Noninvasive testing in women presenting with chest pain: evidence for diagnostic uncertainty

OBJECTIVE

To gain insight into the diagnostic utility of exercise stress testing in women.

DESIGN

Observational prospective cohort study.

SETTING

The Victoria General Hospital, Halifax, Nova Scotia.

PARTICIPANTS

Consecutive women with chest pain referred by cardiologists or internists for exercise stress testing between May 30, 1992 and November 30, 1992 and followed prospectively to February 28, 1993.

INTERVENTION

The proportion of patients subsequently referred for thallium scintigraphy and/or coronary angiography and their clinical profiles were determined.

MAIN RESULTS

Of 183 patients studied, stress testing was positive in 48 (26.2%), negative in 48 (26.2%) and nondiagnostic in 87 (47.5%). Women with negative results were more likely to have had normal baseline electrocardiograms (ECGs) (P = 0.002) and least likely to have undergone prior angiography (P = 0.0003). Subsequent thallium scintigraphy and/or coronary angiography was undertaken in 33.3%, 18.8% and 27.6% with positive, negative and nondiagnostic index stress tests, respectively. None of chest pain, cardiac risk factors, previous cardiac investigations or baseline ECG discriminated 33 patients with negative or nondiagnostic stress results who had additional tests from 102 who did not.

CONCLUSION

Exercise stress testing poorly screens women with chest pain for coronary artery disease (diagnostic in only 52.5%). Further study was undertaken in 27.6% with nondiagnostic tests and, surprisingly, in 18.8% with negative results. Why certain women with nondiagnostic, and so many with negative, stress tests were referred for further investigation was unclear. These results suggest diagnostic uncertainty when females presenting with chest pain are assessed.

The relationship of mast cells and their secreted products to the volume of fibrosis in posttransplant hearts

A series of 96 posttransplant endomyocardial biopsies taken from 11 patients was subjected to quantitative analysis of mast cells and fibrosis. Ultrastructural analysis showed that mast cell numbers were increased and there was obvious degranulation in some posttransplant hearts. Activated mast cells and their secreted products, which contain heparin and histamine, are toxic to the hearts and may contribute to interstitial and perimyocytic fibrosis. The numbers of mast cells and granules were correlated with volume of fibrosis (r = 0.63, P less than 0.025; r = 0.73, P less than 0.01). There were differences between the release of mast cell granule contents seen in the posttransplant hearts and the rapid and massive reaction of anaphylactic degranulation of mast cells. Some mast cells progressively lost their dense granule contents, displaying a variety of piecemeal degranulation that indicates a slow degranulation process. These events occurred from the first week; they lasted from weeks to months. The fibrosis developed quickly in the cases with more mast cells and degranulation. The cases with fewer mast cells and granules showed only mild increases in the volume of fibrosis. Mast cells appeared as early as the first posttransplantation week. Patients with greater numbers of mast cells underwent more severe rejection episodes. This study demonstrated that mast cells play an early and important role in the perimyocytic and interstitial fibrosis of posttransplant hearts. Mast cells may also be important in the inflammatory process of rejection reaction. The severity of fibrosis appears related to the density of mast cells and their granules.

Effectiveness of a non-amalgamated ambulance service on out-of-hospital sudden cardiac death

Many Canadian communities rely on non-amalgamated ambulance services to respond to out-of-hospital sudden cardiac arrest victims. These pre-hospital care systems lack a central coordinating and dispatching facility, a publicized, easily-accessible telephone number (911) and vehicles equipped with monitor-defibrillators, and are generally staffed by personnel trained only in basic cardiac life support. To receive definitive care, the victim of a cardiac arrest in these communities must be successfully transported to a hospital. In the study area, 114 victims of out-of-hospital sudden death were identified in a community served by a non-amalgamated ambulance service over a 12-month period for an annual incidence rate of 6.1/10,000. The mean age was 64 +/- 11.5 years with the majority (78%) of arrests occurring in the home. The collapse to CPR time was 10.2 +/- 6.7 minutes and the ambulance response time was 5.2 +/- 3.9 minutes. The estimated time from collapse to the victims receiving definitive care was 36.4 +/- 19.1 minutes. Overall, only 8 victims (8.8%) survived and were discharged from hospital. Based on the data presented, survival rate for cardiac arrest victims treated by a non-amalgamated ambulance system are inferior to those reported for pre-hospital care services capable of providing advanced cardiac life support at the scene. Whether all of the components of an established paramedic program are required to improve survival rates in individual communities remains undetermined.

Non-Q-wave acute myocardial infarction: body surface potential map and ventriculographic patterns

Day 5 body surface map and radionuclide angiographic patterns were compared among 56 patients with first non-Q-wave or Q-wave acute myocardial infarction (AMI). Three radionuclide angiographic patterns were recognized in patients with non-Q infarction: no wall motion abnormalities (n = 8), single-segment wall motion abnormalities (n = 10) and multiple-segment wall motion abnormalities (n = 9). In contrast, only 2 radionuclide angiographic patterns were identified in patients with Q-wave infarction: multiple-segment wall motion abnormalities (n = 25) and single-segment wall motion abnormalities (n = 4). The Q-wave distributions of 14 of 18 patients with non-Q infarction with 0 or 1 wall motion abnormalities were normal; 2 patients had "missed" anterior; 1 patient had inferior; and 1 had posterior AMI patterns. Of 9 patients with non-Q infarction who had multiple-segment wall motion abnormalities, 8 had infarct Q waves on the posterior torso. Q-wave patterns in patients with anterior (n = 17) and inferior (n = 12) Q-wave infarctions were typical and homogeneous for each group. Quantitative analysis of minimum Q-zone integral, sigma Q-wave integrals, ST-integral maximum, wall motion abnormality score and ejection fraction revealed no differences between patients with non-Q-wave and those with inferior Q-wave infarction. In contrast, patients with anterior AMI had significantly more abnormal values of all variables than either of the other groups. Overall, the data support the concept of non-Q-wave AMI as a distinct, if heterogeneous, pathophysiologic entity.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiographic and ventriculographic recovery patterns in Q wave myocardial infarction

To further define the capacity for recovery after acute phase electrical and mechanical injury in patients with Q wave myocardial infarction who were treated with standard measures, 120 lead body surface potential maps and radionuclide angiograms were recorded at day 5 before discharge and month 6 after infarction in 23 patients with a first infarction (12 anterior and 11 inferior by standard 12 lead electrocardiographic criteria). In addition to assessment of spatial changes in electrocardiographic and wall motion patterns, five quantitative variables were evaluated: minimal Q zone integral, sigma Q wave integral, maximal ST integral, left ventricular ejection fraction and left ventricular wall motion abnormality score. From day 5 to month 6 after infarction, the only change in the inferior infarction group was a gain in sigma Q wave (-91 +/- 40 mu V X s X 10(2) to -68 +/- 24 mu V X s X 10(2); p less than 0.05). In contrast, all variables improved over the same time period in the anterior infarction group: Q zone minimum, -34 +/- 20 to -24 +/- 13 mu V X s (p less than 0.05); sigma Q wave, -160 +/- 122 X 10(2) to -120 +/- 90 mu V X s X 10(2) (p less than 0.05); ST maximum, 44 +/- 19 to 18 +/- 9 mu V X s (p less than 0.01); ejection fraction, 54 +/- 7 to 63 +/- 17% (p less than 0.05); and wall motion score, 6 +/- 3 to 3 +/- 3 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Q-wave infarction: pathophysiology of body surface potential map and ventriculographic patterns in anterior and inferior groups

To define and relate the body surface electrocardiographic and left ventricular wall motion patterns in the acute phase of Q-wave infarction, we recorded 120-lead body surface potential maps and radionuclear angiograms in 29 patients on the fifth day of their first infarction. By standard 12-lead electrocardiographic criteria, 17 patients were designated as anterior infarction and 12 as inferior infarction. Body surface map infarct patterns in the anterior group were characterized primarily by abnormal Q-wave, negative Q-zone and positive ST-segment integral patterns over the anterior torso and little reciprocal change. The maps of the inferior patient group were characterized primarily by depolarization and repolarization infarct patterns over the inferior torso and marked reciprocal changes in all integral patterns over the anterior torso. Both groups displayed infarct patterns over a common area of the right anterior-inferior torso. In the anterior group depolarization minima and repolarization maxima were clustered in a small precordial area; in the inferior group the same extrema were widely scattered over the inferior torso, both anteriorly and posteriorly. Segmental left ventricular wall motion analysis revealed that the 3 most commonly and most severely involved segments were the same in both infarct groups--apical, infero-apical and antero-lateral. Basal septum and antero-basal segmental dysfunction were exclusive to the anterior group; postero-lateral and infero-basal involvement, to the inferior group.(ABSTRACT TRUNCATED AT 250 WORDS)

Indirect measurement of infarct size. Correlative variability of enzyme, radionuclear angiographic, and body-surface-map variables in 34 patients during the acute phase of first myocardial infarction

To gain a correlative perspective of indirect indications of the size of a myocardial infarct, we measured several body-surface electrocardiographic variables and several enzyme and radionuclear angiographic indicators of an infarct's size in 34 patients during the acute phase of first infarction. We found that bivariate correlations ranged widely, from an r value of 0.05 to an r value of 0.92, but were significantly (p less than 0.001) higher when variables from the same technique were correlated (mean r, 0.60 +/- 0.27), as opposed to correlations of variables from different techniques (mean r, 0.27 +/- 0.18). Trivariate comparisons among techniques produced significantly (p less than 0.001) higher r values, but the highest, an r value of 0.76 (total wall motion abnormality score; peak lactic dehydrogenase level; ST-segment integral maximum), indicated that even in this best case, only about 60 percent of the variation of one variable was dependent on or due to the two other variables. These data demonstrate that multiple indirect quantitative indicators of myocardial injury can vary widely in their correlations within the same population of infarcts, and much remains unknown in their relationships during the acute phase. Caution should be exercised, therefore, in their clinical application to predict an infarct's size in individual patients with acute myocardial infarction.

Temporal evolution of body surface map patterns following acute inferior myocardial infarction

We studied the evolution of body-surface potential map (BSPM) patterns in 32 patients following first acute inferior myocardial infarction. Initial BSPMs were obtained at a mean of 79 hours post-infarction; follow-up BSPMs, a mean of eight months post-infarction. Temporal area-of-difference maps, constructed by subtracting initial from follow-up group-mean BSPMs, revealed reciprocal changes over the superior and inferior torso for both Q-zone and ST-segment time-integral distributions. The temporal changes in Q-zone patterns were small but definite: over the inferior torso there was a relative gain in Q-zone values and, over the superior torso, a relative decrease. In contrast, there were marked spatial and quantitative changes of ST-segment distributions during the follow-up period. Over the superior torso, particularly anteriorly, there was a gain in ST-segment values; over the inferior torso, a decrease. With the small temporal changes in Q-zone time-integral distributions, individual Q-zone maps continued to reflect a pattern of inferior myocardial infarction at follow-up. In contrast, the marked temporal changes in ST-segment time-integral distributions resulted in individual map patterns at follow-up that were nearly indistinguishable from normal ST-segment maps. The relatively small changes in depolarization time-integral patterns during the early post-infarction period suggest that the Q-zone patterns of the acute phase of myocardial infarction reflect near-irreversible or completed myocardial damage. The marked normalization of repolarization time-integral patterns during the recovery phase suggests, however, that there are also considerable areas of myocardium-at-risk during the early phase of the infarction process which stabilize with time.