Ventricular Arrhythmias In Hypertrophic Cardiomyopathy Research Articles

Risk profiles for ventricular arrhythmias in hypertrophic cardiomyopathy through clustering analysis including left ventricular strain.

AimsThe prediction of ventricular arrhythmia (VA) in hypertrophic cardiomyopathy (HCM) remains challenging. We sought to characterize the VA risk profile in HCM patients through clustering analysis combining clinical and conventional imaging parameters with information derived from left ventricular longitudinal strain analysis (LV-LS). MethodsA total of 434 HCM patients (65% men, mean age 56 years) were included from two referral centers and followed longitudinally (mean duration 6 years). Mechanical and temporal parameters were automatically extracted from the LV-LS segmental curves of each patient in addition to conventional clinical and imaging data. A total of 287 features were analyzed using a clustering approach (k-means). The principal endpoint was VA. Results4 clusters were identified with a higher rhythmic risk for clusters 1 and 4 (VA rates of 26%(28/108), 13%(13/97), 12%(14/120), and 31%(34/109) for cluster 1,2,3 and 4 respectively). These 4 clusters differed mainly by LV-mechanics with a severe and homogeneous decrease of myocardial deformation for cluster 4, a small decrease for clusters 2 and 3 and a marked deformation delay and temporal dispersion for cluster 1 associated with a moderate decrease of the GLS (p < 0.0001 for GLS comparison between clusters). Patients from cluster 4 had the most severe phenotype (mean LV mass index 123 vs. 112 g/m2; p = 0.0003) with LV and left atrium (LA) remodeling (LA-volume index (LAVI) 46.6 vs. 41.5 ml/m2, p = 0.04 and LVEF 59.7 vs. 66.3%, p < 0.001) and impaired exercise capacity (% predicted peak VO2 58.6 vs. 69.5%; p = 0.025). ConclusionProcessing LV-LS parameters in HCM patients 4 clusters with specific LV-strain patterns and different rhythmic risk levels are identified. Automatic extraction and analysis of LV strain parameters improves the risk stratification for VA in HCM patients.

Scar architecture affects the electrophysiological characteristics of induced ventricular arrhythmias in hypertrophic cardiomyopathy.

Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) detects myocardial scarring, a risk factor for ventricular arrhythmias (VAs) in hypertrophic cardiomyopathy (HCM). The LGE-CMR distinguishes core, borderzone (BZ) fibrosis, and BZ channels, crucial components of re-entry circuits. We studied how scar architecture affects inducibility and electrophysiological traits of VA in HCM. We correlated scar composition with programmed ventricular stimulation-inducible VA features using LGE intensity maps. Thirty consecutive patients were enrolled. Thirteen (43%) were non-inducible, 6 (20%) had inducible non-sustained, and 11 (37%) had inducible sustained mono (MMVT)- or polymorphic VT/VF (PVT/VF). Of 17 induced VA, 13 (76%) were MMVT that either ended spontaneously, persisted as sustained monomorphic, or degenerated into PVT/VF. Twenty-seven patients (90%) had LGE. Of these, 17 (57%) had non-sustained or sustained inducible VA. Scar mass significantly increased (P = 0.002) from non-inducible to inducible non-sustained and sustained VA patients in both the BZ and core components. Borderzone channels were found in 23%, 67%, and 91% of non-inducible, inducible non-sustained, and inducible sustained VA patients (P = 0.003). All 13 patients induced with MMVT or monomorphic-initiated PVT/VF had LGE. The origin of 10/13 of these VTs matched scar location, with 8/10 of these LGE regions showing BZ channels. During follow-up (20 months, interquartile range: 7-37), one patient with BZ channels and inducible PVT had an ICD shock for VF. Scar architecture determines inducibility and electrophysiological traits of VA in HCM. Larger studies should explore the role of complex LGE patterns in refining risk assessment in HCM patients.

Myocardial edema measured by T2 mapping is an independent predictor of ventricular arrhythmias in hypertrophic cardiomyopathy

Abstract Introduction Clinical outcome of patients with hypertrophic cardiomyopathy (HCM) largely depends on ventricular arrhythmias. Parametric T2 mapping from Cardiac MRI (CMR) was found to be a measure of myocardial edema. We sought to study whether elevated T2 values on CMR in patients with hypertrophic cardiomyopathy (HCM) might predict ventricular arrhythmias (VA) and adverse clinical outcome. Methods Consecutive patients with HCM (n = 59) and healthy volunteers (n = 21) underwent 3 Tesla CMR. T2 mapping values were independently analyzed by 2 independent readers and presented using a 16-segment AHA model. VA was recorded by 24-hour Holter monitoring and/or during exercise stress test. Composite outcome was defined as ventricular tachycardia (VT) per Holter and/or ergometry, admission due to arrhythmias, ICD insertion and all-cause mortality. Statistical analysis was a t-test for VA and multi-variant logistic regression model adjusted for age and gender. Results Septal and apical variants of HCM were found in 42 and 17 patients, respectively. We found good interobserver agreement in T2 values (ICC=0.92, 95% CI 0.86 - 0.96, p value &amp;lt;0.001). The 3rd tertile of T2 values (48 ± 8 msec) was significantly associated with VA 92% vs. 57 and 40% in lower tertiles, p = 0.02. Logistic regression analysis showed the 3rd tertile was an independent predictor of composite outcome (VT per Holter and/or ergometry, admission due to arrhythmias, ICD and all-cause mortality) OR 95% CI = 22.8 (1.4 - 361.6), p = 0.026. ROC analysis to find best cut-off of T2 for prediction of outcome showed AUC 0.7 (Figure 1). Conclusion Elevated T2 is an independent predictor of VA and adverse outcome in HMC patients. These results suggest the impact of myocardial edema in myocardial disease activity in HCM.ROC analysis to find best cut-off of T2

Abstract 16623: Extra-Cellular Volume Fraction Analysis on Cardiac CT is Useful for Predicting the Prognosis of Hypertrophic Cardiomyopathy

Introduction: Extra-Cellular volume fraction (ECV) analysis on MRI helps predict ventricular arrhythmia in hypertrophic cardiomyopathy (HCM). But the performance of cardiac MRI takes time, and there are also several contraindications. Cardiac CT is more versatile than cardiac MRI and is also helpful in screening coronary artery disease. We investigated the usefulness of ECV analysis on CT for the prognosis of HCM.Aim: To determine the utility of ECV analysis on CT to predict the prognosis in patients with HCM. Methods: Eighty-five HCM patients who underwent cardiac CT from December 2008 to March 2022 were analyzed. Left ventricular (LV) ECV (LV-ECV) on CT was measured, and we investigated the relationship between LV-ECV on CT and the major adverse cardiac events (MACEs) (cardiac death, fatal arrhythmia, and heart failure hospitalization) after CT. Results: All patients were followed for 69 ± 58 months after cardiac CT and 14 patients (16%) had MACEs. They had a significantly higher LV-ECV and lower ejection fraction (LVEF) than those without MACEs(42.4 ± 8.4% vs. 34.0 ± 7.0%, P=0.003, and (56.7 ± 11.8% vs. 66.7 ± 7.0%, P=0.011). The percentage of dilated phase HCM was significantly higher in the patients with MACEs than those without MACEs (21% vs 0%, p=0.003). LV-ECV was the only significant predictor of MACEs based on the multivariate analysis by Cox proportional hazard model (hazard ratio 1.13, 95% confidence interval 1.06-1.21). The optimal threshold of LV-ECV to predict MACEs was 37.59% based on the receiver operating characteristic analysis. The sensitivity and specificity of LV-ECV to predict MACEs were 79% and 75% at the best cut-off, and the area under the curve was 0.78 (Figure A). The patients with LV-ECV ≥ 37.59% (29 patients) had significantly higher MACEs than those with LV-ECV &lt; 37.59% during the follow-up periods (P &lt;0.001) (Figure B). Conclusion: ECV analysis on CT helped predict MACEs in HCM cases.

Systolic blood pressure ≤110 mm Hg is associated with severe coronary microvascular ischemia and higher risk for ventricular arrhythmias in hypertrophic cardiomyopathy

Systolic blood pressure ≤110 mm Hg is associated with severe coronary microvascular ischemia and higher risk for ventricular arrhythmias in hypertrophic cardiomyopathy

Predicting lethal ventricular arrhythmias in hypertrophic cardiomyopathy using non-electrophysiologic methods: Invasive EGM vs. non-invasive ECG analysis of fragmentation.

Predicting lethal ventricular arrhythmias in hypertrophic cardiomyopathy using non-electrophysiologic methods: Invasive EGM vs. non-invasive ECG analysis of fragmentation.

Mechanical dispersion detected by speckle tracking echocardiography as a risk marker for ventricular arrhythmia in hypertrophic cardiomyopathy

Mechanical dispersion detected by speckle tracking echocardiography as a risk marker for ventricular arrhythmia in hypertrophic cardiomyopathy

Catheter Ablation for Ventricular Arrhythmias in Hypertrophic Cardiomyopathy.

Implantable cardioverter-defibrillators are the mainstay of therapy for prevention of sudden cardiac death in high-risk patients with hypertrophic cardiomyopathy (HCM). Catheter ablation is a useful option for patients with recurrent, drug refractory monomorphic ventricular tachycardia (VT), and device therapy. Compared with other nonischemic substrates, there are limited data on the role and outcomes of catheter ablation in HCM. The challenges of VT ablation in HCM patients include deep intramural and epicardial substrates, suboptimal power delivery, and higher recurrence due to progression of disease. Patient selection, using cardiac MRI scar localization, and optimizing ablation techniques can improve outcomes in these patients.

Ventricular arrhythmia and sudden cardiac death in hypertrophic cardiomyopathy: From bench to bedside.

Patients with hypertrophic cardiomyopathy (HCM) mostly experience minimal symptoms throughout their lifetime, and some individuals have an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). How to identify patients with a higher risk of ventricular arrythmias and SCD is the priority in HCM research. The American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) both recommend the use of risk algorithms to identify patients at high risk of ventricular arrhythmias, to be selected for implantation of implantable cardioverters/defibrillators (ICDs) for primary prevention of SCD, although major discrepancies exist. The present SCD risk scoring systems cannot accurately identify early-stage HCM patients with modest structural remodeling and mild disease manifestations. Unfortunately, SCD events could occur in young asymptomatic HCM patients and even as initial symptoms, prompting the determination of new risk factors for SCD. This review summarizes the studies based on patients' surgical specimens, transgenic animals, and patient-derived induced pluripotent stem cells (hiPSCs) to explore the possible molecular mechanism of ventricular arrhythmia and SCD. Ion channel remodeling, Ca2+ homeostasis abnormalities, and increased myofilament Ca2+ sensitivity may contribute to changes in action potential duration (APD), reentry circuit formation, and trigger activities, such as early aferdepolarization (EAD) or delayed afterdepolarization (DAD), leading to ventricular arrhythmia in HCM. Besides the ICD implantation, novel drugs represented by the late sodium current channel inhibitor and myosin inhibitor also shed light on the prevention of HCM-related arrhythmias. The ideal prevention strategy of SCD in early-stage HCM patients needs to be combined with gene screening, hiPSC-CM testing, machine learning, and advanced ECG studies, thus achieving individualized SCD prevention.

Association between Left Ventricular Wall Thickness and Heart Rate Variability with Complex Ventricular Arrhythmia in Hypertrophic Cardiomyopathy

Objective: To demonstrate the association between the maximal left ventricular (LV) wall thickness and the late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) and heart rate variability (HRV) with complex ventricular arrhythmia (VA) in patients with hypertrophic cardiomyopathy (HCM). Materials and Methods: The present study was a retrospective study. Fifty-seven HCM patients who underwent CMR and Holter monitoring at Siriraj Hospital, Bangkok, Thailand, were identified and included. Complex VA was defined as Lown grading system type 4a or 4b as couplet or non-sustained ventricular tachycardia. Standard deviation of normal RR-interval (SDNN) was used to assess HRV. Results: The authors studied 57 patients, 40 (70.2%) patients had LGE, and 13 (22.8%) patients had complex VA. Complex VA was demonstrated in 11 (27.5%) patients in the LGE group compared with two (11.8%) in those without (p=0.304), and four (57.1%), and nine (18.0%) in patients had a maximal LV wall thickness of 25 mm or more and less than 25 mm, respectively (p=0.041). SDNN was 100.98±29.82 ms versus 123.85±35.12 ms (p=0.015) in the LGE group compared with the no-LGE group, and 89.08±25.39 ms versus 113.34±33.06 ms (p=0.018) in patients with and without complex VA. Multivariate analysis showed significant associations of maximal LV wall thickness of 25 mm or more and SDNN of less than 105 ms with complex VA with odds ratios of 6.71 (95% confidence interval [CI] 1.09 to 41.14; p=0.040) and 5.15 (95% CI 1.14 to 23.30; p=0.033), respectively. Conclusion: In HCM patients, increased LV wall thickness and a reduction in SDNN are associated with complex VA. The present study supports the utility of CMR and HRV for risk stratification of patients with HCM. Keywords: Heart rate variability; Maximal left ventricular wall thickness; Complex ventricular arrhythmia; Hypertrophic cardiomyopathy

The Relationship between Cardiac Magnetic Resonance-Assessed Replacement and Interstitial Fibrosis and Ventricular Arrhythmias in Hypertrophic Cardiomyopathy

Non-sustained ventricular tachycardia (nsVT) creates the electrical basis for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). We aimed to evaluate the relationship between interstitial fibrosis on cardiac magnetic resonance (CMR) and nsVT in HCM. A total of 50 HCM patients underwent CMR with a 3 T scanner to determine the presence of replacement fibrosis expressed by late gadolinium enhancement (LGE), and interstitial fibrosis expressed by native T₁, post-contrast T₁, and extracellular volume (ECV). The incidence of nsVT was assessed by Holter monitoring. We detected nsVT in 14 (28%) out of 50 HCM patients. Replacement fibrosis expressed by LGE was present in 37 (74%) patients and only showed a trend towards a differentiation between the groups with and without nsVT (p = 0.07). However, the extent of LGE was clearly higher in the nsVT group (3.8 ± 4.9% vs. 7.94 ± 4.5%, p = 0.002) and was an independent predictor of nsVT in a multivariable regression analysis (OR 1.2; 95%CI 1.02–1.4; p = 0.02). No relationship was observed between interstitial fibrosis and nsVT. To conclude, it was found that it is not the mere presence but the actual extent of LGE that determines the occurrence of nsVT in HCM patients; the role of interstitial fibrosis remains unclear.

Mean Scar Entropy by Late Gadolinium Enhancement Cardiac Magnetic Resonance Is Associated With Ventricular Arrhythmias Events in Hypertrophic Cardiomyopathy.

Background: Ventricular arrhythmias are associated with sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). Previous studies have found the late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) was independently associated with ventricular arrhythmia (VA) in HCM. The risk stratification of VA remains complex and LGE is present in the majority of HCM patients. This study was conducted to determine whether the scar heterogeneity from LGE-derived entropy is associated with the VAs in HCM patients.Materials and Methods: Sixty-eight HCM patients with scarring were retrospectively enrolled and divided into VA (31 patients) and non-VA (37 patients) groups. The left ventricular ejection fraction (LVEF) and percentage of the LGE (% LGE) were evaluated. The scar heterogeneity was quantified by the entropy within the scar and left ventricular (LV) myocardium.Results: Multivariate analyses showed that a higher scar [hazard ratio (HR) 2.682; 95% CI: 1.022–7.037; p = 0.039] was independently associated with VA, after the adjustment for the LVEF, %LGE, LV maximal wall thickness (MWT), and left atrium (LA) diameter.Conclusion: Scar entropy and %LGE are both independent risk indicators of VA. A high scar entropy may indicate an arrhythmogenic scar, an identification of which may have value for the clinical status assessment of VAs in HCM patients.

B-PO03-165 MEAN SCAR ENTROPY PREDICTS VENTRICULAR ARRHYTHMIAS EVENTS IN HYPERTROPHIC CARDIOMYOPATHY USING LATE GADOLINIUM ENHANCEMENT CARDIAC MAGNETIC RESONANCE

Ventricular arrhythmias (VAs) is associated with sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). Previous studies have found late gadolinium enhanced (LGE) on cardiac magnetic resonance (CMR)was independently associated with VAs in HCM. Risk stratification of VAs remains complex and LGE is present in the majority of HCM patients. This study was to determine whether the LGE by CMR derived entropy within the scar and the left ventricular (LV) myocardium predicts VAs in HCM. Consecutive HCM patients with scar by LGE-CMR were included. Routine left ventricular function parameters including LV ejection fraction (LVEF) and %LGE defined as percentage of LGE to LV mass (%LGE) using software CVI 42. The scar heterogeneity, quantified by entropy within the scar and LV myocardium was derived. The presence of VAs was defined as previous aborted cardiac arrest, documented sustained ventricular tachycardia (VT) and non-stained VT (nsVT) by Holter or implantable cardiac devices (ICD) monitoring. A total of 68 HCM patients (54.6 ±14.3 years, 69.1% male, LVEF 67.2 ±12.9 %) with LGE CMR were enrolled with a median follow-up of 25 (IQR 13-13) months. Thirty-one patients in VAs group and 37 patients in No-VAs group were included. From multivariable analysis, higher entropy of the scar (Hazard ratio [HR] 2.682;95% confidence interval [CI]:1.022 to 7.037; P=0.039) was independently associated with VAs, after adjusting for LVEF, %LGE, the LV maximal wall thickness (MWT) and the left atrium (LA) diameter. High entropy within the scar was an independent predictor of VAs and may indicate an arrhythmogenic scar. It seemed to be valuable for assessing the clinical status of VAs in HCM patients.

Global Circumferential Strain by Cardiac Magnetic Resonance Tissue Tracking Associated With Ventricular Arrhythmias in Hypertrophic Cardiomyopathy Patients.

Background: Hypertrophic cardiomyopathy (HCM) is prone to myocardial heterogeneity and fibrosis, which are the substrates of ventricular arrhythmias (VAs). Cardiac magnetic resonance tissue tracking (CMR-TT) can quantitatively reflect global and regional left ventricular strain from different directions. It is uncertain whether the change of myocardial strain detected by CMR-TT is associated with VAs. The aim of the study is to explore the differential diagnostic value of VAs in HCM by CMR-TT.Materials and Methods: We retrospectively included 93 HCM patients (38 with VAs and 55 without VAs) and 30 healthy cases. Left ventricular function, myocardial strain parameters and percentage of late gadolinium enhancement (%LGE) were evaluated.Results: Global circumferential strain (GCS) and %LGE correlated moderately (r = 0.51, P < 0.001). HCM patients with VAs had lower left ventricular ejection fraction (LVEF), global radial strain (GRS), GCS, and global longitudinal strain (GLS), but increased %LGE compared with those without VAs (P < 0.01 for all). %LGE and GCS were indicators of VAs in HCM patients by multivariate logistic regression analysis. HCM patients with %LGE >5.35% (AUC 0.81, 95% CI 0.70–0.91, P < 0.001) or GCS >-14.73% (AUC 0.79, 95% CI 0.70–0.89, P < 0.001) on CMR more frequently had VAs. %LGE + GCS were able to better identify HCM patients with VAs (AUC 0.87, 95% CI 0.79–0.95, P < 0.001).Conclusion: GCS and %LGE were independent risk indicators of VAs in HCM. GCS is expected to be a good potential predictor in identifying HCM patients with VAs, which may provide important values to improve risk stratification in HCM in clinical practice.

Relation of Late Gadolinium Enhancement and Extracellular Volume Fraction to Ventricular Arrhythmias in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HC) represents a major cause of sudden cardiac death in young adults. Late gadolinium enhancement (LGE) and extracellular volume (ECV) by T1 mapping are cardiac magnetic resonance (CMR) techniques to quantify fibrosis in HC. The relationships of LGE and ECV with ventricular arrhythmia, left ventricular (LV) diastolic function, and risk factors for sudden cardiac death (SCD) in HC are unclear. We studied 103 HC patients (mean age 51 ± 14, 42% women) who underwent CMR from 2012 to 2014. Global LGE and mean ECV were evaluated in relation to history of nonsustained ventricular tachycardia (NSVT), diastolic function by echocardiography, and SCD risk factors. LGE was present in 71 (69%) subjects. Wide variation was demonstrated in LGE (0.5% to 45.9%) and mean ECV (17.6% to 47.4%). Prevalence of NSVT increased continuously with LGE and was greater in subjects with ECV above the study population mean (27%). Increased LGE was associated with LV diastolic dysfunction and LV wall thickness. In conclusion, while ECV appears to have a threshold (27%) above which it is associated with NSVT, LGE demonstrates a more robust relationship with NSVT and measures of diastolic dysfunction.

1027 Mechanical dispersion of the left and right ventricle and the correlation with ventricular arrhythmias in hypertrophic cardiomyopathy

Abstract Funding Acknowledgements CREDO Project - ID: 49182, financed through the SOP IEC -A2-0.2.2.1-2013-1 cofinanced by the ERDF Introduction One important cause of sudden cardiac death in hypertrophic cardiomyopathy (HCM) are ventricular arrhythmias. In patients with HCM, non-sustained ventricular arrhythmias were analysed in relation with 2D speckle tracking mechanical dispersion of left ventricle (LVMD), but not in relation with mechanical dispersion of the right ventricle. Purpose To investigate the possible associations between mechanical dispersion and other echocardiographic parameters and the development of non-sustained ventricular tachycardias (NSVT) in HCM patients. Methods Clinical, 24 hours ECG-Holter, 2D and 3D echocardiography data were registered in HCM patients and in a healthy control group (with normal echocardiography). The 24 hours ECG-Holter was used for detecting NSVT. LVMD was calculated as the standard deviation of time to peak negative strain in the sixteenth segments of the left ventricle. The right ventricle mechanical dispersion (RVMD) was calculated on a three free wall segments model (FWMD), but also in six segments (three RV free wall segments plus three septal segments). Right and left ventricle function was evaluated by conventional echography and 2D speckle tracking imaging. Results Fifty-two patients with HCM and thirty-six age and sex matched subjects were included in the study. In HCM group, 6 patients (11,5%) associated biventricular hypertrophy, while 15 (28.8%) had NSVT on ECG monitoring (group HCM1). HCM1 patients had a much higher LVMD (77.38 ± 11.19 ms) compared with HCM patients without NSVT (group HCM2) (55.8 ± 23.85 ms, p = 0.001, CI:-33.9,-9.3) or compared with controls (43.07 ± 14.19 ms, p &amp;lt;0.001, CI: -44.68, -25.99). The 6 segments RVMD (60.23 ± 10.2 ms) was significantly higher in the CMH1 group compared with CMH2 (45.22 ± 9.8 ms, p = 0.01, CI: -32.1, -28.1) or with the control group (22 ±14 ms, p &amp;lt; 0.001,CI: -36.28, -30.12) independently of the existence of RV hypertrophy. Also, FWMD (55.2 ± 4.8 ms) was significantly higher in CMH1 group in comparation with CMH2 (42.3 ± 5.6 ms, p = 0.02, CI: -27.1, -8.2) or controls (32.1 ± 2.2 ms, p = 0.006, CI: -28.1, -12.1). The presence of NSVT correlated with global longitudinal strain (GS) 2C (-0.442, p = 0.009), GS LAX (r=-0.373, p = 0.03), GS mean value (r=-0.345, p = 0.046), LVMD (r = 0.462, p = 0.006), FWMD (r = 0.51, p = 0.004), 6 segments RVMD (r = 0.46, p = 0.05), 2D and 3D left atrial volume (r = 0.446, p = 0.008 and respectively, r = 0.512, p = 0.002). In a logistic regression, the only parameters associated with NSVT were LVMD (OR = 1.046, p = 0.05), FWMD (OR = 1.03, p = 0.05) and 6 segments MD (OR = 1.1, p = 0.04). Conclusions Increased mechanical dispersion of the left, but also right ventricle is associated with the risk of non-sustained ventricular tachycardias in HCM patients.

2378Blunted stress myocardial oxygenation and not myocardial perfusion reserve is associated with arrhythmic risk in hypertrophic cardiomyopathy

Abstract Background In hypertrophic cardiomyopathy (HCM), myocardial ischaemia is believed to play a role in fatal life-threatening ventricular arrhythmias and caused by microvascular dysfunction manifesting as impaired myocardial perfusion. However, previous studies suggest that myocardial oxygenation during vasodilator stress may also be blunted when perfusion is normal, due to increased metabolic demands conferred by energy-costly sarcomeric mutations, left ventricular hypertrophy and outflow obstruction. Whether or not impaired myocardial perfusion reserve or blunted stress oxygenation on cardiac magnetic resonance (CMR) predict the risk of ventricular arrhythmia in HCM is unknown. Purpose We sought to investigate if impaired myocardial perfusion reserve or stress oxygenation is associated with an increased risk of ventricular arrhythmia in HCM. Methods 103 genotyped HCM patients (mean age 47±15 years) and 32 age- and sex-matched healthy controls underwent adenosine stress blood oxygen level dependent (BOLD) imaging, first pass perfusion and late gadolinium imaging (LGE) on CMR to assess stress oxygenation (BOLD ΔSI), myocardial perfusion reserve index (MPRI), and fibrosis respectively. All HCM patients were monitored for ventricular tachycardia (≥3 beats, ≥120 beats per minute) on a 24-hour Holter. Results As expected, MPRI was significantly reduced in HCM (1.5±0.4 vs 2.0±0.3, p&lt;0.0001) compared to controls. Stress oxygenation response was blunted in HCM versus controls (9.1±4.1% vs 17.0±1.6%, p&lt;0.0001, Figure 1B). Twenty-six (25%) patients developed ventricular tachycardia on Holter monitoring. On univariate analysis, only stress oxygenation and not MPRI associated with ventricular tachycardia. The prevalence of ventricular tachycardia in HCM increased with decreasing quartiles of stress oxygenation (Figure 1D). HCM patients in the lowest quartile of oxygenation (BOLD ΔSI &lt;6.5%) were at a three-fold risk of ventricular tachycardia (OR 3.04, 95% confidence interval 1.02–9.05, p=0.04) on multivariable analysis (after adjusting for sudden cardiac death risk factors and LGE mass) compared to other patients. Sarcomeric mutation status was an independent determinant of stress oxygenation on multivariable analysis. Stress oxygenation was impaired in phenotype-negative sarcomeric mutation carriers (Sarc+P-, n=16) despite normal perfusion (Figure 1C, E). Sarcomeric HCM (Sarc+HCM) had more severe impairment in stress oxygenation than genotype negative HCM (G-HCM) and controls (Figure 1E). Figure 1 Conclusion In HCM, blunted stress-induced oxygenation is associated with an increased risk of ventricular arrhythmia and may represent a novel biomarker of arrhythmic risk. Sarcomeric mutation status is an important determinant of stress oxygenation response. Acknowledgement/Funding National Institute for Health Research Oxford Biomedical Centre and British Heart Foundation.

P2909Small left ventricular cavity size is related to ventricular arrhythmias in hypertrophic cardiomyopathy

P2909Small left ventricular cavity size is related to ventricular arrhythmias in hypertrophic cardiomyopathy

The T-peak-to-T-end interval: a novel ECG marker for ventricular arrhythmia and appropriate ICD therapy in patients with hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is associated with an increased risk of sudden cardiac death (SCD) primarily due to ventricular arrhythmia (VA). In patients (pts.) with a high risk of SCD, the implantation of an intracardiac cardioverter defibrillator (ICD) is thus indicated. Previous studies suggest that a prolonged interval between the peak and the end of the T wave, T-peak to T-end (TpTe), is associated with an elevated risk of VA and SCD in various clinical settings. The aim of our study was to evaluate the association between TpTe and VA in HCM pts. with a previously implanted ICD. In 40 HCM pts. (51.4 ± 16.4years; 62.5% men), TpTe was measured using the baseline digital standard resting 12-lead ECG during sinus rhythm. VA was assessed by device follow-up. Within 41.8 ± 35.1 months, 7 (17.5%) pts. had VA leading to appropriate therapy (AT), 7 pts. (17.5%) had non-sustained VA, and 26 pts. (65.0%) had no VA. The maximum TpTe was significantly prolonged in pts. with VA leading to AT compared to pts. without VA (101.3 ± 19.6 vs. 79.9 ± 15.3ms; p = 0.004). Maximum TpTe was associated with an elevated risk of VA leading to AT (hazard ratio per 10ms increase 1.63; 95% CI 1.04-2.54; p = 0.031) and pts. with a maximum TpTe ≤ 78ms were without any VA leading to AT during follow-up. There was no correlation of maximum TpTe to other clinical parameters in our patient cohort. A prolonged TpTe is associated with VA and AT in HCM. Our findings suggest that TpTe can possibly serve as a marker for ventricular arrhythmogenesis in pts. with HCM and assessment of TpTe might, therefore, optimize SCD risk stratification.

4789Non-invasive imaging of myocardial disarray associates with ventricular arrhythmia in hypertrophic cardiomyopathy

4789Non-invasive imaging of myocardial disarray associates with ventricular arrhythmia in hypertrophic cardiomyopathy