Is exercise testing useful to improve the prediction of coronary events in asymptomatic subjects?:

False-positive stress testing: Does endothelial vascular dysfunction contribute to ST-segment depression in women? A pilot study

BACKGROUND

The utility of exercise-induced ST-segment depression for diagnosing ischemic heart disease (IHD) in women is unclear.

HYPOTHESIS

Based on evidence that IHD pathophysiology in women involves coronary vascular dysfunction, we hypothesized that coronary vascular dysfunction contributes to exercise electrocardiography (Ex-ECG) ST-depression in the absence of obstructive coronary artery disease, so-called false positive results. We tested our hypothesis in a pilot study evaluating the relationship between peripheral vascular endothelial function and Ex-ECG.

METHODS

Twenty-nine asymptomatic women without cardiac risk factors underwent maximal Bruce protocol exercise treadmill testing and peripheral endothelial function assessment using peripheral arterial tonometry (Itamar EndoPAT 2000) to measure reactive hyperemia index (RHI). The relationship between RHI and Ex-ECG ST-segment depression was evaluated using logistic regression and differences in subgroups using 2-tailed t tests.

RESULTS

Mean age was 54 ± 7 years, body mass index 25 ± 4 kg/m2 , and RHI 2.51 ± 0.66. Three women (10%) had RHI <1.68, consistent with abnormal peripheral endothelial function, whereas 18 women (62%) met criteria for positive Ex-ECG based on ST-segment depression in contiguous leads. Women with and without ST-segment depression had similar baseline and exercise vital signs, metabolic equivalents achieved, and RHI (all P > 0.05). RHI did not predict ST-segment depression.

CONCLUSIONS

Our pilot study demonstrates high prevalence of exercise-induced ST-segment depression in asymptomatic, middle-aged, overweight women. Peripheral vascular endothelial dysfunction did not predict Ex-ECG ST-segment depression. Further work is needed to investigate the utility of vascular endothelial testing and Ex-ECG for IHD diagnostic and management purposes in women.

Screening for Cardiovascular Disease Risk With Electrocardiography: US Preventive Services Task Force Recommendation Statement

IMPORTANCE

Cardiovascular disease (CVD), which encompasses atherosclerotic conditions such as coronary heart disease, cerebrovascular disease, and peripheral arterial disease, is the most common cause of death among adults in the United States. Treatment to prevent CVD events by modifying risk factors is currently informed by CVD risk assessment with tools such as the Framingham Risk Score or the Pooled Cohort Equations, which stratify individual risk to inform treatment decisions.

OBJECTIVE

To update the 2012 US Preventive Services Task Force (USPSTF) recommendation on screening for coronary heart disease with electrocardiography (ECG).

EVIDENCE REVIEW

The USPSTF reviewed the evidence on whether screening with resting or exercise ECG improves health outcomes compared with the use of traditional CVD risk assessment alone in asymptomatic adults.

FINDINGS

For asymptomatic adults at low risk of CVD events (individuals with a 10-year CVD event risk less than 10%), it is very unlikely that the information from resting or exercise ECG (beyond that obtained with conventional CVD risk factors) will result in a change in the patient's risk category as assessed by the Framingham Risk Score or Pooled Cohort Equations that would lead to a change in treatment and ultimately improve health outcomes. Possible harms are associated with screening with resting or exercise ECG, specifically the potential adverse effects of subsequent invasive testing. For asymptomatic adults at intermediate or high risk of CVD events, there is insufficient evidence to determine the extent to which information from resting or exercise ECG adds to current CVD risk assessment models and whether information from the ECG results in a change in risk management and ultimately reduces CVD events. As with low-risk adults, possible harms are associated with screening with resting or exercise ECG in asymptomatic adults at intermediate or high risk of CVD events.

CONCLUSIONS AND RECOMMENDATION

The USPSTF recommends against screening with resting or exercise ECG to prevent CVD events in asymptomatic adults at low risk of CVD events. (D recommendation) The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening with resting or exercise ECG to prevent CVD events in asymptomatic adults at intermediate or high risk of CVD events. (I statement).

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.

Dutch Lipid Clinic Network low-density lipoprotein cholesterol criteria are associated with long-term mortality in the general population

BACKGROUND

Heterozygous familial hypercholesterolaemia (HeFH) is a severe autosomal dominant disease that is underdiagnosed, inadequately treated and has a severe long-term cardiovascular risk. Few studies have evaluated the long-term risk of high low-density lipoprotein cholesterol (LDL-C) concentrations.

AIM

To evaluate long-term mortality in a large cohort of healthy subjects, according to LDL-C concentrations.

METHODS

Based on a sample of 6956 subjects visiting a preventive cardiology department, we selected adult subjects without a personal history of cardiovascular disease. From 1995 to 2011, 4930 healthy subjects were examined and followed up until 31 December 2011. All-cause deaths were collected exhaustively. A Cox-based multivariable analysis evaluated long-term total mortality risk according to Dutch Lipid Clinic Network (DLCN) LDL-C concentrations.

RESULTS

After a mean follow-up of 8.6 years, 123 all-cause deaths were recorded (cumulative mortality rate, 2.5%). In the final multivariable model, major risk factors such as age, sex, tobacco use and diabetes were significantly associated with mortality. After adjustment for age, sex, tobacco use, hypertension, diabetes and statin therapy, and in comparison with subjects with LDL-C<4 mmol/L (<155 mg/dL), subjects with LDL-C between 4 and <5 mmol/L (155 to <190 mg/dL) had a hazard ratio (HR) of 1.99 (95% confidence interval [CI] 1.31-3.02; P=0.001), subjects with LDL-C between 5 and <6.5 mmol/L (190 to <250 mg/dL) had an HR of 1.81 (95% CI, 1.06-3.02; P=0.030), subjects with LDL-C between 6.5 and<8.5 mmol/L (250 to <330 mg/dL) had an HR of 2.69 (95% CI, 1.06-6.88; P=0.038) and subjects with LDL-C ≥ 8.5 mmol/L (≥330 mg/dL) had an HR of 6.27 (95% CI, 0.84-46.57; P=0.073). After excluding patients on statins at baseline, subjects with LDL-C ≥ 8.5 mmol/L (≥330 mg/dL) had an HR of 8.17 (95% CI, 1.08-62.73; P=0.042).

CONCLUSIONS

The severity of LDL-C elevation is associated with a higher risk of death in healthy subjects. DLCN LDL-C concentrations may be used in daily practice to identify patients with HeFH who warrant aggressive treatment.

The Total Joint Arthroplasty Cardiac Risk Index for Predicting Perioperative Myocardial Infarction and Cardiac Arrest After Primary Total Knee and Hip Arthroplasty

BACKGROUND

Current indices fail to consistently predict risk for major adverse cardiac events after major total joint arthroplasty.

METHODS

All primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) were identified from the National Surgical Quality Improvement Program data set. Based on prior analyses, age ≥80 years, history of hypertension, and history of cardiac disease were evaluated as predictors of myocardial infarction and cardiac arrest using stepwise multivariate logistic regression. A series of predictive scores were constructed and weighted to identify the influence of each variable on 30-day postoperative cardiac events, while comparing with the Revised Cardiac Risk Index (RCRI).

RESULTS

Among 85,129 patients, age ≥80 years, hypertension, and a history of cardiac disease were all statistically significant predictors of postoperative cardiac events (0.32%; n = 275) after TKA and THA (P ≤ .02). Equal weighting of all variables maintained the highest discriminative capacity in both THA and TKA cohorts. Adjusted models explained 75% and 71% of the variation in postoperative cardiac events for those with THA and TKA, respectively, without statistically significant lack of fit (P = .52; P = .23, respectively). Conversely, the RCRI was not a significant predictor of postoperative cardiac events after TKA (odds ratio, 3.36; 95% CI, 0.19, 58.04; P = .40), although it maintained a similar discriminative capacity after THA (76%).

CONCLUSION

The current total joint arthroplasty Cardiac Risk Index score was the most economical in predicting postoperative cardiac complication after primary unilateral TKA and THA. The RCRI was not a significant predictor of perioperative cardiac events for TKA patients but performed similarly to the current model for THA.

Cardiac screening with electrocardiography, stress echocardiography, or myocardial perfusion imaging: advice for high-value care from the American College of Physicians

BACKGROUND

Cardiac screening in adults with resting or stress electrocardiography, stress echocardiography, or myocardial perfusion imaging can reveal findings associated with increased risk for coronary heart disease events, but inappropriate cardiac testing of low-risk adults has been identified as an important area of overuse by several professional societies.

METHODS

Narrative review based on published systematic reviews; guidelines; and articles on the yield, benefits, and harms of cardiac screening in low-risk adults.

RESULTS

Cardiac screening has not been shown to improve patient outcomes. It is also associated with potential harms due to false-positive results because they can lead to subsequent, potentially unnecessary tests and procedures. Cardiac screening is likely to be particularly inefficient in adults at low risk for coronary heart disease given the low prevalence and predictive values of testing in this population and the low likelihood that positive findings will affect treatment decisions. In this patient population, clinicians should focus on strategies for mitigating cardiovascular risk by treating modifiable risk factors (such as smoking, diabetes, hypertension, hyperlipidemia, and overweight) and encouraging healthy levels of exercise.

HIGH-VALUE CARE ADVICE

Clinicians should not screen for cardiac disease in asymptomatic, low-risk adults with resting or stress electrocardiography, stress echocardiography, or stress myocardial perfusion imaging.

Relation between Framingham risk categories and the presence of functionally relevant coronary lesions as determined on multislice computed tomography and stress testing

Noninvasive assessment of subclinical atherosclerosis by multislice computed tomographic (MSCT) coronary angiography and demonstration of significant, flow-limiting coronary artery disease (CAD) by stress testing may improve patients' risk stratification. However, data relating the complementary information provided by these noninvasive techniques to traditional risk assessment are scarce. In 255 subjects (45% women, mean age 54 +/- 12 years) without known CAD, 64-slice MSCT coronary angiography and stress testing (exercise electrocardiographic test or myocardial perfusion imaging) were performed. Framingham risk score (FRS) was calculated from baseline characteristics (50% low, 22% intermediate, 28% high). Angiograms showing atherosclerosis were classified as obstructive (> or =50% luminal narrowing) CAD or not. Stress tests were classified as normal or abnormal. Multislice computed tomogram identified 155 patients (61%) with CAD, of whom 78 (31%) showed obstructive CAD. A positive stress test result was observed in 36 patients (46%) with obstructive CAD. In line with increasing FRS categories, a significant increase in the prevalence of functionally relevant obstructive CAD was observed (6% low vs 45% intermediate vs 63% high, p <0.001). In conclusion, a strong positive relation exists between FRS and prevalence of functionally relevant obstructive CAD. Selective use of MSCT coronary angiography and stress testing may refine the traditional risk assessment of CAD events, especially in patients deemed at intermediate and high risk.