Left Anterior Descending Artery Involvement Research Articles

Reevaluation of an Old Electrocardiographic Criterion for Coronary Disease: TV1 > TV6

Background:Two different studies were conducted to evaluate the value of T wave in V1 taller than T wave in V6 (TV1 > TV6) pattern as an indicator of coronary artery disease. Method: In the first study 5,300 resting ECGs were examined and the criterion was found in 283 patients. All of these patients were examined with echocardiography. In the second study, ECG tracings and coronary angiograms of another 500 patients were evaluated. Results:In the first study, in 59 of 283 patients left ventricular hypertrophy was detected and these patients were excluded from the study. There were ST segment‐T wave changes and/or Q wave on ECG suggesting coronary ischemia or myocardial infarction in 160 of the 224 patients. TV1, > TV6 criterion was the sole finding in 64 of the 224 patients. All of the 224 patients underwent coronary angiography and coronary artery disease was detected in 185 patients; 134 of the 160 patients (83.3%) and 51 of 64 patients (80%) had one‐vessel or multivessel disease. There was no significant difference among the groups regarding coronary artery disease. Left anterior descending artery was involved in all of the 185 patients. In the second study, 408 patients were found to have coronary disease involvement and 92 patients showed normal or insignificant coronary disease. Sixty‐six of the 408 patients with coronary disease and four of 92 patients were found to have the TV1 > TV6 pattern. Sensitivity of the criterion was 16.1%, specificity was 95.6%, and accuracy was 94.2%. Conclusions: According to these results, it is concluded that TV1 > TV6 with or without other ECG findings is a good criterion suggesting coronary artery disease, especially left anterior descending artery involvement in patients without left ventricular hypertrophy. A.N.E. 1999;4(4):397–400

Chronotropic response to exercise predicts angiographic severity in patients with suspected or stable coronary artery disease

Inappropriate chronotropic response to exercise has been observed to correlate with poor prognosis in patients with coronary disease, but the mechanism for this association is not well defined. We attempted to examine the association between chronotropic response to exercise and angiographic severity of coronary disease in patients with suspected or stable coronary artery disease. The chronotropic response, expressed as peak heart rate, chronotropic index (ratio of heart rate reserve and metabolic reserve utilized), or percent maximal heart rate achieved, was correlated with angiographic findings obtained within 180 days of the test. Significant coronary disease was defined as ≥1 stenosis of ≥50% in a major epicardial artery or its main branches; severe coronary disease was defined as ≥50% stenosis in all 3 epicardial arteries, or in the left main coronary trunk, or 2-vessel disease with ≥70% proximal left anterior descending artery stenosis. We observed that peak heart rate and percent maximal heart rate achieved were independent negative predictors of both significant and severe coronary disease by logistic regression. The chronotropic index predicted severe coronary disease only. All 3 parameters of chronotropic response exhibited a significant gradient of abnormality across the spectrum of coronary disease (p < 0.01 for all), expressed by the number of vessels involved and correlated with left anterior descending artery involvement (p < 0.05 for all). We conclude that chronotropic response to exercise predicts the presence and angiographic severity of coronary disease. This association is likely related to the proportion of left ventricular myocardium rendered ischemic during stress.

Bypass Surgery for Chronic Stable Angina: Predictors of Survival Benefit and Strategy for Patient Selection

The variable mortality risk associated with chronic stable angina calls for careful selection of patients for coronary artery bypass grafting (CABG) if the aim of management is to prolong life. The randomized and observational studies done in the last 20 years have identified the variables relevant to patient selection and thus have provided a rational basis for such clinical decisions. These studies showed that the sicker the patient, as gauged by relevant measures of coronary disease and cardiovascular morbidity, the more likely it is that CABG will prolong life. A CABG-related improvement in survival is therefore more likely to occur the worse the left ventricular function; the greater the number of diseased vessels; the more proximal the location of coronary lesions (more muscle is threatened by such lesions); the greater the severity of the lesions as determined by angiography; the more severe the angina; the more easily provocable the ischemia or the more extreme the measures of ischemia; and, within limits, the older the patient. Greater survival gain after CABG also occurs in patients with peripheral vascular disease, in patients with baseline electrocardiographic ST-segment and T-wave changes, and probably in women. Thus, patients are likely to live longer after CABG if they have left main disease; three-vessel disease with left ventricular dysfunction (ejection fraction less than 50%), class III or IV angina, provocable ischemia, or disease in the proximal left anterior descending coronary artery; two-vessel disease with proximal left anterior descending artery involvement; and two-vessel disease with class III or IV angina as well as either severe left ventricular dysfunction alone or moderate left ventricular dysfunction together with at least one proximal lesion. When the decision of whether to do CABG is less clear-cut, the presence of peripheral vascular disease, female sex, baseline electrocardiographic ST-segment and T-wave changes, or older age (over 60 but under 80 years) should weigh in favor of doing CABG. In general, patients with single-vessel disease do not seem to derive survival benefit from CABG.

Quantitative exercise thallium-201 single photon emission computed tomography for the enhanced diagnosis of ischemic heart disease

The clinical utility of exercise thallium-201 single photon emission computed tomography was investigated in 360 consecutive patients who had concomitant coronary arteriography. Tomographic images were assessed visually and from computer-quantified polar maps. Sensitivity for detecting coronary artery disease was comparably high using quantitative and visual analysis, although specificity tended to improve using the former method (87% versus 76%, p = 0.09). Quantitative analysis was superior to the visual method for identifying left anterior descending (81% versus 68%, p less than 0.05) and circumflex coronary artery (77% versus 60%, p less than 0.05) stenoses and detected most patients (92%) with multivessel coronary artery disease. Multivessel involvement was correctly predicted in 65% of the patients with more than one critically stenosed vessel. Exercise variables in patients with significant coronary artery disease were similar whether the tomographic images were normal or abnormal. However, patients with coronary stenoses and normal versus abnormal tomograms had a trend toward more single vessel disease (79% versus 62%, p = 0.07) and moderate coronary stenosis (66% versus 28%, p less than 0.001), but had less proximal left anterior descending artery involvement (8% versus 34%, p = 0.05). Computer-quantified perfusion defect size was directly related to the extent of coronary artery disease. Intra- and interobserver agreement for quantifying defects were excellent (r = 0.98 and 0.97, respectively). In conclusion, quantitative thallium-201 tomography offers improved detection of coronary artery disease, localization of the anatomic site of coronary stenosis, prediction of multivessel involvement and accurate determination of perfusion defect size, while maintaining a high specificity. Quantification of perfusion defects with single photon tomography may become important for assessing the effects of coronary reperfusion and prognostically stratifying patients with coronary artery disease.

Left ventricular responses to supine bicycle exercise assessed by radionuclide angiocardiography and a Swan-Ganz catheter.

Left ventricular responses to supine bicycle ergometer exercise were studied by gated radionuclide angiocardiography (RNA), in 12 normal subjects (group A), 11 coronary patients without effort angina (group B) and 17 coronary patients with effort angina (group C). In the serial measurement of global ejection fraction (EF) there was a significant increase during peak exercise (PEx) in group A and B. In group C, global EF during mild exercise (MEx) did not increase, but decreased significantly during PEx. These results suggest the necessity of achieving adequate exercise loading in the diagnosis of exercise-induced ischemia, and also, that the serial measurement of global EF during exercise appears to be highly valuable. In the assessment of regional wall motion on the basis of regional EF, abnormal responses to exercise were highly inducible in the anteroseptal region in coronary patients with left anterior descending artery involvement. Abnormal wall motion in the other regions was less indicative for right coronary or left circumflex artery dysfunction. We examined hemodynamic responses to exercise by a Swan-Ganz catheter during RNA study in 5 patients of group A, 5 of group B, and 9 of group C. There was a large increase in left ventricular stroke work index (LVSWI) with a small rise in pulmonary capillary wedge pressure (PCWP) in group A. In group B LVSWI increased with a moderate rise in PCWP during PEx. In group C there was a negligible increase of LVSWI despite a marked rise in PCWP. A similar relationship was present between the LVSWI and the end-diastolic count (EDC) in the left ventricular region of interest. In MEx, however, the rise in PCWP in group C was more prominent than the increase in EDC. Thus, the present data indicate that the left ventricle in group C operates on a steeper portion of the diastolic pressure-volume curve than that in group A or B.