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Abnormal Athens QRS score in type II diabetes mellitus patients without evidence of coronary artery disease

K.Tsilias, N.Zamanis, A.Kranidis, G.Filippatos, E.Sioras, P.Anthopoulos, T.Fokaefs, S.Patsilinakos, L.Anthopoulos

1st Dept of Cardiology, Evangelismos Hospital
Athens, Greece

Abstract
Introduction
Purpose
Patients  and Methods
Results
Discussion
Conclusions
References

Abstract
Athens QRS score has been proposed as a new coronary artery disease index based on exercise induced QRS changes. It can be evaluated independently of ST-T changes. The purpose of our study was to assess Athens QRS score in diabetic patients with no evidence of ischemic heart disease.
Patients and methods The study included 33 normotensive type II diabetes mellitus patients (group A), of short duration (6.1 +/- 3.8 years), aged 52.9 +/-0.8 years and 34 healthy volunteers matched for age, gender and Body Mass Index (group B). All had no clinical and echocardiographic evidence of coronary artery disease, valvular and congenital heart disease, hypertension, left ventricular hypertrophy and arrhythmia. All subjects underwent treadmill stress testing using Bruce protocol, which was negative. Athens QRS score was calculated using the formula: Athens QRS score (mm) = (DR-DQ-DS)aVF + (DR-DQ-DS)V5 where DQ,DR and DS are Q,R and S wave differences obtained by subtracting the immediate postexercise Q,R and S wave amplitude values from the baseline in leads aVF and V5.
Results are summarized in the following table:
table.gif (2743 bytes)
Conclusions Type II Diabetics with negative Treadmill Stress Test and no other evidence of Coronary Artery Disease yield abnormal values for Athens QRS score, a finding that may have diagnostic and prognostic implications.

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Introduction:

The publication of a new diagnostic index for coronary artery disease, named Athens QRS score, in 1990, by Michaelides et al (1), has been an important step ahead in the diagnostic approach and in the severity estimation of coronary artery disease. The exercise induced QRS changes, on which Athens QRS score is based, can be evaluated independently of ST-T changes, on the standard treadmill stress test, using the Bruce protocol.

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Purpose:

The purpose of this study was to assess the Athens QRS score in diabetic type II patients, with no evidence of ischemic heart disease, either clinical or based on the standard treadmill stress test.

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Patients and Methods:

The study included 33 normotensive type II diabetes mellitus patients (group A) and 34 healthy volunteers (group B) who served as control group. Diabetes was diagnosed according to National Diabetes Data Group (2). Group A patients were aged 52.9± 10.8 years and suffered from diabetes mellitus of relatively short duration (6.1± 3.8 years). Group B subjects were mathced for age, gender and Body Mass Index. Both group A and B subjects had no clinical or echocardiographic evidence of coronary artery disease, valvular disease, hypertension, left ventricular hypertrophy, congenital heart disease and no arrhythmia history. Apart from the clinical and echocardiographic evaluation, all subjects successfully underwent treadmill stress testing using the multistage Bruce protocol on a Quinton 5000 treadmill (Quinton Instruments Co, Seattle, Wash.), which was negative by the standard criteria (3). Inconclusive test results were rejected. Athens QRS score was calculated using the formula: Athens QRS score (mm) = (DR-DQ-DS)aVF + (DR-DQ-DS)V5 where DQ,DR and DS are Q,R and S wave differences obtained by subtracting the immediate postexercise Q,R and S wave amplitude values from the baseline ones in leads aVF and V5. The amplitude of the R wave was measured from the isoelectric line to the peak of R wave. The amplitude of the Q and S waves was measured from the isoelectric line to the nadir of the Q and S waves respectively and the amplitude of each wave was approximated to the nearest 0.5 mm increment. The above formula and method are the original ones described by Michaelides et al (1). The treadmill stress testing duration in seconds (TST duration) was also calculated and the maximal systolic blood pressure (maximal SBP) reached, was recorded. Unpaired t-test was used for comparison of values obtained.

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Results:

The following table summarizes the findings
table.gif (2743 bytes)
All intergroup differences were not statistically significant except for the Athens QRS score, where p was found at the level of 0.004.

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Discussion:

According to previously reported data, by a Netherlands group (4), sensitivity, specificity and predictive accuracy of Athens QRS score are superior of the respective values of the ST segment depression. Also, the Athens QRS score values are independent of the exercise-induced ischemic changes and using this score, false negative (with no ischemic exercise ST segment changes) exercise test results can be identified (1). However the mechanism for the Athens QRS score changes is not yet fully understood. Factors other than myocardial ischemia, may play a role in causing these changes. These factors may include axis shift, left ventricular dysfunction, left ventricular enlargement and intraventricular conduction defects (1). Nevertheless, an abnormal Athens QRS score reflects myocardial ischemia (4).
The diabetic patients (group A) of this study were free of clinical and echocardiographic evidence of coronary artery disease, while they also exhibited negative treadmill stress test by the classical criteria. Therefore these patients would have not been advised to undergo any further diagnostic evaluation. Athens QRS score was actually indicative of the possible presence of coronary artery disease, in a group of patients that otherwise would have been considered normal regarding coronary artery disease treatment scopes. What is the meaning of the pathological Athens QRS score without ST segment abnormalities? Since we did not perform coronary angiography in our group A and B subjects, a definitive answer to the above question cannot be provided. A possible hypothesis is that, group A patients should generally have no severe coronary artery disease but they have impaired coronary flow reserve, as it was documented in a previous study from this group (5). Also Strauer et al, reported that diabetics with normal coronary angiograms have abnormal coronary flow reserve (6) possibly due to coronary microangiopathy. However, Strauer’s patients may be not directly comparable to ours (group A), as they had actually yielded clinical suspicion of coronary artery disease, while our group A patients did not.
It is clear that this study does not allow to draw definitive conclusions, but it should be regarded as a preliminary study, which could support the hypothesis that the Athens QRS score may reflect small vessel dysfunction. The next step, which will overcome the limitations of the presently available data, will be to perform coronary angiography and coronary flow reserve assessment, in order to definitively test the truth of our hypothesis.

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Conclusions:

Type II diabetics with negative treadmill stress testing and no other evidence of coronary artery disease yield abnormal values for the Athens QRS score. This may be an expression of small vessel dysfunction or disease, a hypothesis that merits further investigation in order to be tested.

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References

1. Michaelides AP, Triposkiadis FK, Boudoulas H, Spanos AM, Papadopoulos PD, Kourouklis KV, Toutouzas PK. New coronary artery disease index based on exercise induced QRS changes. Am Heart J 1990;120:292.
2. National Diabetes Data Group. Classification and diagnosis of diabetes mellitus and other categories of glucose intolerance. Diabetes 1979;28:1039-1057.
3. Braunwald E (ed.). Heart Disease, a textbook of cardiovascular medicine. 5th Edition. WB Saunders Company, Philadelphia 1997, pp. 153-176.
4. Van Campen CMC, Visser FC, Visser CA. The QRS score: a promising new exercise score for detecting coronary artery disease based on exercise induced changes of Q-, R- and S-waves: a relationship with myocardial ischemia. Eur Heart J 1996: 17: 699-708.
5. Kranidis A, Zamanis N, Mitrakou A, Patsilinakos S, Bouki T, Tountas N, Anthopoulos P, Raptis S, Anthopoulos L. Coronary microcirculation evaluation with transesophageal echocardiography Doppler in type II diabetics. Int J Cardiol 1997;59(2):119-124.
6. Strauer BE, Motz W, Vogt M, Schwartzkopff B. Impaired coronary flow reserve in NIDDM. A possible role for diabetic cardiopathy in humans. Diabetes 1997;46 Suppl 2: S119-S124.

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Questions, contributions and commentaries to the Authors: send an e-mail message (up to 15 lines, without attachments) to coronary-pcvc@pcvc.sminter.com.ar , written either in English, Spanish, or Portuguese.

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