Version May 2024
INTRODUCTION — Stress testing in patients with known or suspected coronary heart disease (CHD) provides information about prognosis as well as diagnosis. This topic will provide an overview of the utility of stress testing for estimation of prognosis as a guide to management in patients with known or suspected CHD. The methodology, indications, and contraindications of stress testing are discussed separately.
●(See "Exercise ECG testing: Performing the test and interpreting the ECG results".)
●(See "Stress testing for the diagnosis of obstructive coronary heart disease".)
●(See "Risk stratification after non-ST elevation acute coronary syndrome", section on 'Stress testing'.)
●(See "Risk stratification after acute ST-elevation myocardial infarction", section on 'Stress testing'.)
INDICATIONS FOR STRESS TESTING FOR PROGNOSIS — All indications for performing a stress test for the diagnosis of CHD are also indications for performing a stress test for risk stratification and prognosis. Common indications for performing a stress test include:
●Symptoms suggestive of myocardial ischemia
●Acute chest pain after acute coronary syndrome (ACS) has been excluded
●Recent ACS with no or incomplete revascularization
●Worsening symptoms with known CHD
●Preoperative evaluation for high-risk noncardiac surgery
The indications for stress testing are discussed in detail separately. (See "Selecting the optimal cardiac stress test", section on 'Indications for stress testing'.)
EXERCISE ECG — Exercise stress testing provides more information about prognosis than pharmacologic stress testing. Exercise capacity is one of the strongest determinants of prognosis, and predicts mortality and cardiovascular events, particularly in older adults [1-4]. The heart rate and blood pressure responses to exercise stress also provide prognostic information. Finally, evidence of the presence and extent of stress-induced myocardial ischemia also provides important prognostic information. Among patients who undergo exercise stress, a number of variables, either alone or in combination, are associated with an increased risk of an adverse outcome in patients with CHD [2,5-12]. These include:
●Poor exercise capacity
●Exercise-induced angina, particularly that which is exercise-limiting or occurs at a low workload
●Low peak systolic blood pressure (<130 mmHg) or a fall in systolic blood pressure below baseline during exercise [12]
●Low peak heart rate (ie, chronotropic incompetence) (see 'Heart rate response to exercise' below)
●Slow recovery of heart rate after exercise
There are also a number of ECG findings during exercise that indicate inducible myocardial ischemia and convey a worse prognosis:
●ECG evidence of inducible ischemia (≥1 mm of downsloping or flat ST segment depression during exercise or recovery)
●≥2 mm of ischemic ST depression at a low workload (stage 2 or less or ≤130 beats per minute)
●Early onset (stage 1) or prolonged duration (>5 minutes) of ST depression
●Multiple leads (>5) with ST depression
●ST segment elevation (in leads without pathologic Q waves and not in aVR)
●Ventricular couplets or tachycardia at a low workload or during recovery
The prognosis after exercise ECG testing may be better predicted with the use of treadmill scores that take into account multiple variables. (See 'Duke treadmill score' below.)
Exercise capacity — Patients with poor exercise capacity are at increased cardiovascular risk, while those with excellent exercise capacity (a measure of fitness) are at reduced risk [13]. The importance of exercise capacity was illustrated in a report of 6213 consecutive men referred for exercise testing who were then followed for a mean of 6.2 years [2]. After adjustment for age, peak exercise capacity, measured in metabolic equivalents (METs), was the strongest predictor of mortality among men, whether or not they had cardiovascular disease. One MET is defined as the resting oxygen uptake in a sitting position (3.5 mL O2 uptake/kg per minute), and can be estimated from any of the commonly used exercise protocols. For each 1 MET increase in exercise capacity, there was a 12 percent improvement in survival. The achieved exercise capacity and workload have also been shown to be predictive in older adult populations [3,4].
Flat or downsloping ST depression — A positive exercise ECG test is defined as ≥1 mm horizontal (flat) or a downsloping ST segment depression measured at 80 milliseconds after the end of the QRS complex, as recommended by the ACC/AHA guidelines [14]. In addition to providing diagnostic information [15], ST segment depression provides prognostic information, especially when considered in the context of the level of exercise that leads to ST depression. (See "Exercise ECG testing: Performing the test and interpreting the ECG results", section on 'ST segment depression'.)
Flat or downsloping ST depression can occur during exercise and during recovery and has prognostic significance at both time periods.
●In one study of 1472 patients who underwent exercise stress testing and coronary angiography, patients who developed ≥1 mm ST depression in stage 1 or 2 of the Bruce protocol (table 1) or at heart rates less than 120 beats per minute had a poor prognosis (12-month survival of less than 85 percent) and a high probability of significant left main (25 percent) or three vessel disease (more than 60 percent) [7]. In contrast, the ability to exercise into stage 4 (>10 METs) or to achieve a maximal heart rate greater than 160 beats per minute with <1 mm ST depression was associated with an excellent prognosis (12-month survival more than 99 percent).
●Among 4083 medically-treated patients with stable angina enrolled in the Coronary Artery Surgery Study (CASS) Registry, patients with ≥1 mm exercise-induced ST depression and final stage ≤1 of the Bruce protocol (table 1) were at high risk with an average annual mortality rate of approximately 5 percent per year [5]. In contrast, patients who had <1 mm ST depression and final exercise stage ≥3 on the Bruce protocol were at low risk with an annual mortality of less than 1 percent per year.
Heart rate response to exercise — An impaired heart rate response to exercise, known as chronotropic incompetence, is generally defined as failure to achieve 85 percent of the age-predicted maximum heart rate in the absence of medications known to blunt the heart rate response to exercise (eg, beta blockers or non-dihydropyridine calcium channel blockers). While there are some conflicting data, chronotropic incompetence is generally thought to be predictive of all-cause mortality and CHD risk [11,16-18].
●In a prospective cohort of 2953 patients, 11 percent failed to achieve at least 85 percent of the age-predicted maximal heart rate [17] and had a significant increase in mortality at two years (absolute increase 4 percent, adjusted relative risk [RR] 1.84) (figure 1).
●Similar findings were noted in a report of 3221 patients undergoing treadmill exercise echocardiography in which 495 patients (15 percent) failed to achieve at least 85 percent of the age-predicted maximal heart rate [18]. At a median follow-up of 3.2 years, these patients had significant increases in all-cause and cardiac mortality compared with patients with >85 percent of age-predicted maximal heart rate (adjusted risk 1.5 and 2.1).
Heart rate recovery after exercise — Delayed return of the heart rate to the normal range after exercise, probably a reflection of decreased vagal reactivation, provides important prognostic information among patients with known CAD as well as among all patients referred for exercise testing. The definitions of abnormal heart rate recovery (HRR) have varied in different studies from ≤12 to ≤18 beats per minute at one minute [19-22] to ≤22 to ≤42 beats per minute at two minutes [23-25]. Late HRR (five minutes after the cessation of exercise) has also been defined and investigated [26].
●In a study of 2428 patients referred for exercise stress testing, abnormal HRR (defined as ≤12 beats per minute) while the patient was exercising lightly during the one minute "cool-down phase" was associated with an increase in overall mortality at six-year follow-up (figure 2) [19]. In a follow-up study of 9454 subjects at the same institution, mortality at five years was independently predicted by both abnormal HRR and an intermediate or high Duke treadmill score (8 versus 2 percent in those with a low score) [20]. The predictive value of abnormal HRR was independent of the angiographic severity of coronary disease [21]. (See 'Duke treadmill score' below.)
●In a systematic review which included four studies and 2428 patients with documented pre-existing CAD referred for exercise stress testing, abnormal HRR (defined variably as ≤12 to 21 beats per minute) was associated with greater than fivefold risk of mortality [27].
●In patients who undergo exercise echocardiography requiring them to lie down immediately (rather than having a cool down phase) after exercise cessation, abnormal HRR (≤18 beats per minute) independently predicts increased mortality [22].
●Late HRR at five minutes post-exercise appears to provide additional prognostic information beyond that acquired with abnormal HRR at one minute. In a cohort of 2082 patients who underwent exercise testing and were followed for an average of 10 years, patients with impaired late HRR at five minutes had significantly higher all-cause mortality [26].
Exertional hypotension — Exertional hypotension, defined as a fall in systolic blood pressure below that measured standing at rest, is fairly rare during exercise testing but when present suggests a poor prognosis, likely due to underlying heart failure or severe multivessel coronary disease [12]. In patients with exercise-induced ischemia or prior myocardial infarction (MI), exertional hypotension is associated with an increased risk for new cardiac events. Other causes of exercise-induced hypotension include fixed cardiac output (as seen with stenotic valvular heart disease or hypertrophic cardiomyopathy), volume depletion, anemia, or certain drugs (such as vasodilators). The exercise test should stop when exertional hypotension is detected.
Ventricular arrhythmias
Premature ventricular complexes — Exercise-induced ventricular ectopy occurs in 2 to 8 percent of asymptomatic men and women and in 7 to 20 percent of patients undergoing exercise ECG testing for known or suspected coronary disease. Exercise-induced premature ventricular complexes (PVCs) are more common in people with increasing age, male sex, a history of hypertension, and a history of obesity, but are not more frequent in patients with ischemic ST-segment changes [28,29].
Exercise-induced PVCs appear to be associated with a worse long-term prognosis. In a meta-analysis of nine studies of over 62,000 people, those with PVCs on stress testing had increased risks for all-cause mortality (RR 1.41, 95% CI 1.23-1.61) and cardiovascular mortality (RR 1.86, 95%CI 1.51-2.30) [30].
There are a number of caveats regarding the association of PVCs with cardiovascular mortality:
●Occurrence during exercise versus recovery phase – High-grade PVCs (>10 per minute, couplets, multifocal, R-on-T type, or nonsustained ventricular tachycardia [NSVT]) appear to confer long-term risk of cardiovascular mortality when they occur during the recovery phase but not if they occur only during exercise [31,32].
In an analysis of two studies with relevant data, PVCs during recovery were associated with an increased risk of mortality (RR 1.55, 95% CI 1.22-1.96), and PVCs during exercise were associated with a nonsignificant trend towards greater risk of mortality (RR 1.14, 95% CI 0.96-1.34) [30]. Studies performed in asymptomatic patients have shown similar results [32].
●Frequency during exercise – In observational studies, people with frequent exercise-induced PVCs (eg, defined as ≥2 sequential PVCs, 10 percent during a 30-second recording, multifocal PVCs) have been at higher risk for cardiovascular mortality over the subsequent two decades, with excess adjusted risks ranging from a hazards ratio (HRs) of 1.53 to an RR of 2.5 [33,34]. (figure 3).
Exercise-induced PVCs are related in similar magnitude to all-cause mortality, even when the PVCs occur in relatively low amounts [28].
●Known or suspected coronary heart disease – In patients with known or suspected coronary disease, ventricular ectopy on exercise treadmill stress testing has been associated with higher mortality [35-37]; however, these PVCs were not shown independently to add prognostic information over and beyond the coronary angiogram [36].
It remains uncertain whether PVCs during exercise are an independent risk factor or a marker for more severe underlying disease; PCVs may originate from areas of myocardial fibrosis or scarring. The role of myocardial fibrosis was supported by data from 36 athletes referred for cardiac magnetic resonance imaging (CMR) to investigate frequent PVCs. Participants with exercise-induced PVCs were more likely to have cardiac fibrosis on CMR than those with non-exercise-induced PVCs (47 versus 13 percent) [38]. The majority of scarring was in a nonischemic pattern.
Nonsustained ventricular tachycardia — The occurrence of NSVT during exercise in patients without apparent heart disease does not affect long-term prognosis [39-41]. However, the presence of NSVT or high-grade PVCs in the recovery phase has been associated with increased risk of cardiovascular mortality [32,33]. The mechanism underlying the increased risk is unclear.
NSVT was noted in 3.7 percent of 2099 asymptomatic adult volunteers who underwent stress testing in the Baltimore Longitudinal Study of Aging [42]. After multivariable adjustment for age, sex, and coronary risk factors, people with exercise-induced NSVT had no increased risk of mortality over 13.5 years of follow-up (HR 1.30, 95% CI 0.89-1.90). Findings were similar in a separate cohort of over 1300 asymptomatic airmen undergoing occupational exercise stress testing [43]. In this study, exercise-induced NSVT was not associated with an increased incidence of angina pectoris, myocardial infarction, or sudden death over the following six years.
Atrial arrhythmias — Atrial arrhythmias also occur during exercise [44,45]. In a report of 5375 patients with known or suspected CHD, premature atrial complexes (also referred to a premature atrial beat, premature supraventricular complex, or premature supraventricular beat) occurred in 24 percent, supraventricular tachycardia in 3.4 percent, and atrial fibrillation/flutter in 0.8 percent [44]. In contrast to exercise-induced ventricular arrhythmias, the development of atrial arrhythmias during exercise was not predictive of long-term rates of cardiac death or revascularization after adjustment for clinical and exercise variables.
Exercise-induced LBBB — The development of transient left bundle branch block (LBBB) during exercise testing may also be a marker of increased risk. In a review of 17,277 exercise tests, transient LBBB was noted in 70 (0.4 percent) [46]. The development of LBBB was an independent predictor of death and major cardiac events at four years (adjusted relative risk 2.78).
PROGNOSTIC SCORES
Duke treadmill score — A validated treadmill score from Duke University is based upon data from 2758 consecutive patients seen from 1969 through 1980 with a median age of 49 who had chest pain and underwent both exercise treadmill testing and coronary angiography [8].
The Duke treadmill score (DTS) is calculated from three exercise parameters, where:
●Exercise time is based on minutes completed on Bruce protocol (or equivalent to Bruce protocol)
●ST deviation is the maximum deviation (in mm) compared with baseline
●Angina score: 0 for no pain, 1 for nonlimiting pain, 2 for exercise limiting pain
DTS = Exercise time (minutes) - (5 x ST deviation) - (4 x angina score)
Patients are classified as low, moderate, or high risk according to the score:
●Low risk – score ≥+5
●Moderate risk – score from -10 to +4
●High risk – score ≤-11
Subsequent reports have confirmed the utility of the Duke treadmill score in different groups [47-51]. As an example, the following findings were noted in the different risk groups in an analysis of the original Duke cohort of 2758 medically treated patients [48]:
●Among the 36 percent of patients categorized as low risk, 60 percent had no coronary stenosis ≥75 percent, 16 percent had single vessel disease, and 9 percent had three vessel or left main disease; five-year survival was above 97 percent.
●Among the 9 percent of patients categorized as high risk, 74 percent had three vessel or left main disease, and five-year survival was 65 percent.
●Among the 55 percent of patients categorized as moderate risk, the frequency of three vessel or left main disease (31 percent) and five-year survival (90 percent) were intermediate between the other two groups.
Within each risk class, the prognosis was better in women than men [49]. The Duke treadmill score also appears to perform better in women than men for excluding disease. In a study which included 976 women and 2249 men with chest pain and suspected CHD, fewer low-risk women had any coronary artery with ≥75 percent stenosis (19 versus 47 percent in men) or three vessel or left main disease (3.5 versus 11.4 percent) [49].
The Duke treadmill score added independent prognostic information to that provided by clinical data, coronary anatomy, and LV function. As an example, subset analysis in the original study revealed that among patients with three-vessel disease, those with an abnormal exercise score had a five-year survival rate of 67 percent compared with 93 percent for those with a normal exercise score [8].
Other risk scores — Other treadmill scores have also been devised. One model used exercise testing data from 4083 patients from the Coronary Artery Surgery Study (CASS) registry who were treated medically and followed prospectively [5,52,53]. The presence of significant (≥1 mm) exercise-induced ST depression, the stage of exercise completed, and the extent of LV dysfunction were important determinants of one-year mortality and of the likelihood of three-vessel or left main disease. (See 'Flat or downsloping ST depression' above.)
The Cleveland Clinic nomogram-illustrated model was developed from the results of ECG exercise testing in 30,000 patients referred for suspected coronary heart disease, all of whom had normal baseline ECGs [53]. It was validated in a separate group of over 5000 patients. The Cleveland Clinic model was better able to predict all-cause mortality over three years than the Duke score. However, the Cleveland Clinic model is more difficult to use due to the inclusion of multiple clinical variables such as age, sex, and presence of risk factors, as well as more exercise variables.
RADIONUCLIDE MYOCARDIAL PERFUSION IMAGING — Combined myocardial perfusion and function results from stress radionuclide myocardial perfusion imaging (rMPI) can distinguish patients at high risk (more than 5 percent annual mortality rate) from those at intermediate risk (1 to 5 percent annual mortality rate) or low risk (less than 1 percent annual mortality rate) [54].
The prognostic usefulness of pharmacologic stress rMPI is comparable to that of exercise stress rMPI [1,55]. In a meta-analysis that combined data from 14,918 patients in 24 different studies, exercise stress rMPI and pharmacologic stress rMPI were comparable in their ability to risk-stratify patients [1]. The following discussion will include studies of rMPI that involved both exercise stress testing and pharmacologic stress agents.
Normal rMPI — A normal rMPI has been reported in multiple studies to be associated with low risk of future cardiac events (less than 1 percent per year) [56-64]. As one example of the predictive value of a normal rMPI result, among 5183 consecutive patients with known or suspected CHD who underwent stress rMPI and were followed for an average of 1.8 years, patients with a normal scan (57 percent of patients) had a low risk for cardiac death or MI (≤0.5 and ≤0.3 percent per year, respectively) (figure 4) [56].
The relatively benign prognosis of a normal rMPI scan persists even in patients with a significantly abnormal exercise ECG test or angiographically significant coronary artery disease [57-59,61,65]. In a study of 4649 patients with known or suspected CHD who had an intermediate risk Duke treadmill score (-10 to 4) and a normal or near-normal rMPI, the seven-year survival from cardiovascular death was 99 percent and the seven-year survival from cardiovascular death or MI was 97 percent [59]. (See 'Duke treadmill score' above.)
Patients with known CHD, a high-risk Duke treadmill score, diabetes, chronic kidney disease, and older age have poor outcomes despite a normal scan. The magnitude of these relationships was illustrated in a review of 7376 consecutive patients with a normal exercise or adenosine rMPI [66]. An 80-year-old man with diabetes and known CHD had a relatively high rate of cardiac death or MI at two years (4.9 percent), while a 50-year-old woman without diabetes or known CHD was at minimal risk (0.1 percent).
Abnormal rMPI — High-risk features on rMPI predicting an increased risk of cardiac events include [54,56,57,67-70]:
●Extensive ischemia
●Ischemia in more than one coronary artery territory
●Ischemia in multiple segments
●LVEF <45 percent
●Large fixed defects
●Transient or persistent LV cavity dilatation [71,72]
As one example of the predictive value of an abnormal rMPI result, among 5183 consecutive patients with known or suspected CHD who underwent stress rMPI and were followed for an average of 1.8 years, patients with normal, mildly abnormal, moderately abnormal, or severely abnormal perfusion defects had progressively higher annual cardiac death rates (0.5, 2.7, 2.9, and 4.2 percent, respectively) (figure 4) [56]. Similar findings have subsequently been reported for stress rMPI using regadenoson as the vasodilator [73].
The risk of an abnormal rMPI varies along with the presence or absence of clinical factors [60,74-76]. In a study that incorporated clinical risk factors (older age, diabetes, resting heart rate, dyspnea as a presenting symptom) and findings on rMPI (percent myocardium that was ischemic), patients with a normal adenosine rMPI had a cardiac mortality rate that varied from 0.4 to 5.3 percent per year in patients with a low and high prognostic score, respectively [74,75]. Similar risk stratification was seen among patients with a moderate to severely abnormal adenosine rMPI, in whom annual cardiac mortality varied from 3.9 to 7.6 percent per year in patients with a low and high prognostic score, respectively. (See 'Duke treadmill score' above.)
STRESS ECHOCARDIOGRAPHY
Exercise echocardiography — Exercise echocardiography provides independent prognostic information that is incremental to clinical, rest echocardiographic, and exercise ECG characteristics [77]. Of all exercise ECG and exercise echocardiographic variables, exercise capacity (ie, workload) and exercise wall motion score index had the strongest association with outcome, with a direct linear relationship between higher numbers of wall motion abnormalities and adverse cardiac events [77]. The incremental prognostic value of exercise echocardiography has also been demonstrated in older adults (≥65 years of age), in patients with diabetes mellitus, and in patients after coronary artery bypass surgery [78-80]. The predictive value of exercise echocardiography is enhanced by combining echocardiographic findings with other exercise test data [81-83].
A normal exercise echocardiogram identifies patients at low short-term cardiac risk [81,82,84]. In a report of 1325 patients with a normal stress echocardiogram, the one- and three-year cardiac event-free survival rates were 99 and 97 percent, respectively [82]. Similar findings were noted in a meta-analysis [84]. Event-free survival after a normal exercise echocardiogram in patients with known or suspected CHD was 98 percent at 33 months, with MI or cardiac death of only 0.54 percent per year. In a study of 4004 patients with interpretable ECGs who underwent stress treadmill echocardiography with no chest pain or ischemic ECG changes during the test (ie, normal exercise stress test result), ischemia was identified by echocardiography in 17 percent of patients [85]. The five-year mortality and major cardiac event rates were 6 and 4 percent in patients without ischemia and 12 and 10 percent in those with ischemia.
Dobutamine stress echocardiography — Dobutamine stress echocardiography provides independent prognostic information concerning possible future cardiac events that is incremental to clinical, rest echocardiographic, and exercise ECG characteristics [83,86-96]. The prognosis varies with the presence, severity, and extent of the induced ischemia and the heart rate at onset of myocardial ischemia (or ischemic threshold). Ischemia occurring at less than 60 percent of age-predicted maximal heart rate identified patients at highest risk for postoperative cardiac events.
In a review of 7333 consecutive patients referred for known or suspected CHD in whom pharmacologic stress echocardiography was performed and follow up to 200 months, overall survival was significantly lower in those with a positive test (59 versus 81 percent), with an estimated mortality of less than 1 percent per year in patients with a negative test [83]. The predictive value was additive to clinical variables and resting echocardiographic wall motion abnormalities.
Dobutamine stress echocardiography is predictive of events in patients with or without resting LV systolic dysfunction [97,98]. ST elevation during dobutamine stress echocardiography has also been associated with a higher risk of future cardiac adverse events [99].
In a study of 3156 patients who underwent dobutamine stress echocardiography and were followed for up to nine years, the number of abnormal territories at peak stress and the type of wall motion abnormality (ischemia or scar as defined by wall motion abnormalities occurring only during exercise or being present at rest, respectively) were independent predictors of cardiac events (figure 5A-B) [90].
Combination with Duke treadmill score — At a given Duke treadmill score on exercise ECG testing, the prognosis can be further stratified by the findings on concurrently performed exercise echocardiography or radionuclide myocardial perfusion imaging [59,81] and by a clinical determination of risk [60]. (See 'Normal rMPI' above.)
The combined utility of the Duke treadmill score and exercise echocardiography was illustrated in a study of 5375 patients with known or suspected CHD [81]. At a mean follow-up of 5.5 years, the following findings were noted:
●Among patients with a low-risk Duke treadmill score, the yearly mortality in those with a normal rest echocardiographic study, or evidence of disease in a single territory, or in multiple territories, was 0.7, 1.8, and 3 percent, respectively.
●Among patients with a moderate-risk Duke treadmill score, the yearly mortality in the three echocardiographic groups was 2.4, 3.7, and 7 percent, respectively.
●Among patients with a high-risk Duke treadmill score, the yearly mortality in the three echocardiographic groups was 4.6, 5, and 12 percent, respectively.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Chronic coronary syndrome" and "Society guideline links: Multimodality cardiovascular imaging appropriate use criteria" and "Society guideline links: Stress testing and cardiopulmonary exercise testing".)
SUMMARY AND RECOMMENDATIONS
●Prognostic role – Stress testing provides important prognostic information in patients with known or suspected coronary heart disease. (See 'Indications for stress testing for prognosis' above and "Selecting the optimal cardiac stress test", section on 'Indications for stress testing'.)
•Exercise stress testing provides more information about prognosis than pharmacologic stress testing. Exercise electrocardiogram (ECG) testing is the preferred method of stress testing in most patients. Exercise capacity is one of the most important determinants of prognosis. (See 'Exercise capacity' above.)
•Exercise-induced ST depression during exercise or recovery also has prognostic significance. (See 'Flat or downsloping ST depression' above.)
•Arrythmias
-Ventricular arrythmias during the recovery phase of stress testing are associated with worse cardiac outcomes and mortality, whereas less evidence suggests that premature ventricular complexes (PVCs) during exercise are associated with worse outcomes. PVCs in exercise stress testing are associated with a worse long-term prognosis in persons without underlying cardiac disease but do not provide further risk prediction over coronary angiography in persons with known coronary artery disease. (See 'Premature ventricular complexes' above.)
-Nonsustained ventricular tachycardia (NSVT) and atrial arrythmia during exercise are not associated with worse outcomes. (See 'Nonsustained ventricular tachycardia' above and 'Atrial arrhythmias' above.)
•Exercise-induced left bundle branch block may be associated with a worse-outcomes. (See 'Exercise-induced LBBB' above.)
●Heart rate responses to exercise stress – This also provides prognostic information, especially if the predicted exercise heart rate cannot be achieved or the heart rate does not promptly recover from peak levels after exercise. (See 'Heart rate response to exercise' above and 'Heart rate recovery after exercise' above.)
●Stress myocardial imaging – Stress testing with myocardial imaging using either radionuclide perfusion or echocardiography provides incremental prognostic information over clinical characteristics and exercise testing results. (See 'Radionuclide myocardial perfusion imaging' above and 'Stress echocardiography' above.)
●The Duke treadmill score – This uses three exercise parameters (exercise time, maximum ST segment deviation, and presence of angina) and is useful for stratifying patients into low-, moderate-, or high-risk categories for future cardiovascular events. (See 'Duke treadmill score' above.)
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