Letter to the Editor Re: Krishnaswamy

Fiol, Miquel; Carrillo, Andrés; de Luna, Antonio Bayés

doi:10.1016/j.ahj.2010.04.001

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Volume 160, Issue 1 , Page e5, July 2010

Letter to the Editor Re: Krishnaswamy

Coronary Care Unit, University Hospital Son Dureta and Institut of Health Sciences (IUNICS), Palma de Mallorca, Spain

Centre Català d'Investigacio Cardiovascular, Hospital Sant Pau, Barcelona, Spain

To the Editor:

Krishnaswamy et al¹ has described the difficulty for the diagnosis of the left circumflex artery (LCx) occlusion in the early phases of the acute myocardial infarction. In the Figure 1 of their article, the electrocardiogram (ECG) may be considered normal, but the coronary angiography was performed some hours later when the ECG can be changed, and moreover, in cases of occlusion of first obtuse marginal branch, the ECG often is normal. It is known that the electrocardiographic criteria, which are summarized in Table II,¹ has a sensitivity very limited when used isolated as it has been in our experience (Table I).² This is why we believe that an algorithm should be used in several steps involving several criteria. Thus with the use of our algorithm in 3 steps, the accuracy to locate of the culprit coronary artery is 95% of cases. The few patients in whom this algorithm did not work were those with a very dominant LCx.

Table I. Electrocardiographics isolated and global (algorithm) indicators of LCx occlusion in our experience²

Criteria	Sensitivity (%)	Specificity (%)	Positive predictive value (%)	Negative predictive value (%)
ST-segment elevation (≥0.5 mm) in lead I	31	100	100	85
ST-segment elevation in lead II > III	69	92	69	92
ST-segment depression in ∑V₁ to V₃ > ∑ II, III, VF	61	94	73	90
Global (sequential 3 steps)	80	100	100	94.3

It is true that, often, patients are catalogued as non–ST-segment elevation acute coronary syndrome and therefore not benefit from an early reperfusion, but this is a problem of clinical experience. We suggest that in patients with prolonged angina and depressed ST in V₁ to V₃ should be considered atypical ST-segment elevation acute coronary syndrome (mirror pattern).³, ⁴ The practice of derivations V₇ to V₉ can confirm this diagnosis by looking at an elevation of ST.

Therefore, the easiest and cheaper strategy for diagnosing LCx occlusion is to use the information properly taken from surface ECG. We do not need to use sophisticated surface body mapping or echocardiography because the global predictive value of our approach is around 95%.

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References

Krishnaswamy A, Lincoff M, Menon V. Magnitude and consequences of missing the acute infarct-related circumflex artery. Am Heart J. 2009;158:706–712

Fiol M, Cygankiewicz I, Carrillo A, et al. Value of electrocardiographic algorithm based on “ups and downs” of ST in assessment of a culprit artery in evolving inferior wall acute myocardial infarction. Am J Cardiol. 2004;94:709–714

In: Bayés de Luna A, Fiol-Sala M editor. Electrocardiography in ischemic heart disease. Oxford: Blackwell-Futura Publishing; 2008;p. 211
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Nikkus K, Pahlm O, Wagner G, et al. Electrocardiographic classification of acute coronary syndromes: a review by a committee of the International Society for Holter and Non-Invasive Electrocardiology. J Electrocardiol. 2010;43:91–103

PII: S0002-8703(10)00317-0

doi:10.1016/j.ahj.2010.04.001

Refers to article:

Magnitude and consequences of missing the acute infarct-related circumflex artery , 25 September 2009
Amar Krishnaswamy, A. Michael Lincoff, Venu Menon
American Heart Journal November 2009 (Vol. 158, Issue 5, Pages 706-712)