Intended for healthcare professionals

Rapid response to:

Papers

Trends in rates of different forms of diagnosed coronary heart disease, 1978 to 2000: prospective, population based study of British men

BMJ 2005; 330 doi: https://doi.org/10.1136/bmj.330.7499.1046 (Published 05 May 2005) Cite this as: BMJ 2005;330:1046

Rapid Response:

Trends in rates of angina: real incidence increase or improved diagnostic sensitivity?

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

Competing interests: No competing interests

12 May 2005
Giuseppe Lippi
Associate Professor
Martina Montagnana, Gian Luca Salvagno, Gian Cesare Guidi.
Ist. Chimica e Microscopia Clinica, Verona University, ITALY