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This study is undertaken to test the hypothesis that biphasic inversion of T-waves in precordial leads on electrocardiogram is associated with severe stenosis in the proximal part of left anterior descending coronary artery (LAD), in patients with ischemic heart disease (IHD).
A prospective, case-controlled, observational study was carried out at National Institute of Cardiovascular Diseases (NICVD), Karachi from the month of February till August, 2009. A total of 100 consecutive patients with history of ischemic heart disease and undergoing coronary angiography were included. Using convenience sampling, data was collected with the aid of a questionnaire to assess the coronary risk factors and angiographic findings were recorded during cardiac catherization of the patients.
All the data collected was sorted and analyzed on MS Excel and SPSS version 16 for statistical analysis.
Results: Biphasic T-wave inversion was seen in leads v1-v3 in 90% of the patients, while the remaining showed these changes in leads v4-v6. Angiographic findings revealed that majority of the patients (50%) had coronary artery stenosis in the proximal part of LAD, while 20% showed the occlusion in the middle part. Right coronary artery established the dominance of the heart in 75% of the patients and two-vessel disease was most commonly observed during cardiac catherization.
Conclusion: Early intervention with subsequent PCI or CABG is essential for patients who show the classical presentation of Wellen's syndrome on ECG, although this ECG pattern may not be well defined during the symptomatic phase of acute ischemia and hence, maybe overlooked.
Keywords: Wellen's syndrome, T-wave inversion, Coronary Angiography
Few case-reports have demonstrated a strong association between biphasic inversion of T-waves in precordial leads on ECG with severe stenosis in the proximal part of left anterior descending coronary artery (LAD) in patients with ischemic heart diseases (IHD). Our aim in this study is to observe the significance of these subtle, easily ignored electrocardiography findings with LAD stenosis in our population, where cost is the major constrain.
Wellens' syndrome is a characteristic pattern of T-wave changes on electrocardiogram indicating a high-grade stenosis of proximal left anterior descending coronary artery (LAD) in patients with unstable angina, at a time when there is no pain [1-4]. The T-wave findings in anterior leads can take various forms of appearance, most commonly present in one of the two forms; in approximately 75% of the cases, T-waves are deeply inverted (>2mm) with a symmetrical contour, while in the remaining 25%, T-waves are biphasic [4, 5]. During episodes of angina, the inverted or biphasic T-waves normalize with either ST-elevation or depression, the time when the coronary vessel is significantly narrowed or occluded . The diagnostic leads for T-wave changes in this syndrome are v2 and v3, indicating the typical occlusion between the first and second septal branches of LAD, although this occlusion can be more proximal with more widespread changes in T-wave on ECG . Cardiac biomarkers are not help in diagnosis as they are usually within the normal range, or mildly elevated, except in 12% patients and even in these the values are usually less than twice the upper limit of normal . Syndrome criteria also include history of angina, lack of pathological Q waves and normal precordial R-wave progression. In 1982, Wellens et al. demonstrated in their study that 75% of the patients with this typical syndrome manifestations who were not revascularized developed an extensive anterior wall MI within a few weeks after admission, even when on medical treatment , thus signifying the dominance of Percutaneous Intervention (PCI) over medical therapy alone. Performance of stress tests may prove to be fatal for these patients as the severe stenosis can lead to infarction at the time of increased cardiac demand. This makes urgent coronary angiography with subsequent Percutaneous Coronary Intervention (PCI) or Coronary Artery Bypass Graft (CABG) essential for patients who show this ECG pattern .
SUBJECT AND METHODS:
A prospective, case controlled, observational study was carried out in the cath lab of National Institute of Cardiovascular Diseases (NICVD), Karachi between the months February 2009 to August 2009.
Using convenience sampling, a sample size of 100 patients between the ages of 44 and 62 years with a history of ischemic heart disease and with ECG features of biphasic T waves inversion in precordial leads admitted in National Institute of Cardiovascular Diseases and scheduled for the procedure of coronary angiography were included.
All subjects were individually contacted, interviewed and the appropriate questions asked. Detailed clinical history and examination was also carried out with particular reference to hypertension, diabetes, smoking, socioeconomic status, lifestyle, family history of ischemic heart disease, obesity, waist to hip ratio and other coronary risk factors. Electrocardiogram, fasting and postprandial blood sugar, fasting lipid profile and cardiac catheterization was done in every subject.
All male and female candidates between the set age limit presenting with symptoms of ischemic heart disease and ECG showing biphasic inverted T-waves were taken into account. Care was taken to include patients with hypertension, diabetes mellitus, dyslipidemia, cardiac failure, stable angina, unstable angina and patients who had suffered from acute myocardial infarction, both symptomatic and silent.
Patients with valvular heart diseases, ventricular hypertrophy, congenital heart diseases, atrial fibrillation, atrial flutter, heart block, pre-excitation syndrome and bundle branch block were not included. Furthermore, patients with history of uncontrolled hypertension, decompensated congestive heart failure, refractory arrythmia, CVA, coagulopathy, GI haemorrhage, renal failure, pregnancy, active infection, contrast medium allergy or those showing refusal to give informed consent were excluded from the study.
With the aid of a precise questionnaire, many important variables including age were extracted, which were linked to the patients' number of blocked arteries and the ECG findings. In addition, the questionnaire was designed to gather information pertaining to the subject's risk factors.
The study did not involve any follow-up on the subjects. The data from each individual was collected only during their initial cardiac catheterization.
The procedure of coronary angiography was performed using either the radial or the femoral artery. Dominance of the heart was determined as right, left or co-dominant. 70% stenosis of the arterial luminal diameter (in any view) was considered a significant lesion. As a trend needed to be established between LAD in relation to T-wave inversion, lesions of LAD recorded as Proximal, Mid, Distal, Osteal, Proximal + Distal, Mid + Distal, Left Main Stenosis were accounted for as separate variables. If a patient had stenosis in two consecutive segments then the proximal segment was included. On the basis of lesions diagnosis of SVD, 2VD and 3VD was made. Left main coronary lesions were counted when the luminal diameter was reduced by 50%.
The data collected was sorted and analyzed on MS Excel and SPSS version 16. Age was presented as mean ± SD and independent t test was used to compare mean age b/w biphasic t wave groups. Categorical variables like dominance, LAD and diagnosis were presented in frequencies and percentages and chi square test was used to evaluate significant association b/w biphasic T-wave groups and categorical variables. P value less than 0.05 was considered as statistically significant.
A total of 100 patients fulfilled the inclusion criteria. 90 patients (90%) showed biphasic T-wave inversion in leads v1-v3 (Group 1), whereas the remaining 10 patients (10%) showed these changes in leads v4-v6 (Group 2). Mean age was higher in Group 1 (53.8 ± 9.1) than the other biphasic T-wave group (51.1 ± 10.1); range 44-62 years. (Table-1)
In both groups, right coronary artery established the dominance of the heart (n=75, 75%), being more common in Group 1 (77.8%) than Group 2 (50%). 14 patients out of the total (14%) showed co-dominance and 11 patients (11%) had left-sided dominance. (Figure-1)
The most common site of lesion was proximal LAD, seen in 50 patients (50%). In Group 1, proximal LAD stenosis was present in 49 out of 90 patients (54.4%), and in 1 out of 10 patients (10%) in Group 2 (p=0.008). However, in 20% of the total patients, coronary lesion was found in middle part of LAD.
It was seen that two-vessel coronary disease (2VD) was present in majority (41%) of the patients. In Group 1, 2VD was present in 38 out of 90 patients (42.2%), and in Group 2, it was noted in 3 out of 10 patients (30%). Single-vessel disease was found in 29 patients (29%); 27 patients (30%) in Group 1 and in 2 patients (20%) in Group 2. Three-vessel disease (3VD) was noted in 28 patients (28%), being in an almost similar ratio in the two groups; 27.8% in Group 1 and 30% in Group 2. Left Main Artery disease was seen in only 2 patients from Group 1 (p=0.001).
Figure 1: Dominance of heart as seen in Group 1 (leads v1-v3) and Group 2 (leads v4-v6)
Characteristic biphasic T-wave changes in precordial leads without Q-waves in a pain-free period is called Wellens' syndrome and is associated with severe proximal LAD stenosis, hence also termed as LAD Coronary T-wave syndrome . In patients admitted with unstable angina, this characteristic ECG pattern is not a rare finding, present in 14-18% of the cases [1, 6]. The term was coined for the first time by Tilkian , representing a pre-infarction stage of CAD (coronary artery disease) . Since the LAD supplies the anterior myocardium, patients with this T-wave pattern on ECG are at a high risk of development of extensive infarction of the anterior wall, with a mean time of approximately 8.5 days from the onset of Wellens syndrome to infarction . Stress test is contraindicated as there is minimal collateral circulation to compensate for a large part of the anterior myocardium, thus precipitating an acute MI. These patients require immediate coronary angiography, revascularization strategies and aggressive medical management . de Zwaan et al. showed gradual disappearance of characteristic T-wave findings in the ECG after revascularization, hence indicating successful PCI .
As seen in our study, biphasic T-waves of Wellens' syndrome are most commonly observed in leads v1-v3. Similar studies have affirmed leads v2 and v3 to be the diagnostic leads for biphasic T-waves, leads v4-v6 being less common [6, 9]. In a study by Vanpee et al., it was highlighted that biphasic T-waves may represent critical stenosis in the artery related to the leads in which these specific changes are seen .
The T-wave changes may persistently remain for hours or weeks . As mentioned above, the presence of these characteristic T-wave changes in patients with unstable angina is predictive of significant coronary artery stenosis, and identifies a subgroup with poor prognosis when on medical therapy . Coronary angiographic findings demonstrated that the most common site for coronary vessel occlusion was proximal LAD. Rhinehardt et al. showed in their study that in 83% of the cases, LAD occlusion site was found proximal to the second septal perforator . However, in 20% of our patients, coronary lesion was found in the middle part of the LAD. Similar findings have been stated in a few case reports, where occlusion was seen in the middle of the LAD rather than the proximal part .
It is interesting to note that these characteristic ECG findings of Wellen's criteria can also be seen in cases of pulmonary embolism, central nervous system injury or due to drug-induced effects .
In conclusion, these characteristic findings in precordial leads should not be over looked, even if there is no ST-deviation. Since this artery supplies the anterior myocardium, inability to recognize this specific ECG pattern can result in massive infarction of the anterior wall, substantial left ventricular dysfunction, and/or death. Most significantly, the classic ECG presentation of Wellens' syndrome may be imprecise during the acute phase of ischemia, and appear after chest pain has subsided when everybody proceeds at a slow and relaxed pace. Early intervention and revascularization strategies are recommended for patients with such ECG findings.