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Trends in rates of angina: real incidence increase or improved diagnostic sensitivity?
- Giuseppe Lippi, Martina Montagnana, Gian Luca Salvagno, Gian Cesare Guidi. (12 May 2005)
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Angina is a symptom
- Caroline E Morrison, Glasgow G3 8YZ (30 June 2005)
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Giuseppe Lippi, Associate Professor Ist. Chimica e Microscopia Clinica, Verona University, ITALY, Martina Montagnana, Gian Luca Salvagno, Gian Cesare Guidi.
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Dear Editor, The article of Lampe and colleagues, recently appeared on this Journal, highlights the progressive decline in the rate of major coronary events among British men over a 20 year period, a rather favorable trend, which was surprisingly offset by an increased rate of new angina diagnoses (1). Such an increase appeared larger for angina diagnosed after myocardial infarction. The diagnostic approach to the acute coronary syndrome (ACS) and the acute myocardial infarction (AMI) has been one of the most challenging and intriguing medical issue for long (2). At the time of the original definition of AMI, issued by the World Health Organization in 1971 (3), the contribution of laboratory testing to the diagnosis of AMI was confined to the enzymatic determination of aspartate aminotransferase, lactate dehydrogenase and creatine kinase. Any serum increase in the activity of these enzymes was intended as a useful tool to identify a muscular injury, rather than serve as a definitive proof of myocardial involvement. This situation remained mostly unchanged for roughly two decades. By mid 90s, however, the discovery of cardiospecific proteins of the sarcomeric pool, the troponins, disclosed a novel and revolutionary diagnostic scenario. Owing to improved sensitivity and greater tissue specificity, the troponins evolved into the most important markers for ACS, turning out as biochemical “gold standards" for the management of patients with acute chest pain. Most immunological assays for cardiospecific troponins currently allow detection of minimal concentrations in plasma, enabling quantitative detection of much smaller amounts of myocardial injury than before. A negative troponin measurement might place patients at lower risk for a cardiac ischemic event within few hours from admission to an emergency department. Conversely, a positive value would put the individual at a much higher risk, and a more substantial proportion of patients can now be diagnosed has having an ACS, as compared to the early ‘80s, including those presenting with angina. This might be a crucial point when analyzing results shown by Lampe et al. In their study, the diagnoses of angina did not require fulfillment of specific objective criteria and therefore reflected diagnoses occurring in clinical practice. The hypothesized contribution of novel diagnostic investigations for angina-like chest pain might be really critic, introducing an uncontrolled bias in the statistical analysis of data. On this basis, we can not rule out that the reported trend in rates of angina over a 20 year period might reflect an improved diagnostic sensitivity rather than a real incidence increase. References 1. Lampe FC, Morris RW, Walker M, Shaper AG, Whincup PH. Trends in rates of different forms of diagnosed coronary heart disease, 1978 to 2000: prospective, population based study of British men. BMJ 2005;330:1046. 2. Rosalki SB, Roberts R, Katus HA, Giannitsis E, Ladenson JH. Cardiac biomarkers for detection of myocardial infarction: perspectives from fast to present. Clin Chem 2004;50:2205–13. 3. Fox KAA, Birkhead J, Wilcox R, Knight C, Barth J. British Cardiac Society Working Group on the definition of myocardial infarction. Heart 2004;90:603–9. Competing interests: None declared |
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Caroline E Morrison, Consultant in Public Health Dalian House, 350 St Vincent Street, Glasgow G3 8YZ
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Lampe and colleagues suggest that a difference in diagnostic threshold would account for the increase in new diagnoses of angina and the fall in reported angina in questionnaires. There may be another explanation. The increase in the use of antianginal medication and coronary intervention, particularly angioplasty, may account for fewer patients with coronary heart disease reporting symptoms recently compared with some years ago. The first presentation would still be chest pain, but there is a greater chance of fewer patients continuing to have symptoms. Competing interests: None declared |
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