Electrocardiographic exercise stress testing: an update beyond the ST segment

Evaluation of the QRS score for diagnosing coronary artery disease in women: A Finnish cardiovascular study

BACKGROUND

Exercise electrocardiography is a widely used diagnostic modality for diagnosing coronary artery disease. This method has been used for both sexes; however, its diagnostic accuracy in women is limited.

METHODS

The study analyzed 332 women participating in the Finnish Cardiovascular Study. Among 332 women, 125 with angiographically proven coronary artery disease (mean age 62.1 ± 9.5 years), 91 with a low likelihood of coronary artery disease (mean age 47.3 ± 13.5 years), and 116 without angiographically proven coronary artery disease (mean age 56.3 ± 9.9 years) were analyzed. The Q, R, S, and ST-segment changes and QRS score were determined by subtracting the Q, R, S, and ST-segment amplitudes immediately after the maximal exercise changes from their rest values (Δ). Receiver operating characteristic curve analysis was performed to evaluate the overall diagnostic performance of the parameters for predicting coronary artery disease.

RESULTS

The areas under the receiver operating characteristic curve between coronary artery disease and low likelihood of coronary artery disease groups for the QRS score and ΔSTV5, ΔQaVF, and ΔRaVF were 0.75, 0.73, 0.71, and 0.71, respectively. These areas were lower (0.62, 0.57, 0.60, and 0.60, respectively) between the groups with and without angiographically proven coronary artery disease. QRS score demonstrated the highest sensitivity at 80% specificity (61.5%) and the highest specificity at 80% sensitivity (57.6%).

CONCLUSIONS

This study suggests that the QRS and ST-segment depression have a moderate diagnostic ability to predict coronary artery disease in women. Q and R waves in lead aVF showed good diagnostic ability.

Comparative Analysis of the Diagnostic Effectiveness of SATRO ECG in the Diagnosis of Ischemia Diagnosed in Myocardial Perfusion Scintigraphy Performed Using the SPECT Method

There is a great need for early diagnosis of ischemic heart disease (IHD), the most common cause of which is haemodynamic disorders caused mainly by obstructive atherosclerosis of the coronary arteries. The diagnosis of IHD is usually made with the use of functional tests, which include resting ECG (R) or examination of significant perfusion disorders during exercise using the SPECT method. Despite the fact that the ECG (R) test is commonly used in cardiological diagnostics, it has a limited diagnostic value, especially in people with a low probability of coronary artery disease (CAD). In order to increase the effectiveness of the ECG (R) examination, SATRO ECG software, based on the single fibres heart activity model (SFHAM), was used to evaluate the electrocardiograms. The introduction of new classifiers from the available medical data to the analysis made it possible to evaluate the diagnostic efficacy of SATRO ECG (TOT) in predicting significant perfusion disorders in the exercise SPECT (TOT 2). These disorders are most often caused by obstructive atherosclerosis of the coronary arteries, which is the main cause of CAD. The database of 316 patients (219 men and 97 women, aged 57 ± 10 years) was analyzed using resting and stress ECG, perfusion scintigraphy performed using the SPECT method, and SATRO ECG analysis. The diagnostic efficacy parameters of SATRO ECG (TOT) in predicting significant perfusion abnormalities in the exercise-induced SPECT (TOT 2) study were: sensitivity, 99%; specificity, 91%; concordance, 96%; and positive, 96%, and negative, 97%, predictive values. The Kappa-Cohen coefficient was 0.92, and the statistical significance coefficient was p < 0.001. These results indicate a statistically significant agreement in the diagnosis of IHD in both diagnostic methods used.

Functionally Complete Coronary Revascularisation in Patients Presenting with ST-elevation MI and Multivessel Coronary Artery Disease

Up to half of patients undergoing primary percutaneous coronary intervention of a culprit stenosis in the context of the ST-elevation MI may present with multivessel disease. The presence of non-culprit stenoses have been shown to affect the outcomes of these patients, and the results of the more recent randomised trials highlight the importance of complete coronary revascularisation. In this paper, the authors review the main trials published on the topic and discuss tools for the assessment of non-culprit stenoses, while considering the right time for carrying out a complete coronary revascularisation.

Exercise-Induced Premature Ventricular Contractions Are Associated With Myocardial Ischemia Among Asymptomatic Adult Male Firefighters: Implications for Enhanced Risk Stratification

BACKGROUND

Exercise-induced premature ventricular contractions (EI-PVCs) are associated with an increased risk of cardiovascular disease among asymptomatic adult males, but the underlying mechanisms remain understudied. Myocardial ischemia due to cardiovascular disease reduces coronary blood flow, may impair exercise performance, and initiates EI-PVCs; thus, EI-PVCs may be an early indicator of cardiovascular disease.

OBJECTIVE

The objective of this study was to determine whether EI-PVCs are associated with myocardial ischemia and reduced exercise performance among asymptomatic adult firefighters.

METHODS

Asymptomatic adult firefighters free of known cardiovascular disease underwent exercise treadmill testing. A 12-lead electrocardiography was placed on participants for 24 hr afterward to measure EI-PVCs in recovery. Univariate and multivariate binary logistic regression models were used to assess the odds of myocardial ischemia. Sensitivity and specificity analyses were conducted. Statistical significance was set at p < .05.

RESULTS

Participants comprised 86 asymptomatic adult males. The prevalence of myocardial ischemia was 30.8%. A single EI-PVC was associated with myocardial ischemia (χ² = 8.98; p = .003). EI-PVC remained a significant predictor despite adjustment for other cardiovascular risks (odds ratio = 4.281, p = .038). Although not statistically significant, the EI-PVC group achieved lower total exercise time (11.4 ± 2.9 vs. 12.4 ± 3.0 min, p = .13), lower metabolic equivalent of tasks (METs; 11.6 ± 2.6 vs. 12.8 ± 2.3 METs, p = .06), and a lower maximum exercise speed (4.4 ± 0.7 vs. 4.7 ± 0.8 miles/hr, p = .07).

DISCUSSION

EI-PVCs are associated with myocardial ischemia among asymptomatic male firefighters, providing additional evidence of the association between EI-PVCs and myocardial ischemia and suggesting EI-PVCs as an early indicator of cardiovascular disease.

The relationship between erectile dysfunction and the Atherogenic Index of Plasma

The objective of this study was to compare the Atherogenic Index of Plasma (AIP) values as indicators of subclinical atherosclerosis among 124 patients with erectile dysfunction, which was thought to be vasculogenic and 126 control subjects who had no erectile dysfunction, and to compare cardiac performance values between both the groups using exercise stress tests (EST). Erectile function was assessed using the International Index of Erectile Function (IIEF-5) questionnaire form. AIP values were studied and compared between patients with ED (IIEF  <  22) and those without ED (IIEF  >  22) using the log₁₀ TG/HDL-C formula. In addition, the correlation between the severity of ED and AIP was investigated according to IIEF-5 scoring. Metabolic equivalent (MET) values, maximal heart rates (max HR), and heart rate recovery (HRR) were evaluated with effort tests. AIP values were significantly higher in the ED group than in the control group (0.45  ±  0.27, and 0.37  ±  0.27; p  =  0.015). According to IIEF-5 scoring, AIP values increased as ED scores decreased. In the EST, MET score and max HR values were significantly lower in the ED group (METs: 11.1  ±  2.2, and 11.6  ±  2.2; p  =  0.045; Max HR: 162.8  ±  6.1, and 165  ±  8.7; p  =  0.019). Although not statistically significant, HRR values were lower in the ED group. Higher AIP values were found in the ED group, and a positive correlation was established between AIP and the severity of ED. In addition, lower performance during the EST and lower HRR values, again in the ED group, confirms cardiac interaction with ED. These results indicate the importance of referral of patients with ED from urology clinics to cardiology units for risk determination and cardiac assessment, even if they areasymptomatic.

Prognostic Performance of Heart Rate Recovery on an Exercise Test in a Primary Prevention Population

BACKGROUND

Heart rate (HR) recovery has been investigated in specific patient cohorts, but there is less information about the role of HR recovery in general populations. We investigated whether HR recovery has long-term prognostic significance in primary prevention.

METHODS AND RESULTS

Exercise tests performed between 1993 and 2010 on patients aged 30 to 79 years without cardiovascular disease were included. Mortality was determined from Mayo Clinic records and Minnesota Death Index. Total, cardiovascular, and non-cardiovascular mortality was reported according to HR recovery <13 bpm using Cox regression. 19 551 patients were included, 6756 women (35%), age 51±10 years. There were 1271 deaths over follow-up of 12±5 years. HR recovery declined after age 60, and was also lower according to diabetes mellitus, hypertension, obesity, current smoking, and poor cardiorespiratory fitness but not sex or β-blockers. Adjusting for these factors, abnormal HR recovery was a significant predictor of total (hazard ratio [95% confidence interval]=1.56 [1.384-1.77]), cardiovascular (1.95 [1.57-2.42]), and non-cardiovascular death (1.41 [1.22-1.64]). Hazard ratios for cardiovascular death according to abnormal HR recovery were significant in all age groups (30-59, 60-69, 70-79), in both sexes, in patients with and without hypertension, obesity, and diabetes mellitus, but not in patients taking β-blockers, current smokers, and patients with normal cardiorespiratory fitness.

CONCLUSIONS

HR recovery is a powerful prognostic factor predicting total, cardiovascular, and non-cardiovascular death in a primary prevention cohort. It performs consistently well according to sex, age, obesity, hypertension, and diabetes mellitus but shows diminished utility in patients taking β-blockers, current smokers, and patients with normal cardiorespiratory fitness.

Utility of Imaging in Risk Stratification of Chest Pain in Women

OPINION STATEMENT

Recent decades have seen a growing recognition that the understanding of sex differences in cardiovascular disease (CVD) is vital to optimal diagnosis and management, particularly of women (Mosca et al. Circulation 124:2145-54, 2011). There is simultaneously an increasing appreciation of the multifactorial nature of ischemic heart disease (IHD) in many patients, in whom disease may extend beyond the epicardial coronaries. While obstructive coronary artery disease (CAD) remains underdiagnosed in women and still represents a major burden of disease, women also present with nonobstructive CAD more commonly than men (Patel et al. N Engl J Med 362:886-95, 2010). Indeed, microvascular dysfunction, coronary artery vasospasm, and coronary dissections contribute to a larger proportion of IHD in women than men (Bairey Merz et al. J Am Coll Cardiol 47:S21-9, 2006). Here, we review the symptom presentation of women with IHD and the noninvasive modalities used to risk stratify women with suspected IHD.

High-frequency QRS analysis superior to conventional ST-segment analysis of women with chest pain

BACKGROUND

The novel analysis of high-frequency QRS components (HF/QRS) has been proposed in patients with chest pain (CP) referred for exercise tolerance test (ex-ECG). We sought to evaluate the prognostic role of exercise high-frequency QRS-analysis (ex-HF/QRS) in patients with recent-onset stable CP, in the emergency setting.

METHODS

Patients with CP underwent ex-ECG. A decrease greater than or equal to 50% of the signal of HF/QRS intensity was considered as index of ischemia as ST-segment depression greater than or equal to 2 mm or greater than or equal to 1 mm associated with CP. Exclusion criteria were QRS duration greater than or equal to 120 milliseconds and inability to exercise. Baseline characteristics were adjusted with the propensity score matching specifying nearest-neighbor matching in cardiovascular risk factors and risk scores. The primary end point was the composite of coronary stenosis greater than or equal to 70% or acute coronary syndrome, revascularization, and cardiac death on the 6-month follow-up.

RESULTS

Of 589 patients, 22 achieved the end point. On the univariate analysis, known cardiovascular disease, GRACE score, and ex-HF/QRS were predictors of the end point. On the multivariate analysis, only ex-HF/QRS was predictor of the end point (odd ratio, 28; 95% confidence interval [CI], 6-120; P < .001). Overall, the ex-HF/QRS when compared to ex-ECG showed higher sensitivity (91% vs 27%; P = .02), lower specificity (74% vs 86%; P = .09), and comparable negative predictive value (99% vs 97%; P = .78). Receiver operating characteristic curve analysis showed the larger area of ex-HF/QRS (0.83; 95% CI, 0.75-0.90) over ex-ECG (0.57; CI, 0.44-0.70) and GRACE score (0.65; CI, 0.54-0.76); P < .03 on C-statistic. Women showed the largest area (0.89; CI, 0.83-0.95; P < .03) vs the other clinical data.

CONCLUSIONS

In patients with CP, the novel ex-HF/QRS analysis has a valuable incremental prognostic role over ex-ECG, especially in women.

Comparison of exercise electrocardiogram and exercise echocardiography in intermediate-risk chest pain patients

BACKGROUND

The novel exercise computer-assisted high-frequency QRS analysis (HF/QRS) has demonstrated improved sensitivity and specificity over the conventional ST/electrocardiogram-segment analysis (ST/ECG) in the detection of myocardial ischemia. The aim of the present study was to compare the diagnostic value of the validated exercise echocardiography (ex-Echo) with the novel exercise ECG (ex-ECG) including HF/QRS and ST/ECG analysis.

METHODS

A prospective cohort study was conducted in the emergency department of a tertiary care teaching Hospital. Patients with chest pain (CP), normal resting ECGs, troponins, and echocardiography, labeled as "intermediate-risk" for adverse coronary events, underwent the novel ex-ECG and ex-Echo. An ST-segment depression of at least 2 mV or at least 1 mV when associated with CP was considered as an index of ischemia, as well as a decrease of at least 50% in HF/QRS intensity, or new wall motion abnormalities on ex-Echo. Exclusion criteria were QRS duration of at least 120 milliseconds, poor echo-acoustic window, and inability to exercise. Patients were followed up to 3 months. The end point was the composite of coronary stenoses of 50% or greater at angiography or acute coronary syndrome, revascularization, and cardiovascular death on the 3-month follow-up.

RESULTS

Of 188 patients enrolled, 18 achieved the end point. The novel ex-ECG and ex-Echo showed comparable negative predictive value (97% vs 96%; P = .930); however, sensitivity was 83% vs 61%, respectively (P = .612), and specificity was 64% vs 92%, respectively,(P = .026). The areas on receiver operating characteristic analysis were comparable (ex-ECG: 0.734 [95% confidence interval, or CI, 0.62-0.85] vs ex-Echo: 0.767 [CI, 0.63-0.91]; C statistic, P = .167). On multivariate analysis, both ex-ECG (hazard ratio, 5; CI, 1-20; P = .017) and ex-Echo (HR, 12; CI, 4-40; P < .001) were predictors of the end point.

CONCLUSIONS

In intermediate-risk CP patients, the novel ex-ECG including HF/QRS added to ST/ECG analysis was a valuable diagnostic tool and might be proposed to avoid additional imaging. However, the novel test needs additional study before it can be recommended as a replacement for current techniques.

Improved detection of ischemic heart disease by combining high-frequency electrocardiogram analysis with exercise stress echocardiography

Background and Objectives

Because the exercise treadmill test (ETT) based on ST-segment analysis is limited due to low sensitivity and specificity, there has been an interest in the additional analysis of high-frequency components of QRS (HFQRS) for the detection of coronary artery disease (CAD). We sought to evaluate the feasibility and clinical usefulness of HFQRS analysis during exercise stress echocardiography (ESE).

Subjects and Methods

We evaluated 175 patients (age 57±9,118 men) who performed ESE and either coronary computed tomographic angiography or coronary angiography. ETT was performed using the HyperQ stress system for both conventional ST-segment analysis and HFQRS intensity analysis.

Results

Thirty-two patients (31%) had significant CAD. The sensitivity and specificity of HFQRS analysis were 68.8% and 74.8%, respectively. The combined model, including HFQRS analysis and ESE, provided the best diagnostic accuracy, with the area under the receiver-operating characteristics curve (AUC) of 0.948 {95% confidence interval (CI)=0.913-0.984} compared with ST-segment analysis (AUC 0.679, 95% CI=0.592-0.766).

Conclusion

HFQRS analysis during ESE is feasible and may provide additional diagnostic information for the detection of significant CAD.

An update on exercise stress testing

Exercise stress testing is the most commonly used noninvasive method to evaluate for coronary artery disease in men and women. Although emphasis has been placed on the diagnostic value of ST-segment depression, the exercise stress test provides other valuable diagnostic and prognostic data, beyond ST-segment depression. The value of these variables, which include exercise capacity, chronotropic response, heart rate recovery, blood pressure response, and the Duke Treadmill Score, are reviewed in this article. In addition, the gender differences seen with these exercise testing variables are reviewed. In this modern era of exercise stress testing, making use of all the information from a stress test and creating a comprehensive stress testing report are recommended in the evaluation of patients with suspected coronary artery disease who undergo exercise stress testing.

Use of electrocardiographic depolarization abnormalities for detection of stress-induced ischemia as defined by myocardial perfusion imaging

High-frequency mid-QRS (HFQRS) analysis was recently introduced as a tool for identification of stress-induced ischemia. The diagnostic performance of this electrocardiographic technique has not been determined in a large cohort of patients. This study compared the diagnostic performance of HFQRS analysis to conventional ST-segment analysis in detecting exercise-induced ischemia. The study included 996 patients (56 ± 10 years of age, 670 men) referred for exercise myocardial perfusion imaging (MPI), which served as the gold standard of ischemia. High-resolution electrocardiogram was used for computer analysis of HFQRS signals. Number of electrocardiographic leads with ≥50% decrease of HFQRS intensity (L(50%)) was used as an index of ischemia. Perfusion images were evaluated semiquantitatively. Receiver operating characteristic analysis demonstrated an L(50%) ≥3 as the criterion that yielded optimal sensitivity and specificity for diagnosing moderate/severe ischemia. Compared to ST-segment analysis HFQRS analysis was more sensitive (69% vs 39%, p <0.005) and more specific (86% vs 82%, p <0.05). L(50%) correlated with amount of MPI ischemia (R(2) = 0.75, p <0.0001). Multivariate logistic regression analysis demonstrated a significant incremental diagnostic value for the addition of HFQRS data to a model containing pretest and conventional exercise parameters. L(50%) was the best predictor of mild or moderate/severe MPI ischemia. In conclusion, computerized HFQRS analysis improved the diagnostic performance of conventional stress electrocardiogram in detecting exercise-induced ischemia. Thus, this technique might aid in the noninvasive evaluation of coronary artery disease.

Exercise-induced ST-segment depression in inferior leads during treadmill exercise testing and coronary artery disease

The exercise electrocardiogram is a commonly used non-invasive and inexpensive method for detection of electrocardiogram (ECG) changes secondary to myocardial ischemia. Reversible ST-segment depression is the characteristic finding associated with exercise-induced, demand-driven ischemia in patients with significant coronary obstruction but no flow limitation at rest. The exercise-induced ST-segment depression in inferior leads has been questioned and it has been reported that lead V5 alone consistently outperforms the inferior leads and the combination of lead V5 with II, because lead II has a high false-positive rate. A review of the 12-lead visual electrocardiographic interpretations confirmed that changes isolated to the inferior leads were rare in patients, who had no diagnostic Q waves. Considering the sum of ST-segment depression or the most depression in the three leads representing the three main areas of the myocardium (II, V2, and V5) did not improve the diagnostic capacity of the test. A case is presented to illustrate how in a patient, the ST-segment depression in inferior leads during exercise testing is related with significant coronary artery disease. We present a case of exercise-induced ST-segment depression in inferior leads in a 52 year-old Italian man. This experience demonstrates that ST-segment depression in inferior leads during the exercise testing can have a diagnostic significance.

Quantifying exertion level during exercise stress testing using percentage of age-predicted maximal heart rate, rate pressure product, and perceived exertion

OBJECTIVE

To determine if the attainment of at least 85% of age-predicted maximal heart rate (APMHR), using the equation 220 - age, and/or at least 25,000 as the product of maximal heart rate and systolic blood pressure (rate pressure product, RPP) is an accurate indicator of exertion level during exercise stress testing.

PATIENTS AND METHODS

From May 1, 2009, to February 15, 2010, 238 patients (mean ± SD age, 49.3±11.9 years; 50% male) with symptoms suggestive of myocardial ischemia underwent an exercise stress test with the addition of ventilatory expired gas analysis and a myocardial perfusion study. Ventilatory expired gas analysis determined the peak respiratory exchange ratio (RER), which is considered a valid and reliable variable for quantifying a patient's exertion during exercise.

RESULTS

Of the patients, 207 (87%) attained a peak RER of 1.00 or more, and 123 (52%) attained a peak RER of 1.10 or more. An APMHR of 85% or more and peak RPP of 25,000 or more were both ineffective in identifying patients who put forth a maximal exercise effort (ie, peak RER, ≥1.10). Perceived exertion was a significant indicator (P=.04) of patient exertion, with a threshold of 15 (6-20 scale) being an optimal cut point. The percentage of equivocal myocardial perfusion study results was significantly higher in patients who demonstrated a submaximal exercise effort by peak RER (P≤.007).

CONCLUSION

Aerobic exercise testing is an integral component in the assessment of patients with suspected myocardial ischemia. Our findings indicate that the currently used percentage of APMHR and peak RPP thresholds are ineffective in quantifying a patient's level of exertion during exercise stress testing.

Coronary artery disease is common in asymptomatic patients with signs of myocardial ischemia

BACKGROUND

The incidence of coronary artery disease (CAD) in totally asymptomatic patients with myocardial ischemia during stress testing is unknown.

METHODS

54 patients with asymptomatic myocardial ischemia participated in the Swiss Interventional Study on Silent Ischemia type I (SWISSI I). Asymptomatic myocardial ischemia was verified by bicycle ergometry and stress imaging (echocardiography or scintigraphy). Findings from coronary angiographies in the course of the study constituted the main outcome.

RESULTS

Of the 54 study participants, 29 patients (53.7%) underwent coronary angiography. CAD was found in 27 of 29 patients (93.1%). In those 27 patients with CAD, 9 patients (33.3%) suffered from single vessel disease, 9 patients (33.3%) from two vessel disease, and 9 patients (33.3%) from triple vessel disease. Two patients showed left main coronary artery stenosis.

CONCLUSION

This study shows a high incidence of relevant CAD among totally asymptomatic patients with myocardial ischemia during stress testing. Previously healthy subjects with exercise-induced ST-segment depression at check-up examinations, even if asymptomatic, should have further diagnostic evaluation.

Normal resting electrocardiographic variants in young athletes

With a growing awareness of the tragedy of sudden cardiac arrest (SCA) in young athletes, more extensive pre-participation examinations are being performed prior to competitive sport participation. In addition to a history and physical, young athletes often have a 12-lead resting electrocardiogram (ECG) to better identify heart disease associated with SCA. Complicating this process is that certain "abnormal" resting ECG findings are considered normal variants in healthy children and young adults. The ability to recognize these normal variants is often useful in preventing excessive referral of patients to cardiologists for evaluation of resting ECG's that are benign variations of normal and in making sound decisions regarding appropriate clearance to exercise. This review describes these normal variants.

KEYWORDS

normal variants; early repolarization; athlete's heart.