demonstrate the presence and extent of the ischemia and therefore to target specific therapies to reduce the risk to these patients. Achieving target BP and managing all reversible components of the patient's cardiovascular risk status reduce to a minimum the clinical sequelae of myocardial ischemia in this vulnerable population..

Silent myocardial ischemia: Recent developments

Silent myocardial ischemia is now in its fourth decade of recognition as a clinical syndrome within the spectrum of coronary artery disease. Prior decades have seen important research into the pathophysiology, detection, prevalence, prognosis, and therapy of this syndrome. More recent developments have continued to add data to each of these areas, with particular emphasis on the comparative value of various diagnostic procedures and the effect of therapy on prognosis. While controversy still exists concerning proper screening guidelines for the asymptomatic population, there is a growing consensus that some form of stress testing in high-risk individuals (ie, those with multiple coronary risk factors) is appropriate.

Exercise versus recovery electrocardiography for predicting outcome in hypertensive patients with chest pain

BACKGROUND

Exercise electrocardiography has limited prognostic accuracy in hypertensives because of unsatisfactory specificity. We prospectively used comparative stress-recovery heart rate-adjusted ST (ST/HR) analysis to predict mortality in a consecutive population of hypertensives with chest pain.

METHODS

The stress-recovery index (SRI), defined as the difference between ST/HR areas during exercise and recovery, was derived in 460 hypertensive with known (n=360, 78%) or suspected (n=100, 22%) coronary artery disease. To assess whether it added prognostic information to routinely obtained information, clinical data, the resting ejection fraction, and exercise testing data were entered into a sequential Cox's model; the SRI was entered last. Model validation was performed by bootstrap adjusted by the degree of optimism in estimates. Survival analysis was performed using the product-limit Kaplan-Meier method.

RESULTS

During a median follow-up of 28 months (interquartile range, 13-44 months), 32 (7%) patients died, 23 (5%) suffered from acute myocardial infarction and 60 (13%) underwent late (> 3 months) revascularization. Male gender (hazard ratio, 1.53; 95% confidence interval, 1.01-2.34), peak double product (hazard ratio, 0.70; 95% confidence interval, 0.54-0.90) and the SRI (hazard ratio, 0.69; 95% confidence interval, 0.59-0.81 for interquartile difference) were independent predictors of outcome. The SRI increased the prognostic power of the model on top of clinical and exercise testing variables (concordance index, + 10%; discrimination index, + 32%) and showed the widest area under the ROC curve to predict outcome as compared with exercise-only ST analysis and the ST/HR index. Moreover, it provided a significant discrimination of survival.

CONCLUSIONS

The SRI predicts all-cause mortality in hypertensive patients with chest pain and provides additional prognostic information over clinical and standard exercise testing data.

Comparison of the predictive value of exercise-induced ST depression versus exercise technetium-99m sestamibi single-photon emission computed tomographic imaging for detection of coronary artery disease in patients with left ventricular hypertrophy

Scant knowledge exists regarding the significance of either additional ST depression in the presence of baseline depression or new stress-induced ST depression in patients with left ventricular (LV) hypertrophy. Accordingly, the purpose of this investigation is to determine whether the appearance and/or severity of ST abnormalities during exercise stress testing can accurately predict the prevalence of ischemic burden as measured by quantitative technetium-99m-sestamibi single-photon emission computed tomographic imaging in patients with LV hypertrophy. The results show that the presence of exercise ST-segment depression, as well as its magnitude, are not accurate predictors for identifying patients with coronary artery disease in the presence of electrocardiographic criteria for LV hypertrophy.

Diagnostic value of exercise electrocardiography and dipyridamole stress echocardiography in hypertensive and normotensive chest pain patients with right bundle branch block

OBJECTIVES

Studies on the diagnostic value of exercise electrocardiography in right bundle branch block produced controversial results, and data on the accuracy of stress echo are still lacking. The aim of the study was to compare the diagnostic value of exercise electrocardiography and dipyridamole stress echo in chest pain patients with right bundle branch block, and to verify whether stress testing accuracy is affected by history of hypertension.

METHODS

The study group was made up of 71 patients (56 men, aged 63 +/- 8 years) with chest pain of unknown origin and complete right bundle branch block. Of them, 35 were hypertensives and 36 normotensives. Patients performed, on different days and in random order, exercise electrocardiography and dipyridamole stress echo and underwent coronary angiography.

RESULTS

Significant (> or = 70% diameter stenosis) coronary artery disease was found in 34 patients (17 hypertensives and 17 normotensives). Positive exercise electrocardiography (ST-segment shift > 1 mm at 80 ms after the J point in leads V5 and V6 or leads II and Vf) and dipyridamole stress echo (new wall motion abnormalities) were observed in 38 and 30 patients, respectively. The result of tests was concordant in 69% of hypertensives and 92% of normotensives. The two tests shared the same sensitivity in hypertensives (82%) and normotensives (71%). Of 37 patients without coronary artery disease, 12 had a false-positive result during exercise electrocardiography and four during stress echo. The specificity was lower for exercise electrocardiography than for stress echo in hypertensives (50 versus 89%, P = 0.0006), while no difference was evidenced in normotensives (84 versus 89%, P = 0.4). In hypertensives, the accuracy, positive, and negative predictive values were 66, 61, and 75% for exercise electrocardiography, and 86, 87, and 84% for stress echo. Corresponding figures in normotensives were 78, 80, and 76% for exercise electrocardiography, and 81, 86, and 77% for stress echo.

CONCLUSIONS

In chest-pain patients with right bundle branch block, dipyridamole stress echo was effective to diagnose coronary artery disease in both normotensives and hypertensives. Moreover, it exhibited superior diagnostic information than exercise electrocardiography in hypertensives, due to significantly higher specificity. However, the two tests had similar diagnostic value in normotensives.

Clinical, exercise electrocardiographic, and pharmacologic stress echocardiographic findings for risk stratification of hypertensive patients with chest pain

Exercise electrocardiography (ECG) is of limited usefulness in hypertensive patients, whereas pharmacologic stress echocardiography can provide diagnostic and prognostic information. The aim of this study was to compare the prognostic value of clinical data, exercise ECG, and pharmacologic stress echocardiography in hypertensive patients with chest pain and to identify the best strategy for their risk stratification. Three hundred sixty-seven hypertensive patients (189 men, age 61 +/- 9 years) with chest pain of unknown origin underwent exercise ECG and pharmacologic stress echocardiography (237 with dipyridamole and 130 with dobutamine) and were followed up for 31 +/- 24 months. Positive exercise ECG (ST-segment shift of > or =1 mm at 80 ms after the J point) and stress echocardiography (new wall motion abnormalities) were found in 130 (35%) and 86 (23%) patients, respectively. During follow-up, there were 13 deaths and 16 myocardial infarctions. Additionally, 43 patients underwent coronary revascularization and were censored accordingly. Of 12 clinical, electrocardiographic, and echocardiographic variables analyzed, a positive result of stress echocardiography was the only multivariate predictor of either death (hazard ratio [HR] 4.7, 95% confidence interval [CI] 1.5 to 14.5, p = 0.007) or hard events (death, myocardial infarction) (HR 4.1, 95% CI 1.8 to 9.3, p = 0.0009). Using an interactive stepwise procedure, stress echocardiography provided additional prognostic information to clinical evaluation and exercise ECG. However, the negative predictive value of the 2 tests was similarly (p = NS) high in assessing 4-year event-free survival. In conclusion, a negative exercise electrocardiographic test identifies low-risk hypertensive patients with chest pain and should be the first-line approach for risk stratification. In contrast, positive exercise ECG is unable to distinguish between patients with different levels of risk. In this case, stress echocardiography provides strong and incremental prognostic power over clinical and exercise electrocardiographic data.

ST segment depression criteria and the prevalence of silent cardiac ischemia in hypertensives

The reported prevalence of silent cardiac ischemia as assessed by ambulatory electrocardiographic recording varies widely. The influence of the stringency of the analysis criteria has never been reported. We performed 24-hour, 12-lead ambulatory electrocardiographic recording in patients with hypertension but without proven coronary artery disease. The recordings were analyzed according to strict ST segment depression criteria adapted from the American College of Cardiology/American Heart Association guidelines and according to basic ST segment depression criteria adapted from studies with only concise descriptions of ambulatory electrocardiographic recording analysis. Also, we performed 24-hour ambulatory blood pressure monitoring. More than 4400 hours of ambulatory electrocardiographic recording and ambulatory blood pressure monitoring in 194 patients with hypertension were analyzed. Medication was withdrawn in 45% of the patients. The average systolic blood pressure during the day was 152+/-13 (mean+/-SD); diastolic blood pressure was 94+/-17 mm Hg. According to the basic ST segment depression criteria, we found a prevalence of silent ischemia of 11.3%, and with the strict criteria the prevalence was 5.2%. The patients who were considered positive according to the basic criteria but not according to the strict criteria (false-positive) in the majority of cases (58%) had depression of an elevated baseline ST segment. We found a lower prevalence of silent cardiac ischemia as assessed by ambulatory electrocardiographic recording than generally reported. The stringency of applied analysis criteria appear to play an important role in this outcome.

Diagnosis of myocardial ischemia in hypertensive patients

Arterial hypertension can provoke a reduction in coronary flow reserve through several mechanisms that are not mutually exclusive (i.e. epicardial coronary artery disease (CAD), left ventricular hypertrophy and structural and/or functional microvascular disease). These different targets of arterial hypertension should be explored with different diagnostic markers. In fact, stress-induced wall motion abnormalities are highly specific for angiographically assessed epicardial CAD, whereas ST segment depression and/or myocardial perfusion abnormalities are frequently found with angiographically normal coronary arteries associated with left ventricular hypertrophy and/or microvascular disease. Exercise-electrocardiography stress test can be used to screen patients with negative maximal test due to its excellent negative predictive value, which is high and comparable in normotensives and hypertensives. When exercise-electrocardiography stress test is positive (or uninterpretable or ambiguous), an imaging stress-echo test is warranted for a reliable identification of significant, prognostically malignant epicardial CAD in view of an ischemia-guided revascularization.

The potential prognostic value of ultrasonic characterization (videodensitometry) of myocardial tissue in essential arterial hypertension

BACKGROUND

Left ventricular hypertrophy (LVH) and the geometric shape of the left ventricle are well-established important risk factors for cardiovascular morbidity and mortality in the hypertensive population. Videodensitometry is an alternate echocardiographic approach to the study of myocardial structural and functional alterations in essential hypertension.

OBJECTIVES

To analyze the behavior of the ultrasonic videodensitometric parameter for various subgroups of a hypertensive population; first according to the severity of LVH (group A, without LVH; group B, with mild-to-moderate LVH; and group C, with severe LVH) and second according to geometric adaptation of left ventricle to pressure-volume overload of essential hypertension (group NG, normal geometry; group CR, concentric remodeling; group CH, concentric hypertrophy; and group EH, eccentric hypertrophy).

METHODS

For 70 male, essential hypertensive patients and 32 normotensive healthy subjects matched for age (58 +/- 7 years) and sex as controls (group N) we performed ambulatory blood pressure measurements for the evaluation of 24 h mean systolic and diastolic blood pressures, conventional two-dimensional Doppler echocardiography to evaluate left ventricular performance and left ventricular mass index, and digitization of left ventricular parasternal long-axis echocardiographic images. For regions of interest selected within the septum and the posterior wall, the mean gray levels were calculated at end-systole and end-diastole. The resulting values were used to estimate the percentage cyclic variation index (CVI).

RESULTS

The results according to left ventricular mass index were CVI for septum group N 34.7 + 16.3%; group A - 0.18 +/- 16%, group B - 13 +/- 19%, and group C - 22 +/- 12% (P < 0.001); and CVI of posterior wall, group N 38.2 +/- 15.4%, group A -0.75 +/- 16%, group B -16 +/- 16% and group C -16 +/- 13% (P< 0.001). According to left ventricular geometry CVI for septum were group NG 0.6 +/- 24%, group CR 1.9 +/- 17%; group CH - 25.4 +/- 18%, and group EH -17.1 +/- 20% (P < 0.01). CVI of posterior wall were group NH -5.8 + 24%, group CR 6.4 +/- 23%, group CH -29 +/- 20%, group EH -20 +/- 21 (P < 0.01).

CONCLUSIONS

Our results demonstrate that subjects with high left ventricular masses and those with concentric hypertrophy, which have the worst prognostic impacts, have the most significant changes in CVI. Furthermore, videodensitometric findings are quite different even among the subgroups with mild-to-moderate left ventricular hypertrophy and eccentric hypertrophy. Therefore this videodensitometric approach could provide some useful information for better definition of cardiovascular risk in hypertension.

Silent ischaemia and hypertension

For many years now, silent ischaemia has been recognized as a distinct clinical entity, and its relevance in different patient groups has been established. However, a number of basic questions have not been answered. In explaining the pathophysiology of silent ischaemia, factors affecting both the demand and the supply side are now being recognized. With the exception of certain well-defined groups, it is not clear why some patients are mostly symptomatic, while other patients are predominantly asymptomatic. There appear to be many factors influencing the ischaemic pain threshold. Studies investigating the prevalence of silent ischaemia show a remarkably high prevalence of silent ischaemia in different patient groups. Patients with hypertension but without coronary artery disease form a specific and vulnerable high-risk population that is particularly prone to silent ischaemia. Since changes at the macrovascular level are not responsible, various factors negatively influencing either cardiac supply or demand have been investigated. A reduced coronary reserve is central in explaining the increased prevalence of silent ischaemia in hypertensives. Left ventricular hypertrophy renders meaningful detection of ST segment changes difficult, but a possible solution dealing with this problem is offered by applying more stringent criteria in terms of minimal ST depression in the definition of ischaemia. The treatment of silent ischaemia is largely the same as for angina pectoris, but whether therapy should be directed at elimination of all ischaemic episodes or only of symptomatic episodes depends on further prospective work addressing this question.

Exercise echocardiography versus exercise electrocardiography in the diagnosis of coronary artery disease in hypertension

In hypertension, coronary artery disease (CAD) can be overestimated by stress electrocardiography (ECG) and scintigraphy due to frequent false-positive results. Exercise tests are also limited by an excessive blood pressure increase, and pharmacologic pressure normalization decreases the accuracy of the test. The aim of this study was to assess the accuracy of exercise echocardiography as an alternative test for CAD detection in hypertension, both before and after adequate blood pressure control. We studied 59 hypertensive and 59 normotensive patients undergoing coronary angiography for chest pain. Upright bicycle exercise ECG and echocardiographic tests were performed in each group in the absence of therapy; in hypertensives, the tests were repeated a day apart after blood pressure normalization with sublingual nifedipine. Significant CAD (lumen narrowing >50%) was detected in 22 hypertensive and 41 normotensive patients. In the two groups, sensitivity, specificity, and diagnostic accuracy of exercise echocardiography performed before treatment were not statistically different (95%, 94%, 94% in hypertensives and 82%, 77%, 83% in normotensives, respectively), but were significantly higher than for the exercise ECG test (68%, 70%, and 69%, respectively). After blood pressure lowering, exercise echocardiography sensitivity slightly decreased (91%), whereas specificity (100%) and diagnostic accuracy (96%) did not vary; on the contrary, exercise ECG sensitivity decreased to 45%. Therefore, according to our data, exercise echocardiography can be an accurate test and more reliable than exercise ECG to detect CAD in normotensives as well as in hypertensives. Normalization of blood pressure with nifedipine does not affect its accuracy, but markedly reduces the sensitivity of exercise ECG.

Is rest or exercise hypertension a cause of a false-positive exercise test?

STUDY OBJECTIVES

To determine if a history of hypertension or an exaggerated rise in exercise systolic BP is associated with a false-positive exercise ECG.

DESIGN, SETTING, AND PATIENTS

Retrospective analysis of the associations between exercise-induced ST-segment depression and a history of hypertension, exercise systolic BP, and several other clinical and exercise test variables. Among 20,097 patients referred for exercise tomographic thallium imaging in a nuclear cardiology laboratory at a tertiary care center, 1,873 patients met inclusion criteria for this study, which included no history of myocardial infarction or coronary artery revascularization, a normal resting ECG, and normal exercise thallium images.

RESULTS

False-positive ST-segment depression occurred in 20% of the population. A history of hypertension was actually associated with a lower likelihood of ST-segment depression (odds ratio, 0.70; 95% confidence interval [CI], 0.55 to 0.89; p = 0. 004). A higher peak exercise systolic BP was associated with a higher likelihood of ST-segment depression (odds ratio, 1.08 for each 10-mm Hg increase in systolic BP; 95% CI, 1.03 to 1.14; p < 0. 001). However, the association between peak exercise systolic BP and ST-segment depression was so weak that this measurement could not be predictive in the individual patient (R(2) = 0.2%). For every 20-mm Hg increase in peak exercise systolic BP, the percentage of patients with ST-segment depression increased by only 3%.

CONCLUSIONS

In patients with normal resting ECGs, we conclude the following: (1) a history of hypertension is not a cause of a false-positive exercise test, and (2) higher exercise systolic BP is a significant but weak predictor of ST-segment depression.

Dipyridamole stress echocardiography for risk stratification in hypertensive patients with chest pain

BACKGROUND

The noninvasive prognostic assessment of coronary artery disease (CAD) in hypertensive patients represents an unresolved task to date. In this study, we investigated the value of dipyridamole stress echocardiography in risk stratification of hypertensive patients with chest pain and unknown CAD.

METHODS AND RESULTS

Dipyridamole stress echocardiography was performed in 257 hypertensives (110 men; age, 63+/-9 years) complaining of chest pain and without a history of CAD. No major complications occurred. Four tests were interrupted prematurely because of side effects, with 98. 4% feasibility of test. A positive echocardiographic response was found in 72 patients (27 during the low-dose [</=0.56 mg/kg] and 45 during the high-dose [>0.56 mg/kg]). During the follow-up (32+/-18 months), 27 cardiac events occurred: 3 deaths, 8 infarctions, and 16 cases of unstable angina. Moreover, 27 patients underwent coronary revascularization. At multivariate analysis, the positive echocardiographic result (OR, 5.5; 95% CI, 1.4 to 16.6) was the only predictor of hard cardiac events (death, infarction). Considering spontaneous cardiac events (death, infarction, and unstable angina) as end points, the positive echocardiographic result (OR, 4.2; 95% CI, 1.8 to 9.6) and family history of CAD (OR, 4.2; 95% CI, 1.5 to 6. 9) were independently associated with prognosis. The 3-year survival rates for the negative and the positive populations were, respectively, 97% and 87% (P=0.0019) considering hard cardiac events and 96% and 74% (P=0.0000) considering spontaneous cardiac events.

CONCLUSIONS

Dipyridamole stress echocardiography is safe, highly feasible, and effective in risk stratification of hypertensives with chest pain and unknown CAD. At present, it represents an attractive option for prognostic assessment of this clinically defined population.

Hypertension and coronary artery disease

Hypertension is one of the major risk factors for coronary artery disease. This risk is considerably magnified by the presence of left ventricular hypertrophy. The likeliest dominant factor in this increased risk is myocardial ischaemia, the recognition of which is of key importance. Antihypertensive agents ideally should also protect against occurrence of the clinical syndromes associated with coronary artery disease.