ORIGINAL ARTICLE
Delayed Enhancement Magnetic Resonance Imaging in Hypertrophic Cardiomyopathy With Basal Septal Hypertrophy and Preserved Ejection Fraction: Relationship with Ventricular Tachyarrhythmia Yasuo Amano, MD,* Mitsunobu Kitamura, MD,† Masaki Tachi, MD,* Minako Takeda, MD,* Kyoichi Mizuno, MD,† and Shinichiro Kumita, MD* Objective: This study aimed to determine the relationship between delayed enhancement magnetic resonance imaging (DE MRI) and ventricular tachyarrhythmia in patients with hypertrophic cardiomyopathy (HCM) with basal septal hypertrophy and preserved ejection fraction (EF). Methods: One hundred seven patients with HCM with basal septal hypertrophy and EF greater than 50% underwent cine and DE MRI. Myocardial scar was identified with DE MRI. We assessed whether , patient s background, cine MRI findings, presence of myocardial scar, or number of scarred myocardial segments was related to the occurrence of ventricular tachyarrhythmia. Results: Patient,s age, family history of HCM, and number of scarred segments differed between the patients with and without the arrhythmia. A family history of HCM and number of scarred segments were significantly related to ventricular tachyarrhythmia (P < 0.01). Conclusions: The number of scarred segments is the significant DE MRI parameter related to ventricular tachyarrhythmia in HCM with basal septal hypertrophy and preserved EF. Key Words: hypertrophic cardiomyopathy, magnetic resonance imaging, delayed enhancement, myocardial scar, ventricular tachyarrhythmia (J Comput Assist Tomogr 2014;38: 67–71)
H
ypertrophic cardiomyopathy (HCM) is one of the leading causes of ventricular tachyarrhythmia and consequent sudden death.1–4 Myocardial scar or replacement fibrosis is related to ventricular tachyarrhythmia in HCM.5 Delayed enhancement magnetic resonance imaging (DE MRI) is useful for noninvasive detection of the myocardial scar related to regional hypertrophy and systolic function as well as that related to ventricular tachyarrhythmia.6,15 Delayed enhancement magnetic resonance imaging is expected to resolve clinical decision making, when risk stratification of HCM or indication for implantable cardioverter defibrillator (ICD) is inconclusive after assessing traditional risk markers HCM (eg, family history of sudden cardiac death and ventricular tachyarrhythmia) in each patient.4 In previous studies using DE MRI, the presence of myocardial scar, the number of scarred myocardial segments, the scar mass, or the scar percent have variously been reported to be predictors of arrhythmia.6,9,15 Conversely, Maron et al16 do not support a close relationship between the risk of ventricular
tachycardia (VT) and myocardial scar on DE MRI in a sizable population with HCM. These discrepancies may have arisen from the inclusion of various types of HCM. When end-stage HCM showing the dilated left ventricular (LV) cavity, lower ejection fraction (EF), or extensive scar is included, the frequency of ventricular tachyarrhythmia may increase.16,17 Moreover, the methodology of assessment of myocardial scar, irrespective of its relation to ventricular tachyarrhythmia, have varied in the previous studies.6,11,13,15,18,19 In the present study, we focused on HCM with basal septal hypertrophy and preserved EF (ie, >50%), the most common type of HCM encountered in clinical practice. The purpose of this study was to examine whether the presence of scar, extent of scarred myocardial segments, or other MRI findings were related to ventricular tachyarrhythmia in the HCM.
MATERIALS AND METHODS Patients From June 2006 to February 2013, consecutive 144 patients with a diagnosis of HCM underwent contrast-enhanced MRI. The diagnosis of HCM was based on echocardiography and MRI demonstration of LV myocardial hypertrophy greater than or equal to 15 mm and a nondilated LV cavity in the absence of other myocardial diseases, possibly producing LV hypertrophy. Basal septal hypertrophy was defined as the maximum basal septal thickness greater than or equal to 15 mm with a ratio between the anteroseptal and posterior wall thicknesses greater than 1.3 on cine steady-state free precession MRI at end-diastole.20,21 The indications for MRI examinations were the imaging diagnosis of HCM, measurement of myocardial thickness, myocardial mass, and cardiac function, identification of myocardial scar, or imaging study before alcohol septal ablation. The 25 patients with apical HCM, 6 with midventricular HCM, and 6 with impaired EF less than or equal to 50% were excluded from the study. Consequently, the 107 HCM patients were enrolled in this study, and comprised 37 men and 70 women, aged 17 to 86 years (65.4 [12.8] years). All patients gave their informed consent for participating MRI study, and the Institutional Ethics Committee approved this investigation.
Ventricular Tachyarrhythmia From the Departments of *Radiology, and †Cardiology, Nippon Medical School, Tokyo, Japan. Received for publication April 19, 2013; accepted June 29, 2013. Reprints: Yasuo Amano, MD, Department of Radiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan (e-mail: [email protected]). All authors declared no conflict of interests related to this article. Copyright © 2014 by Lippincott Williams & Wilkins
Ventricular tachyarrhythmia before MRI studies were noted based on the medical reports. The ventricular tachyarrhythmia included VT (ie, sustained VT, non-sustained VT of greater than or equal to 3 beats at 120 beats per minute, and repeated nonsustained VT) or ventricular fibrillation observed with electrocardiography (ECG) or Holter ECG in the patients with clinical symptoms.1,4,10,22
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67
J Comput Assist Tomogr • Volume 38, Number 1, January/February 2014
Amano et al
RESULTS
Magnetic Resonance Imaging Magnetic resonance imaging examinations were performed with a 1.5-T (n = 59) or 3.0-T scanner (n = 48) with a 5- or 6channel cardiac phased-array coil (Philips Healthcare, Best, the Netherlands). All cardiac images were gated to vector ECG and were obtained during multiple breath-holding. Two-dimensional cine steady-state free precession and DE images encompassing the entire LV myocardium were acquired in the short-axis view. Two-chamber long-axis views were also acquired with 2dimensional cine and DE imaging. The DE MRI was acquired using an inversion-recovery segmented T1-weighted gradientecho imaging sequence 10 minutes after a gadolinium injection at a dose of 0.15 mmol/kg (Gd-DTPA, Gd-DTPA-BMA, or Gd-DOTA). The myocardial signal was nullified based on LookLocker T1-scout imaging in each patient.23 The typical imaging parameters for the cine and DE MRI are shown in Table 1.
Analysis The maximum wall thickness at end-diastole, EF, and myocardial mass of the left ventricle were measured using short-axis cine imaging. A dedicated workstation was used for these analyses (ViewForum, Philips). Either a reader with 16-year experience in cardiac MRI or the other with 3-year experience analyzed cine imaging in the clinical routine. Myocardial scar was also visually identified if it was seen in greater than or equal to 2 slices and had bright signal by each reader. Thereafter, the scar was confirmed when its mean signal intensity of scar was greater than the mean signal intensity plus 6 standard deviation (SD) of the reference myocardium in each slice on the DE MRI.10,19 Continuous variables were expressed as means (SD). Categorical data were presented as patient numbers. The presence of a family history of HCM and myocardial scar were compared between patients with and without tachyarrhythmia. The patient's age, and maximum wall thickness, EF, and myocardial mass of the left ventricle, and number of American Heart Association segments with myocardial scar were also compared. Fisher exact test or an unpaired t test was used for comparison. We calculated positive and negative predictive values (PPV and NPV) of the number of scarred segments for the ventricular tachyarrhythmia. For the clinical or MRI variables with the statistical significance, a multivariate analysis with forward selection method was used to assess association between the variables and the occurrence of ventricular tachyarrhythmia. A P < 0.05 was defined as statistically significant. The odds ratios were calculated for the selected categorical data.
Among 107 HCM patients with basal septal hypertrophy and preserved EF, a family history of HCM was found in 22 (20.1%) patients. Fourteen (13.1%) patients presented with ventricular tachyarrhythmia. The patients with ventricular tachyarrhythmia were significantly younger (P = 0.01) and had family history of HCM more frequently (P < 0.01) than those without the arrhythmia. Fifty-nine (53.2%) of the 107 HCM patients with basal septal hypertrophy and preserved EF had myocardial scar on the DE MRI. Among them, 55 patients had a scar at the basal or middle interventricular septum, with a mesocardial or mesocardial-to-subepicardial distribution (Figs. 1 and 2). The remaining 4 patients had patchy, subendocardial scar, the locations of which were not consistent with coronary supply distribution. Ten of the 14 patients with ventricular tachyarrhythmia had the myocardial scar on the DE MRI (Fig. 1). There were no significant differences in the presence of myocardial scar and cine MRI parameters between the 2 patient groups. The number of scarred myocardial segment was significantly greater in patients with ventricular tachyarrhythmia than in those without arrhythmia, although there was overlap of the number between the patient groups (2.7 vs 1.3 segments, P = 0.011, Table 2, Fig. 3). The PPV and NPV for the arrhythmia were as follows: 0.17 and 0.92 for the presence of myocardial scar; 0.26 and 0.94 for the 2 scarred segments; and 0.33 and 0.94 for the 3 or more scarred segments. In the multivariate analysis, a family history of HCM and the number of scarred segment were significantly related to ventricular tachyarrhythmia (P < 0.01). A family history of HCM carried odds ratio of 11.1 (95% confidence index, 3.2–38.3) for the occurrence of arrhythmia.
DISCUSSION This study demonstrated that the number of scarred segment, but not its presence, on the DE MRI was the significant MRI parameter related to ventricular tachyarrhythmia in HCM with the morphology of basal septal hypertrophy and preserved EF. The number of scarred segment was significantly greater and the family history of HCM was observed more frequently in patients with the tachyarrhythmia than in those without it. Delayed enhancement magnetic resonance imaging may identify myocardial scar related to ventricular tachyarrhythmia in the HCM patients with basal septal hypertrophy and preserved EF, the most common type of HCM in clinical practice.
TABLE 1. MRI Parameters
1.5 T Cine DE 3.0 T Cine DE
TR, ms
TE, ms
Flip Angle, degree
Spatial Resolution, mm × mm
Slice Thickness/Gap, mm/mm
Averaging
2.8 9.3
1.4 4.6
60 10
1.88 × 1.65 1.83 × 1.61
8/2 10/0
1 2
4.1 10.0
2.0 2.9
55 15
1.61 × 1.65 1.77 × 1.18
8/2 10/0
1 1
Sensitivity encoding with a reduction factor of 1.3 to 2.0 was used for both cine and DE MRI. Cine indicates cine steady-state free precession with 20 cardiac phases; DE, inversion-recovery T1-weighted gradient-echo delayed enhancement imaging; TE, echo time; TR, repetition time.
68
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Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
J Comput Assist Tomogr • Volume 38, Number 1, January/February 2014
Delayed Enhancement in HCM
FIGURE 1. A 58-year-old woman with basal septal HCM associated with ventricular fibrillation. Delayed enhancement MRI in the short-axis view shows myocardial scar at the basal anterior and anterior septal regions (arrows). This patient has a family history of HCM, and has received an ICD.
Delayed enhancement magnetic resonance imaging is considered useful for risk stratification in HCM.6,15 However, the methodology used to assess myocardial scar differs between studies. Rubinshtein et al12 have reported that the presence or absence of myocardial DE is related to VT. The scar percent is shown to be significantly related to the arrhythmia in some reports,7,10,13,14 although the scar is defined as the region with the signal intensity plus 2 SD of the reference myocardium in 2 studies7,8 and 6 SD in another.10 A prospective study enrolling 202 HCM patients does not support a relationship between myocardial scar and arrhythmia or subsequent invasive treatments, whereas that study included various types of HCM.16 In the present study, we focused on HCM with basal septal hypertrophy and preserved LVEF, the most common type of HCM encountered in clinical practice, and we sought to examine whether MRI parameters were related to ventricular tachyarrhythmia in this condition. Consequently, the number of scarred myocardial segment was greater in the patients with
ventricular tachyarrhythmia. This had a significant association with ventricular tachyarrhythmia among the clinical and MRI parameters assessed, even when patient age and family history of HCM were included in the variables examined. This result is in line with those of a few previous studies.8,24 On the other hand, the presence of myocardial scar was not related to the occurrence of ventricular tachyarrhythmia in the present study. Ventricular tachyarrhythmia in HCM is reported to have a high NPV but a low PPV for sudden cardiac death.2,18 Nonetheless, some patients with ventricular tachyarrhythmia benefit from preventive ICD implantation.4,22,25 The number of scarred segments was significantly related to the arrhythmia, and its estimate may contribute to the decision making of ICD implantation. However, there was some overlap of the number of scarred segment between the patients with and without ventricular tachyarrhythmia. The NPV of the number of scarred segments for the tachyarrhythmia was high (>0.9), but the PPV was still moderate even when the threshold was defined the 3 or more
FIGURE 2. A 77-year-old woman with basal septal HCM without ventricular tachyarrhythmia. Delayed enhancement magnetic resonance imaging shows small myocardial scar (arrow). © 2014 Lippincott Williams & Wilkins
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TABLE 2. Association Between Patient Characteristics and MRI Parameters and Ventricular Tachyarrhythmia in HCM With Basal Septal Hypertrophy Variables Clinical Age, y Family history of HCM Cine MRI Maximum wall thickness, mm EF, % Myocardial mass, g DE MRI Presence of scar Number of scarred segment
All (n = 107)
Arrhythmia + (n = 14)
Arrhythmia − (n = 93)
P
65.4 (12.8) (17–86) 22
57.2 (14.7) (18–74) 9
66.6 (12.0) (17–86) 13
0.01
20.9 (5.3) (15.0–46.2) 67.5 (7.7) (50.8–89.7) 159.5 (49.9) (71.0–350.0)
22.7 (8.3) (15.1–46.2) 67.2 (6.2) (57.5–79.4) 153.3 (41.1) (82.0–253.0)
20.6 (4.7) (15.0–46.2) 67.6 (7.9) (50.8–89.7) 160.4 (51.0) (71.0–350.0)
10 2.7 (0–7)
49 1.3 (0–11)
59 1.5 (0–11)
Delayed Enhancement Magnetic Resonance Imaging in Hypertrophic Cardiomyopathy With Basal Septal Hypertrophy and Preserved Ejection Fraction: Relationship with Ventricular Tachyarrhythmia Yasuo Amano, MD,* Mitsunobu Kitamura, MD,† Masaki Tachi, MD,* Minako Takeda, MD,* Kyoichi Mizuno, MD,† and Shinichiro Kumita, MD* Objective: This study aimed to determine the relationship between delayed enhancement magnetic resonance imaging (DE MRI) and ventricular tachyarrhythmia in patients with hypertrophic cardiomyopathy (HCM) with basal septal hypertrophy and preserved ejection fraction (EF). Methods: One hundred seven patients with HCM with basal septal hypertrophy and EF greater than 50% underwent cine and DE MRI. Myocardial scar was identified with DE MRI. We assessed whether , patient s background, cine MRI findings, presence of myocardial scar, or number of scarred myocardial segments was related to the occurrence of ventricular tachyarrhythmia. Results: Patient,s age, family history of HCM, and number of scarred segments differed between the patients with and without the arrhythmia. A family history of HCM and number of scarred segments were significantly related to ventricular tachyarrhythmia (P < 0.01). Conclusions: The number of scarred segments is the significant DE MRI parameter related to ventricular tachyarrhythmia in HCM with basal septal hypertrophy and preserved EF. Key Words: hypertrophic cardiomyopathy, magnetic resonance imaging, delayed enhancement, myocardial scar, ventricular tachyarrhythmia (J Comput Assist Tomogr 2014;38: 67–71)
H
ypertrophic cardiomyopathy (HCM) is one of the leading causes of ventricular tachyarrhythmia and consequent sudden death.1–4 Myocardial scar or replacement fibrosis is related to ventricular tachyarrhythmia in HCM.5 Delayed enhancement magnetic resonance imaging (DE MRI) is useful for noninvasive detection of the myocardial scar related to regional hypertrophy and systolic function as well as that related to ventricular tachyarrhythmia.6,15 Delayed enhancement magnetic resonance imaging is expected to resolve clinical decision making, when risk stratification of HCM or indication for implantable cardioverter defibrillator (ICD) is inconclusive after assessing traditional risk markers HCM (eg, family history of sudden cardiac death and ventricular tachyarrhythmia) in each patient.4 In previous studies using DE MRI, the presence of myocardial scar, the number of scarred myocardial segments, the scar mass, or the scar percent have variously been reported to be predictors of arrhythmia.6,9,15 Conversely, Maron et al16 do not support a close relationship between the risk of ventricular
tachycardia (VT) and myocardial scar on DE MRI in a sizable population with HCM. These discrepancies may have arisen from the inclusion of various types of HCM. When end-stage HCM showing the dilated left ventricular (LV) cavity, lower ejection fraction (EF), or extensive scar is included, the frequency of ventricular tachyarrhythmia may increase.16,17 Moreover, the methodology of assessment of myocardial scar, irrespective of its relation to ventricular tachyarrhythmia, have varied in the previous studies.6,11,13,15,18,19 In the present study, we focused on HCM with basal septal hypertrophy and preserved EF (ie, >50%), the most common type of HCM encountered in clinical practice. The purpose of this study was to examine whether the presence of scar, extent of scarred myocardial segments, or other MRI findings were related to ventricular tachyarrhythmia in the HCM.
MATERIALS AND METHODS Patients From June 2006 to February 2013, consecutive 144 patients with a diagnosis of HCM underwent contrast-enhanced MRI. The diagnosis of HCM was based on echocardiography and MRI demonstration of LV myocardial hypertrophy greater than or equal to 15 mm and a nondilated LV cavity in the absence of other myocardial diseases, possibly producing LV hypertrophy. Basal septal hypertrophy was defined as the maximum basal septal thickness greater than or equal to 15 mm with a ratio between the anteroseptal and posterior wall thicknesses greater than 1.3 on cine steady-state free precession MRI at end-diastole.20,21 The indications for MRI examinations were the imaging diagnosis of HCM, measurement of myocardial thickness, myocardial mass, and cardiac function, identification of myocardial scar, or imaging study before alcohol septal ablation. The 25 patients with apical HCM, 6 with midventricular HCM, and 6 with impaired EF less than or equal to 50% were excluded from the study. Consequently, the 107 HCM patients were enrolled in this study, and comprised 37 men and 70 women, aged 17 to 86 years (65.4 [12.8] years). All patients gave their informed consent for participating MRI study, and the Institutional Ethics Committee approved this investigation.
Ventricular Tachyarrhythmia From the Departments of *Radiology, and †Cardiology, Nippon Medical School, Tokyo, Japan. Received for publication April 19, 2013; accepted June 29, 2013. Reprints: Yasuo Amano, MD, Department of Radiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan (e-mail: [email protected]). All authors declared no conflict of interests related to this article. Copyright © 2014 by Lippincott Williams & Wilkins
Ventricular tachyarrhythmia before MRI studies were noted based on the medical reports. The ventricular tachyarrhythmia included VT (ie, sustained VT, non-sustained VT of greater than or equal to 3 beats at 120 beats per minute, and repeated nonsustained VT) or ventricular fibrillation observed with electrocardiography (ECG) or Holter ECG in the patients with clinical symptoms.1,4,10,22
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Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
67
J Comput Assist Tomogr • Volume 38, Number 1, January/February 2014
Amano et al
RESULTS
Magnetic Resonance Imaging Magnetic resonance imaging examinations were performed with a 1.5-T (n = 59) or 3.0-T scanner (n = 48) with a 5- or 6channel cardiac phased-array coil (Philips Healthcare, Best, the Netherlands). All cardiac images were gated to vector ECG and were obtained during multiple breath-holding. Two-dimensional cine steady-state free precession and DE images encompassing the entire LV myocardium were acquired in the short-axis view. Two-chamber long-axis views were also acquired with 2dimensional cine and DE imaging. The DE MRI was acquired using an inversion-recovery segmented T1-weighted gradientecho imaging sequence 10 minutes after a gadolinium injection at a dose of 0.15 mmol/kg (Gd-DTPA, Gd-DTPA-BMA, or Gd-DOTA). The myocardial signal was nullified based on LookLocker T1-scout imaging in each patient.23 The typical imaging parameters for the cine and DE MRI are shown in Table 1.
Analysis The maximum wall thickness at end-diastole, EF, and myocardial mass of the left ventricle were measured using short-axis cine imaging. A dedicated workstation was used for these analyses (ViewForum, Philips). Either a reader with 16-year experience in cardiac MRI or the other with 3-year experience analyzed cine imaging in the clinical routine. Myocardial scar was also visually identified if it was seen in greater than or equal to 2 slices and had bright signal by each reader. Thereafter, the scar was confirmed when its mean signal intensity of scar was greater than the mean signal intensity plus 6 standard deviation (SD) of the reference myocardium in each slice on the DE MRI.10,19 Continuous variables were expressed as means (SD). Categorical data were presented as patient numbers. The presence of a family history of HCM and myocardial scar were compared between patients with and without tachyarrhythmia. The patient's age, and maximum wall thickness, EF, and myocardial mass of the left ventricle, and number of American Heart Association segments with myocardial scar were also compared. Fisher exact test or an unpaired t test was used for comparison. We calculated positive and negative predictive values (PPV and NPV) of the number of scarred segments for the ventricular tachyarrhythmia. For the clinical or MRI variables with the statistical significance, a multivariate analysis with forward selection method was used to assess association between the variables and the occurrence of ventricular tachyarrhythmia. A P < 0.05 was defined as statistically significant. The odds ratios were calculated for the selected categorical data.
Among 107 HCM patients with basal septal hypertrophy and preserved EF, a family history of HCM was found in 22 (20.1%) patients. Fourteen (13.1%) patients presented with ventricular tachyarrhythmia. The patients with ventricular tachyarrhythmia were significantly younger (P = 0.01) and had family history of HCM more frequently (P < 0.01) than those without the arrhythmia. Fifty-nine (53.2%) of the 107 HCM patients with basal septal hypertrophy and preserved EF had myocardial scar on the DE MRI. Among them, 55 patients had a scar at the basal or middle interventricular septum, with a mesocardial or mesocardial-to-subepicardial distribution (Figs. 1 and 2). The remaining 4 patients had patchy, subendocardial scar, the locations of which were not consistent with coronary supply distribution. Ten of the 14 patients with ventricular tachyarrhythmia had the myocardial scar on the DE MRI (Fig. 1). There were no significant differences in the presence of myocardial scar and cine MRI parameters between the 2 patient groups. The number of scarred myocardial segment was significantly greater in patients with ventricular tachyarrhythmia than in those without arrhythmia, although there was overlap of the number between the patient groups (2.7 vs 1.3 segments, P = 0.011, Table 2, Fig. 3). The PPV and NPV for the arrhythmia were as follows: 0.17 and 0.92 for the presence of myocardial scar; 0.26 and 0.94 for the 2 scarred segments; and 0.33 and 0.94 for the 3 or more scarred segments. In the multivariate analysis, a family history of HCM and the number of scarred segment were significantly related to ventricular tachyarrhythmia (P < 0.01). A family history of HCM carried odds ratio of 11.1 (95% confidence index, 3.2–38.3) for the occurrence of arrhythmia.
DISCUSSION This study demonstrated that the number of scarred segment, but not its presence, on the DE MRI was the significant MRI parameter related to ventricular tachyarrhythmia in HCM with the morphology of basal septal hypertrophy and preserved EF. The number of scarred segment was significantly greater and the family history of HCM was observed more frequently in patients with the tachyarrhythmia than in those without it. Delayed enhancement magnetic resonance imaging may identify myocardial scar related to ventricular tachyarrhythmia in the HCM patients with basal septal hypertrophy and preserved EF, the most common type of HCM in clinical practice.
TABLE 1. MRI Parameters
1.5 T Cine DE 3.0 T Cine DE
TR, ms
TE, ms
Flip Angle, degree
Spatial Resolution, mm × mm
Slice Thickness/Gap, mm/mm
Averaging
2.8 9.3
1.4 4.6
60 10
1.88 × 1.65 1.83 × 1.61
8/2 10/0
1 2
4.1 10.0
2.0 2.9
55 15
1.61 × 1.65 1.77 × 1.18
8/2 10/0
1 1
Sensitivity encoding with a reduction factor of 1.3 to 2.0 was used for both cine and DE MRI. Cine indicates cine steady-state free precession with 20 cardiac phases; DE, inversion-recovery T1-weighted gradient-echo delayed enhancement imaging; TE, echo time; TR, repetition time.
68
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© 2014 Lippincott Williams & Wilkins
Copyright © 2014 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
J Comput Assist Tomogr • Volume 38, Number 1, January/February 2014
Delayed Enhancement in HCM
FIGURE 1. A 58-year-old woman with basal septal HCM associated with ventricular fibrillation. Delayed enhancement MRI in the short-axis view shows myocardial scar at the basal anterior and anterior septal regions (arrows). This patient has a family history of HCM, and has received an ICD.
Delayed enhancement magnetic resonance imaging is considered useful for risk stratification in HCM.6,15 However, the methodology used to assess myocardial scar differs between studies. Rubinshtein et al12 have reported that the presence or absence of myocardial DE is related to VT. The scar percent is shown to be significantly related to the arrhythmia in some reports,7,10,13,14 although the scar is defined as the region with the signal intensity plus 2 SD of the reference myocardium in 2 studies7,8 and 6 SD in another.10 A prospective study enrolling 202 HCM patients does not support a relationship between myocardial scar and arrhythmia or subsequent invasive treatments, whereas that study included various types of HCM.16 In the present study, we focused on HCM with basal septal hypertrophy and preserved LVEF, the most common type of HCM encountered in clinical practice, and we sought to examine whether MRI parameters were related to ventricular tachyarrhythmia in this condition. Consequently, the number of scarred myocardial segment was greater in the patients with
ventricular tachyarrhythmia. This had a significant association with ventricular tachyarrhythmia among the clinical and MRI parameters assessed, even when patient age and family history of HCM were included in the variables examined. This result is in line with those of a few previous studies.8,24 On the other hand, the presence of myocardial scar was not related to the occurrence of ventricular tachyarrhythmia in the present study. Ventricular tachyarrhythmia in HCM is reported to have a high NPV but a low PPV for sudden cardiac death.2,18 Nonetheless, some patients with ventricular tachyarrhythmia benefit from preventive ICD implantation.4,22,25 The number of scarred segments was significantly related to the arrhythmia, and its estimate may contribute to the decision making of ICD implantation. However, there was some overlap of the number of scarred segment between the patients with and without ventricular tachyarrhythmia. The NPV of the number of scarred segments for the tachyarrhythmia was high (>0.9), but the PPV was still moderate even when the threshold was defined the 3 or more
FIGURE 2. A 77-year-old woman with basal septal HCM without ventricular tachyarrhythmia. Delayed enhancement magnetic resonance imaging shows small myocardial scar (arrow). © 2014 Lippincott Williams & Wilkins
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TABLE 2. Association Between Patient Characteristics and MRI Parameters and Ventricular Tachyarrhythmia in HCM With Basal Septal Hypertrophy Variables Clinical Age, y Family history of HCM Cine MRI Maximum wall thickness, mm EF, % Myocardial mass, g DE MRI Presence of scar Number of scarred segment
All (n = 107)
Arrhythmia + (n = 14)
Arrhythmia − (n = 93)
P
65.4 (12.8) (17–86) 22
57.2 (14.7) (18–74) 9
66.6 (12.0) (17–86) 13
0.01
20.9 (5.3) (15.0–46.2) 67.5 (7.7) (50.8–89.7) 159.5 (49.9) (71.0–350.0)
22.7 (8.3) (15.1–46.2) 67.2 (6.2) (57.5–79.4) 153.3 (41.1) (82.0–253.0)
20.6 (4.7) (15.0–46.2) 67.6 (7.9) (50.8–89.7) 160.4 (51.0) (71.0–350.0)
10 2.7 (0–7)
49 1.3 (0–11)
59 1.5 (0–11)
