Author + information
- Received May 21, 1998
- Revision received August 5, 1998
- Accepted September 10, 1998
- Published online January 1, 1999.
- Jun-Ichi Suzuki, MDa,*,
- Ryoichi Shimamoto, MDa,
- Jun-Ichi Nishikawa, MD∗,
- Tadashi Yamazaki, MDa,
- Taeko Tsuji, MDa,
- Fumitaka Nakamura, MDa,
- Wee Soo Shin, MDa,
- Toshiaki Nakajima, MDa,
- Teruhiko Toyo-Oka, MDa and
- Kuni Ohotomo, MD∗
- ↵*Address for correspondence: Dr. Jun-ichi Suzuki, The Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 1138655, Japan
Objectives. A long-term follow-up study with nuclear magnetic resonance (NMR) imaging was undertaken to detect the morphological onset and to establish the early diagnosis in apical hypertrophic cardiomyopathy (HCM).
Background. A spadelike configuration on left ventriculogram (LVG) is regarded as a diagnostic criterion for the classical apical HCM. There also exists a segmented hypertrophy at the apical level without indicating the spadelike features (a nonspade configuration). To detect the hypertrophied myocardium of the nonspade configuration, circumferential scrutiny of the apex is required. Although both configurations can be underlying causes of giant negative T waves, etiological relationship between the two is not clarified.
Methods. The criteria for the spadelike configuration defined on left ventricular short-axis NMR images were as follows: (apical maximal thickness ≥15 mm), (apical anterior thickness over basal anterior thickness ≥1.3) and (apical posterior thickness over basal posterior thickness ≥1.3). Thirteen patients who had predominant hypertrophy (≥15 mm) at the apical level without the spadelike configuration underwent NMR imaging twice before and after 54 ± 10 months’ follow-up.
Results. Apical hypertrophy that had been confined to the lateral wall in four, the anterior-lateral wall in two, and the septal-anterior wall in one developed to become circumferential hypertrophy that fulfilled the criteria for the spadelike configuration after the follow-up period.
Conclusions. The spadelike configuration can begin with the nonspade configuration and therefore, both can constitute a single disease entity of apical HCM. The early diagnosis of apical HCM can be achieved by identifying the hypertrophy frequently confined to the lateral wall at the apical level.
In the course of progress of the clinical stage of hypertrophic cardiomyopathy (HCM) morphological features of the left ventricle may alter. Classical apical HCM is characterized by giant negative T waves (1)(Fig. 1)and a spadelike configuration (2). This configuration on left ventriculogram (LVG) in the right anterior oblique projection is delineated both by the hypertrophied myocardium at the apical anterior wall and by that at the apical posterior wall. In fact left ventricular short-axis nuclear magnetic resonance (NMR) images demonstrate that the apex of the spadelike configuration is hypertrophied circumferentially (Fig. 2)(3). As an additional underlying disorder of giant negative T waves, a subtype of HCM with apical predominance was identified by scrutinizing the apex on left ventricular short-axis NMR images (3). The distribution of the hypertrophied myocardium in this subtype is frequently proven to be confined to the apical lateral wall which LVG in the right anterior oblique projection cannot evaluate. Accordingly, LVG in this projection often indicates the normal left ventricular cavity (a nonspade configuration). Although the features on LVG between the two configurations are quite different (Fig. 2), both share the common clinical implication of causing giant negative T waves.
NMR imaging can circumferentially quantify the apex on the left ventricular short-axis images with high interstudy reproducibility (4–6). Therefore, to clarify whether or not the confined hypertrophy of the nonspade configuration developed to become circumferential hypertrophy of the spade-like configuration, and to study the timing of the transformation of the localized apical hypertrophy to diffuse apical hypertrophy, in other words, to identify the morphological onset of myocardial hypertrophy at the apex and to establish early diagnosis in the classical apical HCM, a long-term NMR follow-up study was undertaken.
NMR imaging was consecutively performed in patients who had chronic and progressive T wave inversions and who were clinically suspected of having the classical apical HCM. Thirty-three patients (Table 1)were assigned to the subtype of HCM with the nonspade configuration on the basis of the diagnostic criteria with NMR imaging described below. The second NMR examination with a mean follow-up period of 54 ± 10 months was performed in 13 patients randomly selected from the 33 patients with the nonspade configuration. Average age of the 13 patients was 54 ± 9 years and their mean negativity of the deepest negative T waves in the precordial leads was 8.6 ± 4.5 mm (1 mm = 0.1 mV).
NMR imaging and measurements
For image acquisition, Magnetom (Siemens Medical Systems, Erlangen, Germany) with a 1.5-T superconducting magnet was used. The imaging sequence was an electrocardiogram triggered spin-echo with an echo time of 34 ms or a k-space segmented cine NMR imaging (turboFLASH) with an echo time of 6.1 ms. All measurements were done on end-diastolic left ventricular short-axis NMR images at the basal level and at the apical level. The basal level was set at the level of the mitral chordae. The distance between the imaging plane for the apical level and the tip of the left ventricular apex was 2–3 cm. The maximal wall thickness was determined at the basal level and at the apical level. The wall thicknesses of the septum, the anterior wall, the lateral wall and the posterior wall were evaluated on NMR short-axis images at the basal level. Similarly the wall thicknesses of the septum, the anterior wall, the lateral wall and the posterior wall were measured on NMR short-axis images at the apical level (Fig. 2).
Definition of the spadelike configuration
In our previous study, the apical wall thickness in the normal subjects was 9 ± 2 mm (3). Accordingly, the wall thickness ≥15 mm (15 mm = mean + 3SD) was considered to indicate hypertrophic at the apical level. Moreover, (ratio of the maximal wall thickness on the left ventricular short-axis NMR image at the apical level to that at the basal level) ≥1.3 was tentatively considered to be apical predominance. According to the original description of the spadelike configuration, a silhouette of the left ventricular cavity resembling a “spade” in a deck of playing cards on LVG in the right anterior oblique projection was considered as the spadelike configuration (2). This configuration is the reflection of the hypertrophied myocardium at the apical anterior wall and the apical posterior wall on LVG in this projection. Therefore, both (ratio of the apical anterior wall thickness over the basal anterior wall thickness) ≥1.3 and (ratio of the apical posterior wall thickness over the basal posterior wall thickness) ≥1.3 were required for the diagnosis of the spadelike configuration. The cutoff value of 1.3 was tentatively used for the three abovementioned ratios.
Definition of the nonspade configuration
The patients with myocardial hypertrophy with apical predominance, i.e., with (the maximal wall thickness on the left ventricular short-axis NMR image at the apical level) ≥15 mm and (ratio of the maximal wall thickness on the left ventricular short-axis NMR image at the apical level to that at the basal level) ≥1.3, who did not fulfill the abovementioned criteria for the spadelike configuration were considered as apically predominant HCM with the nonspade configuration.
Thirteen patients who were diagnosed as HCM with apical predominance with the nonspade configuration on the first NMR imaging were randomly selected and underwent the second NMR examination with the follow-up period of 54 ± 10 months. The imaging planes of the second NMR examination coincided with those of the first NMR examination as exactly as possible.
All results were expressed as mean value ±1 S.D. Differences between the two groups were analyzed with an unpaired t-test. Significant differences were indicated by p < 0.05.
The pattern of distribution of the hypertrophied myocardium with wall thickness ≥15 mm at the apical level on the first and the second NMR short-axis images in 13 patients is summarized in Table 2. After the follow-up period, 7 patients with the nonspade configuration at the first NMR examination fulfilled the criteria for the spadelike configuration at the second NMR examination (group 1). The distribution pattern of hypertrophied myocardium on the first NMR short-axis images at apical level in group 1 was (apical lateral) in four patients (Fig. 3), (apical anterior-apical lateral) in two patients (Fig. 4), and (apical septum-apical anterior) in one patient. On the second NMR images, the localization of segments with wall thickness ≥15 mm was (apical septum-apical anterior-apical lateral-apical posterior, i.e., circumferential at the apical level) in six patients (Fig. 4), and (apical anterior-apical lateral-apical posterior) in one patient (Fig. 3).
On the other hand, as to the remaining six patients with the nonspade configuration (group 2) the pattern after the follow-up period showed no changes in four patients and indicated growth of hypertrophy, which was not enough to fulfill the criteria for the spadelike configuration in two patients (group 2). On the short-axis images at the apical level of the first NMR examination, the localization of the hypertrophied myocardium was confined to the apical lateral wall in three patients and to the apical anterior wall in three patients (Table 2).
The wall thickness of the left ventricle at the basal level and at the apical level measured at the first and the second NMR examination is summarized in Tables 3 and 4. ⇓⇓The thickness of the posterior wall at the apical level significantly increased in group 1 after the follow-up period, whereas in group 2, there was no significant change in the apical wall thickness of the posterior wall.
Comparison of clinical features between seven patients with transfiguration after the follow-up period (group 1) and six those without transfiguration (group 2) is summarized in Table 5. There was no difference in the follow-up period between the two. Although the negativity of the negative T waves of group 1 was significantly greater (p < 0.05), there was no difference in the ratio of the maximal wall thickness on the left ventricular short-axis NMR image at the apical level to that at the basal level on the first NMR examination.
In 1976, Sakamoto et al. reported asymmetrical apical hypertrophy with an increase of magnitude of myocardial hypertrophy toward the apex on M-mode echocardiography in patients with giant negative T waves (1). In 1979, Yamaguchi et al. described a configuration on end diastolic LVG in the right anterior oblique projection (2). The configuration was nicknamed “spadelike” because the left ventricular cavity in this projection resembled the “spade” in playing cards. This configuration became a diagnostic criterion for the classical apical HCM (7–16). In 1993, by scrutinizing the apex on left ventricular short-axis NMR images, a nonspade subtype was identified as a new underlying disorder for markedly inverted T waves whose hypertrophied myocardium was so narrowly confined to a small region at the apical level, for example, to the apical lateral wall, that LVG in the right anterior oblique projection did not indicate the spadelike configuration or did not demonstrate even the existence of the confined hypertrophy (3). It is not clarified whether the nonspade configuration and the spadelike configuration constitute the two independent disease entities or whether the former is the beginnings of the latter.
NMR imaging demonstrates that the distribution of the hypertrophied myocardium is circumferential at the apical level in patients with the spadelike configuration. In 7 patients from the current study, left ventricular short-axis NMR images revealed that the localization of hypertrophied myocardium confined to the apical lateral wall or to the apical anterior wall at the first NMR examination became almost circumferential after the follow-up period. This transfiguration of pattern of distribution of hypertrophy at the apical level was due to an increase in the wall thickness of the posterior wall at the apical level. Thus, the possible process of growth of myocardial hypertrophy from onset to the classical HCM with the spadelike configuration is not circumferentially homogeneous at the apical level but is segmented with starting from mainly lateral wall and expanding to the anterior wall and to the posterior wall at the apical level. Thus, the spadelike configuration begins with the nonspade configuration, or the nonspade subtype is not an independent disease entity but possibly is the early stage of the single disease entity of apical HCM. However it is noteworthy that even such a small amount of hypertrophy of the early stages of apical HCM with the nonspade configuration does cause giant negative T waves. The early diagnosis of apical HCM is achieved by identifying the small quantity of hypertrophied myocardium frequently confined to the lateral wall of the apex which can be detected only on the left ventricular short-axis images.
We thank Yoshio Yazaki, MD, Masao Omata, MD, Tsuguya Sakamoto, MD, and Tsuneaki Sugimoto, MD for their direction and advice.
- hypertrophic cardiomyopathy
- left ventriculography or left ventriculogram
- nuclear magnetic resonance
- Received May 21, 1998.
- Revision received August 5, 1998.
- Accepted September 10, 1998.
- American College of Cardiology
- Suzuki J-i,
- Watanabe F,
- Takenaka K,
- et al.
- Been M,
- Kean D,
- Smith M.A,
- Douglas R.H.B,
- Best J.J.K,
- Muir A.L
- Keren G,
- Belhassen B,
- Sherez J,
- et al.