Global research for health should tackle health needs and inform policy

In the linked cohort study, Sekhri and colleagues assess whether resting and exercise electrocardio‐ grams (ECGs) provide superior prognostic value to that obtained from the clinical history in ambulatory patients with suspected angina.1 The study indicates that the clinical assessment accounts for most of the prognostic information provided by resting and exer‐ cise ECGs. Other studies and algorithms have used the patient’s pretest probability to help with diagnosis,2 but long term prediction of risk and the incremental usefulness of the ECG have not been evaluated in this way. The study is a reminder of the importance of tak‐ ing a detailed history and making a thorough physical examination, and that additional information from the ECG is helpful in some patients but does not predict risk in everyone. The results do not mean that ECGs and stress tests are not useful, because an abnormal ECG and abnormal stress test independently predicted adverse events, such as death or acute coronary syndrome in the cohort studied. Some patients with normal ECGs and stress test results subsequently had cardiovascular events; this shows that predicting risk in the longer term is difficult. In most patients presenting to a chest pain clinic a diagnosis is made on the basis of the history and examination. For example, a 55 year old man with classic exertional angina that is relieved with rest or nitroglycerine needs no further tests to confirm the diagnosis of coronary dis‐ ease. However, a test is needed to distinguish between the shorter term and longer term prognosis, especially in people who have a normal stress test result but who sub‐ sequently have cardiovascular events (although Sekhri and colleagues’ study indicates that the event rate is lower in these patients than in those with abnormal results). Attempts have been made at fine tuning the prognos‐ tic value of the basic treadmill test. Research in North America showed that the Duke treadmill score added prognostic information to a routine stress test.3 Other modalities, such as exercise echocardiography, have been added more recently to the Duke treadmill score to predict risk.4 Sekhri and colleagues also found that the duration of exercise is a stronger predictor than other variables in the model of future cardiovascular events. More sophisti‐ cated tests to assess left ventricular function and perfusion with stress imaging also have greater negative predictive value than a routine stress test.5‐8 However, from a popu‐ lation perspective this may be an unnecessary expense, and these tests may be more useful in selected groups of patients8 who have a higher pretest probability. Sekhri and colleagues’ study shows that although the short term cardiovascular event rates are lower in patients with a normal ECG and stress test, they are not zero. So the study cannot provide an answer about which approach should be used in patients with a normal ECG. These patients need to have their cardiac risk factors assessed regularly by their general practitioner, and if necessary modified. As the authors correctly say, the stress test and ECG are not foolproof predictors of risk, and other methods need to be tested. However even though these tests cannot predict all future events, they are a necessary extension of the physical examination in patients with suspected angina. Sekhri N, Feder GS, Junghans C, Eldridge S, Umaipalan A, Madhu R, 1 et al. Incremental prognostic value of the exercise electrocardiogram in the initial assessment of patients with suspected angina. BMJ 2008;337:a2240. Brister SJ, Turek MA, eds. Canadian Cardiovascular Society 2000 2 consensus conference: women and ischemic heart disease. Can J Cardiol 2001;17(suppl D):38D-48D. Mark DB, Shaw L, Harrell FE Jr, Hlatky MA, Lee KL, Bengtson JR, et al. 3 Prognostic value of a treadmill exercise score in outpatients with suspected coronary artery disease. N Engl J Med 1991;325:849-53. Marwick TH, Case C, Vasey C, Allen S, Short L, Thomas JD. Prediction 4 of mortality by exercise echocardiography: a strategy for combination with the Duke treadmill score. Circulation 2001;103:2566-71. Vanzetto G, Ormezzano O, Fagret D, Comet M, Denis B, Machecourt 5 J. Long-term additive prognostic value of thallium-201 myocardial perfusion imaging over clinical and exercise stress test in low to intermediate risk patients: study in 1137 patients with 6-year followup. Circulation 1999;100:1521-7. Valeti US, Miller TD, Hodge DO, Gibbons RJ. Exercise single-photon 6 emission computed tomography provides effective risk stratification of elderly men and elderly women. Circulation 2005;111:1771-6. Gehi AK, Ali S, Na B, Schiller NB, Whooley MA. Inducible ischemia 7 and the risk of recurrent cardiovascular events in outpatients with stable coronary heart disease: the heart and soul study. Arch Intern Med 2008;168:1423-8. Marwick TH, Case C, Sawada S, Rimmerman C, Brenneman P, Kovacs 8 R, et al. Prediction of mortality using dobutamine echocardiography. J Am Coll Cardiol 2001;37:754-60. vo is in /P h an ie /r ex f ea tu re s REsEaRch, p 1272