Abstract
Background:
Several reports have recently described the variant form of takotsubo cardiomyopathy exhibiting midventricular ballooning. The purpose of this study was to assess electrocardiographic (ECG) findings on admission in patients with midventricular ballooning.
Hypothesis:
ECG findings are different between the midventricular ballooning form and apical ballooning form of takotsubo cardiomyopathy.
Methods:
We reviewed ECGs on admission in 6 patients with midventricular ballooning and 20 patients with apical ballooning. The sum of ST segment elevation in leads V1 to V3 or in leads V4 to V6 was obtained. The number of leads showing ST segment elevation and/or T wave inversion was also obtained. These ECG findings were compared between the 2 groups.
Results:
In midventricular ballooning, ECG changes including ST segment elevation and/or T wave inversion were observed frequently in leads V2 and V3, and were not observed in leads II, III, −aVR, aVF, V5, and V6. On the other hand, in apical ballooning, they were found in all leads. They were most common in leads V4 and V5. The sum of ST segment elevation in leads V1 to V3 was similar (2.6 ± 2.0 mm vs 2.7 ± 2.0 mm, P = not significant), and the sum of ST segment elevation in leads V4 to V6 was significantly lower in midventricular ballooning than apical ballooning (0.4 ± 0.8 mm vs 3.5 ± 3.0 mm, P<0.05). The number of leads showing ST segment elevation and/or T wave inversion was significantly lower in midventricular ballooning than apical ballooning (3.2 ± 1.0 leads vs 6.3 ± 2.2 leads, P<0.01).
Conclusions:
Our data suggested that midventricular ballooning may show limited ECG changes despite broad wall motion abnormality. © 2011 Wiley Periodicals, Inc.
The authors have no funding, financial relationships, or conflicts of interest to disclose.
Introduction
A novel cardiac syndrome exhibiting transient left ventricular apical wall motion abnormality (apical ballooning) with chest symptoms and electrocardiographic (ECG) changes has become accepted worldwide as a distinct clinical entity.1, 2, 3, 4, 5, 6, 7, 8 This disorder has been widely called takotsubo cardiomyopathy. Several reports have recently described its variant form exhibiting midventricular ballooning.9, 10, 11 In patients with apical ballooning, ECG usually shows ST segment elevation and subsequent T wave inversion with QT interval prolongation during the early stage. However, there is little information about ECG findings in patients with midventricular ballooning. To address this issue, we reviewed ECGs on admission in patients with midventricular ballooning and those with apical ballooning and compared ECG findings between the 2 groups.
Methods
Study Population
This study consisted of 26 patients with takotsubo cardiomyopathy who underwent cardiac catheterization within 24 hours after the onset. Takotsubo cardiomyopathy was diagnosed by acute and transient left ventricular ballooning extending beyond 1 coronary artery region.2, 3 The midventricular ballooning form was characterized by akinesia of the middle portion of the left ventricular chamber, with normokinesia of the apical and basal portions. The apical ballooning form was characterized by akinesia of the mid‐to‐distal portion of the left ventricular chamber, with normokinesia of the basal portion. These wall motion abnormalities were followed by transthoracic echocardiography. Heart failure was defined by the presence of symptoms and signs of pulmonary congestion. Patients with idiopathic cardiomyopathy, pheochromocytoma, or prior myocardial infarction were excluded in this study.
Cardiac Catheterization
Coronary angiography and left ventriculography were performed after administration of heparin. A left ventriculogram was obtained in the 30‐degree right anterior oblique projection. Written informed consent was obtained from all patients and/or their families before the procedure.
Electrocardiogram
A 12‐lead ECG was recorded on admission at a paper speed of 25 mm/sec and an amplification of 10 mm/mV. The isoelectric line was defined as the level of the preceding TP segment. ST segment deviation was measured to the nearest 0.5 mm, 80 msec after the J point. A ST segment elevation was considered present if ST segment elevation was ≥0.5 mm in the limb leads, and ST segment elevation was ≥1.0 mm in the precordial leads. The sum of ST segment elevation in leads V1 to V3 or in leads V4 to V6 was obtained as previously reported.8 A T wave inversion was considered present if the depth was >1.0 mm in any lead.12 The number of leads showing ST segment elevation and/or T wave inversion was obtained in a blinded manner by the 2 experienced cardiologists (S.K. and K.N.).
Statistical Analysis
Statistical analysis was performed with χ 2 and Student t tests. Differences were considered significant if the P value was <0.05. All data are expressed as mean ± standard deviation.
Results
Patient Characteristics
There were 6 patients with midventricular ballooning form and 20 patients with the apical ballooning form of takotsubo cardiomyopathy. Left ventriculograms of representative cases are shown in Figure 1, and clinical characteristics are shown in Table 1. There was no significant difference in age, gender, hypertension, diabetes, prior stressor, medications, systolic blood pressure, heart rate, C‐reactive protein or creatine kinase‐MB, or left ventricular ejection fraction between the 2 groups. Incidence of heart failure was similar between the 2 groups (33% vs 25%, P = not significant). Three patients with apical ballooning died of their underlying disease. No patient died of complications of takotsubo cardiomyopathy. Incidence of in‐hospital death was also similar between the 2 groups (0% vs 15%, P = not significant).
Figure 1.
Left ventriculograms of representative cases of midventricular ballooning (left panels) and apical ballooning (right panels). The midventricular ballooning form is characterized by akinesia of the middle portion of the left ventricular chamber, with normokinesia of the apical and basal portions. The apical ballooning form is characterized by akinesia of the mid‐to‐distal portion of the left ventricular chamber, with normokinesia of the basal portion.
Table 1.
Patient Characteristics
| Midventricular Ballooning (n = 6) | Apical Ballooning (n = 20) | P Value | |
|---|---|---|---|
| Age (y) | 65 ± 16 | 71 ± 11 | NS |
| Male | 1 (17%) | 2 (10%) | NS |
| Hypertension | 3 (50%) | 4 (20%) | NS |
| Diabetes | 0 (0%) | 2 (10%) | NS |
| Prior emotional or physical stressor | 6 (100%) | 18 (90%) | NS |
| Medications | |||
| Angiotensin‐converting enzyme inhibitors | 0 (0%) | 1 (5%) | NS |
| Angiotensin receptor blockers | 2 (33%) | 2 (10%) | NS |
| β‐blockers | 0 (0%) | 1 (5%) | NS |
| Calcium channel blockers | 2 (33%) | 3 (15%) | NS |
| Nitrates | 1 (17%) | 3 (15%) | NS |
| Statins | 0 (0%) | 4 (20%) | NS |
| Systolic blood pressure (mm Hg) | 112 ± 12 | 125 ± 30 | NS |
| Heart rate (bpm) | 93 ± 36 | 97 ± 20 | NS |
| C‐reactive protein (mg/dL) | 0.39 ± 0.72 | 1.60 ± 2.29 | NS |
| Creatine kinase‐MB (IU/L) | 27 ± 20 | 23 ± 9 | NS |
| Left ventricular ejection fraction (%) | 48 ± 5 | 42 ± 8 | NS |
Abbreviation: NS, not significant.
Electrocardiographic Findings
ECGs of representative cases are shown in Figure 2, and the incidence of ST segment elevation and/or T wave inversion is shown in Figure 3. In midventricular ballooning, they were observed frequently in leads V2 and V3, and were not observed in leads II, III, ‐aVR, aVF, V5, and V6. On the other hand, in apical ballooning, they were found in all leads. They were most common in leads V4 and V5. ECG findings are shown in Table 2. There was no significant difference in the sum of ST segment elevation in leads V1 to V3 between midventricular ballooning and apical ballooning (2.6 ± 2.0 mm vs 2.7 ± 2.0 mm, P = not significant). The sum of ST segment elevation in leads V4 to V6 was significantly lower in midventricular ballooning than apical ballooning (0.4 ± 0.8 mm vs 3.5 ± 3.0 mm, P<0.05). The number of leads showing ST segment elevation and/or T wave inversion was significantly lower in midventricular ballooning than apical ballooning (3.2 ± 1.0 leads vs 6.3 ± 2.2 leads, P<0.01). There was no significant difference in QT interval between midventricular ballooning and apical ballooning (348 ± 27 msec vs 349 ± 47 msec, P = not significant).
Figure 2.
Electrocardiograms of representative cases of midventricular ballooning (left panels) and apical ballooning (right panels). In the case of midventricular ballooning, ST segment elevation was found in leads V2 to V3. In the case of apical ballooning, it was found in leads I, II, III, −aVR, aVF, and V2 to V6.
Figure 3.
Incidence of electrocardiographic changes in each lead in midventricular ballooning (black bars) and apical ballooning (white bars). (A) This panel shows the incidence of ST segment elevation. (B) This panel shows the incidence of T wave inversion. (C) This panel shows the incidence of ST segment elevation and/or T wave inversion. In midventricular ballooning, they were observed frequently in leads V2 and V3. On the other hand, in apical ballooning, they were most common in leads V4 and V5. *P<0.05. **P<0.01.
Table 2.
Comparison of Electrocardiographic Findings
| Midventricular Ballooning (n = 6) | Apical Ballooning (n = 20) | P Value | |
|---|---|---|---|
| Sum of ST segment elevation in leads V1–V3 (mm) | 2.6 ± 2.0 | 2.7 ± 2.0 | NS |
| Sum of ST segment elevation in leads V4–V6 (mm) | 0.4 ± 0.8 | 3.5 ± 3.0 | <0.05 |
| No. of leads showing ST segment elevation | 2.5 ± 1.6 | 5.1 ± 3.0 | NS |
| No. of leads showing T wave inversion | 1.0 ± 1.5 | 2.9 ± 2.7 | NS |
| No. of leads showing ST segment elevation and/or T wave inversion | 3.2 ± 1.0 | 6.3 ± 2.2 | <0.01 |
| QT interval (msec) | 348 ± 27 | 349 ± 47 | NS |
Abbreviation: NS, not significant.
Discussion
Present Study
In this study we demonstrated that ECG changes in midventricular ballooning were observed frequently in leads V2 and V3, and that midventricular ballooning form showed limited ECG changes despite broad wall motion abnormality.
Previous Studies
Takotsubo cardiomyopathy is characterized by left ventricular apical wall motion abnormality with chest symptom, ECG, and minimal myocardial enzymatic release. These characteristics mimic those of acute myocardial infarction (AMI), and it is required to differentiate takotsubo cardiomyopathy from AMI during the early stage. ECG is a routine examination in patients with chest pain, and several reports have shown its usefulness in differentiating takotsubo cardiomyopathy from AMI.4, 8, Ogura et al previously assessed ECGs in patients with the apical ballooning form of takotsubo cardiomyopathy and anterior AMI, and showed that the ratio of ST segment elevation in leads V4–V6 to V1–V3 was significantly higher in patients with takotsubo cardiomyopathy compared to those with anterior AMI.8 In this study, ECG changes were found mainly in leads V4 to V5 in patients with the apical ballooning form of takotsubo cardiomyopathy, and our results were consistent with those of their study. Apical aneurysm formation results from takotsubo cardiomyopathy as well as myocardial infarction or hypertrophy cardiomyopathy. Although the pathophysiologic etiology is different among these disorders, ST segment elevation in leads V4 to V5 is often found commonly in patients with apical aneurysm formation. Thus, leads V4 to V5 seem to reflect the distal portion of the left ventricular chamber (apical leads), and ECG changes in apical leads are useful in diagnosing the apical ballooning form of takotsubo cardiomyopathy.
ECG Findings in Midventricular Apical Ballooning
Several reports have recently demonstrated a variant form of takotsubo cardiomyopathy exhibiting midventricular ballooning with intact apical wall motion. Because the midventricular ballooning form is rare compared to the apical ballooning form of takotsubo cardiomyopathy, there is little information about its ECG findings. Steen et al reported a case of midventricular ballooning in which initial ECG was unspecific.9 Hurst et al reported 4 cases of this form, and initial ECG showed normal or nonspecific T wave change in 2 cases.10 Ikeda et al also reported 2 cases in which initial ECG showed only T wave inversion in leads V1 to V3.11 In this study, ECG changes including ST segment elevation and/or T wave inversion were found mainly in leads V2 to V3, and were never found in lead V5 in midventricular ballooning. According to previous reports and our results, apical wall motion is intact in midventricular ballooning, and ECG changes are rare in leads V4 to V5, which reflect the distal portion of the left ventricular chamber. In our study, the incidence of ECG changes in limb leads was also low in midventricular ballooning compared to apical ballooning. The midventricular ballooning form seems to show limited ECG changes despite broad wall motion abnormality compared to the apical ballooning form of takotsubo cardiomyopathy. In addition, ST segment elevation and/or T wave inversion in leads V2 to V3 are often found as normal variants such as early repolarization. Because of these reasons, midventricular ballooning might be diagnosed at a later stage or overlooked. Clinicians should recognize that there is a possibility of the development of takotsubo cardiomyopathy with limited ECG changes.
Study Limitations
There are several limitations in this study. First, the number of patients with midventricular ballooning was low because this form was rare compared to the apical ballooning form. Second, we assessed only initial ECG changes, and did not assess serial ECG changes partly because some patients were discharged during the early stage.
Conclusion
Midventricular ballooning shows limited ECG changes despite broad wall motion abnormality. It might be difficult to obtain early and precise diagnosis of midventricular ballooning by using ECG.
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