Guidelines on the Management of Stable Angina Pectoris ... - Cardio

ESC <strong>Guidelines</strong> 9Recommendations for resting ECG for initial diagnosticassessment of anginaClass I (in all patients)(1) Resting ECG while pain free (level of evidence C)(2) Resting ECG during episode of pain (if possible) (level ofevidence B)Recommendations for resting ECG for routine reassessmentin patients with chronic stable anginaClass IIb(1) Routine periodic ECG in the absence of clinical change(level of evidence C)ECG stress testingExercise ECG is more sensitive and specific than the restingECG for detecting myocardial ischaemia 134,135 and forreasons of availability and cost is the test of choice to identifyinducible ischaemia in the majority of patients withsuspected stable angina. There are numerous reportsand meta-analyses of the performance of exercise ECGfor the diagnosis of coronary disease. 136–139 Using exerciseST-depression ,0.1 mV or 1 mm to define a positive test,the reported sensitivity and specificity for the detection ofsignificant coronary disease range between 23–100% (mean68%) and 17–100% (mean 77%), respectively. Excludingpatients with prior MI, the mean sensitivity was 67% andspecificity 72%, and restricting analysis to those studiesdesigned to avoid work-up bias, sensitivity was 50% and specificity90%. 140 The majority of reports are of studies where thepopulation tested did not have significant ECG abnormalitiesat baseline and were not on antianginal therapy or were withdrawnfrom antianginal therapy for the purposes of the test.Exercise ECG testing is not of diagnostic value in the presenceof LBBB, paced rhythm, and Wolff–Parkinson–White (WPW)syndrome, in which cases, the ECG changes cannot be evaluated.Additionally, false-positive results are more frequent inpatients with abnormal resting ECG in the presence of LVH,electrolyte imbalance, intraventricular conduction abnormalities,and use of digitalis. Exercise ECG testing is also less sensitiveand specific in women. 141Interpretation of exercise ECG findings requires a Bayesianapproach to diagnosis. This approach uses clinicians’pre-test estimates of disease along with the results of diagnostictests to generate individualized post-test diseaseprobabilities for a given patient. The pre-test probabilityis influenced by the prevalence of the disease in the populationstudied, as well as clinical features in an individual. 142Therefore, for the detection of coronary disease, thepre-test probability is influenced by age and gender andfurther modified by the nature of symptoms at an individualpatient level before the results of exercise testing are usedto determine the posterior or post-test probability, asoutlined in Table 4.In populations with a low prevalence of ischaemic heartdisease the proportion of false-positive tests will be highwhen compared with a population with a high pre test probabilityof disease. Conversely, in male patients with severeeffort angina, with clear ECG changes during pain, thepretest probability of significant coronary disease is high(.90%), and in such cases, the exercise test will not offeradditional information for the diagnosis, although it mayadd prognostic information.A further factor that may influence the performance ofthe exercise ECG as a diagnostic tool is the definition of apositive test. ECG changes associated with myocardialischaemia include horizontal or down-sloping ST-segmentdepression or elevation [1 mm (0.1 mV) for 60–80 msafter the end of the QRS complex], especially when thesechanges are accompanied by chest pain suggestive ofangina, occur at a low workload during the early stages ofexercise and persist for more than 3 min after exercise.Increasing the threshold for a positive test, for example,to 2 mm (0.2 mV) ST-depression, will increase specificityat the expense of sensitivity. A fall in systolic pressure orlack of increase of blood pressure during exercise and theappearance of a systolic murmur of mitral regurgitation orventricular arrhythmias during exercise reflect impaired LVfunction and increase the probability of severe myocardialischaemia and severe CAD. In assessing the significance ofthe test, not only the ECG changes but also the workload,heart rate increase and blood pressure response, heartrate recovery after exercise, and the clinical contextshould be considered. 143 It has been suggested that evaluatingST changes in relation to heart rate improves reliabilityof diagnosis 144 but this may not be so in symptomaticpopulations. 145–147An exercise test should be carried out only after carefulclinical evaluation of symptoms and a physical examinationincluding resting ECG. 135,140 Complications during exercisetesting are few but severe arrhythmias and even suddendeath can occur. Death and MI occur at a rate of less thanor equal to one per 2500 tests. 148 Accordingly, exercisetesting should only be performed under careful monitoringin the appropriate setting. A physician should be presentor immediately available to monitor the test. The ECGshould be continuously recorded with a printout at preselectedintervals, mostly at each minute during exercise,and 2–10 min of recovery after exercise. Exercise ECGshould not be carried out routinely in patients with knownsevere aortic stenosis or hypertrophic cardiomyopathy,although carefully supervised exercise testing may be usedto assess functional capacity in selected individuals withthese conditions.Either the Bruce protocol or one of its modifications on atreadmill or a bicycle ergometer can be employed. Mostconsist of several stages of exercise, increasing in intensity,either speed, slope, or resistance or a combination of thesefactors, at fixed intervals, to test functional capacity. It isconvenient to express oxygen uptake in multiples ofresting requirements. One metabolic equivalent (MET) is aunit of sitting/resting oxygen uptake [3.5 mL of O 2 per kilogramof body weight per minute (mL/kg/min)]. 149 Bicycleworkload is frequently described in terms of watts (W).Increments are of 20 W per 1 min stage starting from 20 to50 W, but increments may be reduced to 10 W per stage inpatients with heart failure or severe angina. Correlationbetween METs achieved and workload in watts varies withnumerous patient-specific and environmental factors. 135,150The reason for stopping the test and the symptoms at thattime, including their severity, should be recorded. Time tothe onset of ECG changes and/or symptoms, the overallexercise time, the blood pressure and heart rate response,the extent and severity of ECG changes, and the postexerciserecovery rate of ECG changes and heart rateshould also be assessed. For repeated exercise tests, the