Perspectives on the Future of Stress Testing

The chapter Perspectives on the Future of Stress Testing forecasts changes in the ability to detect atherosclerosis in the form of obstructive and non-obstructive coronary artery disease and ischemia. These will continue to include low cost and widely available exercise testing as well as embracing new technology such as mobile sensors, biomarkers, and genetic testing. Continued advancements in positron emission tomography, cardiac computed tomography, and cardiac magnetic resonance imaging will create new opportunities for better definition of myocardial blood flow and prediction of prognosis. While we will continue to expand our ability to measure greater detail of aspects of cardiac structure, function and metabolism, the humanity of a clinician being at the side of the treadmill while our whole patients exercise to their individual capacity remains a valuable diagnostic, educational and bonding opportunity

Heart Rate Response to Exercise

The chapter Heart Rate Response to Exercise reviews the studies performed to estimate a patient’s maximum predicted heart rate. While the commonly used formula (220 – age), developed in 1971, is easy to remember, it underestimates the actual maximum heart rate in older persons. Studies of large sample size have found the maximum heart rate to be relatively independent of sex and physical fitness but to incrementally decline with age. The decrease with age is less than 1 beat per minute per year, however. A more accurate and recommended formula is [(208) – (0.7)(age)] as developed by Tanaka and colleagues.

Cardiopulmonary Exercise Testing

The chapter Cardiopulmonary Exercise Testing focuses on the opportunities provided by cardiopulmonary exercise (CPX) testing. The coordination of 5 organ systems is described in normal exercise physiology to understand abnormal exercise findings. From a few measured expired gas analysis parameters, most of the important exercise variables can be derived, including the peak oxygen consumption (peak VO2). The contribution of both the aerobic and anaerobic phases of exercise to total exercise capacity are described, including the methods for determination of the anaerobic threshold. The calculation of the normative values of peak VO2 are included, and a suggested template of a CPX report is included. The use of CPX testing in the determination of prognosis in heart failure patients is included.

Stress Cardiac Magnetic Resonance Imaging

The chapter Stress Cardiac Magnetic Resonance Imaging reviews how cardiovascular magnetic resonance imaging (CMR) has become a gold standard for evaluating stress induced wall motion abnormalities based on regional endocardial excursion and myocardial thickening. The high spatial and temporal resolution of CMR without limitations imposed by body habitus and acoustic windows allows outstanding visualization of myocardial function. CMR can also be combined with vasodilator stress to perform dynamic first-pass myocardial perfusion imaging. The addition of late gadolinium enhancement allows the accurate of nonviable scar tissue in combination with wall motion and myocardial perfusion assessment. Case studies highlight the opportunity provided by stress CMR.

Stress Echocardiography

The Stress Echocardiography chapter reviews the opportunities to increase sensitivity and specificity of stress testing for the diagnosis of ischemic heart disease with adjunctive echocardiography with exercise or dobutamine-atropine stress. Baseline imaging prior to stress should include a comprehensive evaluation of cardiac structure and function, including the assessment of valvular disease with Doppler echocardiography. The chapter discusses stress echocardiography protocols; image analysis and reporting; sensitivity, specificity, and accuracy for detection of coronary artery disease; and evaluation of noncoronary cardiac disease. New and developing echocardiographic technology, including ultrasound assessment of myocardial perfusion, real-time 3D echocardiographic, and strain imaging are also discussed.

Rhythm and Conduction Disturbances in Stress Testing

The chapter Rhythm and Conduction Disturbances in Stress Testing reviews the frequency and significance of arrhythmias and conduction abnormalities precipitated by exercise. Case examples are provided. PVCs occurring prior to, during exercise, or during recovery all modestly increase the risk of all-cause mortality in patients with and without known coronary artery disease (CAD). Ventricular tachycardia and premature ventricular complexes are often not reproducible on a subsequent exercise test. Exercise induced left bundle branch block (LBBB) predicts increased risk of the presence of CAD, all cause mortality, and often permanent LBBB. Differentiating wide complex tachycardia during exercise testing between supraventricular tachycardia and ventricular tachycardia can be challenging. The Wellens, Brugada, and Vereckei algorithms to distinguish between these arrhythmias are detailed and compared.

Parameters to Be Measured during Exercise

The chapter Parameters to be Measured During Exercise reviews the physiologic changes with exercise which indicate health and disease. Key parameters include blood pressure, heart rate, electrocardiographic changes, exercise duration, maximum oxygen uptake (VO2max), and anaerobic threshold. An in-depth review and consensus estimate is provided to estimate metabolic equivalents (METs) achieved based on exercise duration on the Bruce and Ellestad protocols. Use of bipolar leads for detection of exercise induced myocardial ischemia is discussed, typified by CM5 which captures up to 90% of patients with an electrocardiographic manifestation of ischemia. Changes in murmurs that occur with exercise are reviewed; walk-through angina and chronotropic incompetence.

Stress Testing in Children

The chapter Stress Testing in Children reviews the opportunity to evaluate children with congenital and acquired cardiovascular disease. Clinical pediatric exercise testing differs from adult testing in both disease etiology as well as the characteristics of cardiovascular response. Unlike exercise testing in adults, the indications for testing in pediatrics generally are not to evaluate for ischemia. Commonly, pediatric exercise testing is used to evaluate specific signs and symptoms induced or aggravated by exercise, including identification of exercise induced arrhythmias, whereas metabolic testing can provide further patient information regarding cardiac output, maximal oxygen consumption, and lung capacity. Exercise testing can also assess the efficacy of medical or surgical treatments for individual congenital heart disease patients. Functional capacity can be used to determine patient safety for recreational, athletic, and vocational activities. Exercise modification and restrictions are necessary for some patients based on the data provided by exercise testing.

Sports Medicine and Cardiac Rehabilitation for Coronary and Peripheral Artery Disease Patients

The chapter Sports Medicine and Cardiac Rehabilitation for Coronary and Peripheral Artery Disease (CAD) reviews the benefits and potential risks of physical activity and the opportunity for particular benefit in patients with coronary artery disease and peripheral artery disease (PAD). Longitudinal studies of large populations have found a benefit to habitual exercise on cardiovascular health, including decreasing cardiovascular mortality. A physiologic training effect is not required for benefit. Mild exercise is better than inactivity and increasing activity provides even greater benefit. Athletic training induces expected electrocardiographic changes at rest in athletes. Prescribing exercise with or without an exercise test is discussed in asymptomatic individuals as well as prior to participation in traditional cardiac rehabilitation or a supervised exercise program for patients with peripheral artery disease. PAD patients often do not have classic intermittent claudication yet are able to benefit from exercise therapy.

Metabolic Abnormalities and Drugs

The chapter Metabolic Abnormalities and Drugs reviews the changes that affect the electrocardiogram at rest and during exercise. Anticipating these changes often allows the exercise test to remain diagnostic without the need for adjunctive imaging. Changes between rest and exercise occur with metabolic acidosis, alkalosis, hyperthyroidism, hypothyroidism, estrogens, androgens, digoxin, diuretics, nitrates, ranolazine, dipyridamole, beta blockers, calcium channel blockers, anti-hypertensive agents, ivabradine, alcohol, nicotine, catecholamines, amphetamines, selective serotonin reuptake inhibitors, tricyclic antidepressants, lithium, and many anti-arrhythmics including quinidine, disopyramide, sotalol, flecainide, dofetilide, amiodarone, and dronedarone. Careful integration of all clinical variables, aided by the use of tools such as the Duke Treadmill Score, can reduce the need for additional testing including coronary angiography.