3-Dimensional Strain Analysis of Hypertrophic Cardiomyopathy: Insights From the NHLBI International HCM Registry

BACKGROUND

Abnormal global longitudinal strain (GLS) has been independently associated with adverse cardiac outcomes in both obstructive and nonobstructive hypertrophic cardiomyopathy.

OBJECTIVES

The goal of this study was to understand predictors of abnormal GLS from baseline data from the National Heart, Lung, and Blood Institute (NHLBI) Hypertrophic Cardiomyopathy Registry (HCMR).

METHODS

The study evaluated comprehensive 3-dimensional left ventricular myocardial strain from cine cardiac magnetic resonance in 2,311 patients from HCMR using in-house validated feature-tracking software. These data were correlated with other imaging markers, serum biomarkers, and demographic variables.

RESULTS

Abnormal median GLS (> -11.0%) was associated with higher left ventricular (LV) mass index (93.8 ± 29.2 g/m2 vs 75.1 ± 19.7 g/m2; P < 0.0001) and maximal wall thickness (21.7 ± 5.2 mm vs 19.3 ± 4.1 mm; P < 0.0001), lower left (62% ± 9% vs 66% ± 7%; P < 0.0001) and right (68% ± 11% vs 69% ± 10%; P < 0.01) ventricular ejection fractions, lower left atrial emptying functions (P < 0.0001 for all), and higher presence and myocardial extent of late gadolinium enhancement (6 SD and visual quantification; P < 0.0001 for both). Elastic net regression showed that adjusted predictors of GLS included female sex, Black race, history of syncope, presence of systolic anterior motion of the mitral valve, reverse curvature and apical morphologies, LV ejection fraction, LV mass index, and both presence/extent of late gadolinium enhancement and baseline N-terminal pro-B-type natriuretic peptide and troponin levels.

CONCLUSIONS

Abnormal strain in hypertrophic cardiomyopathy is associated with other imaging and serum biomarkers of increased risk. Further follow-up of the HCMR cohort is needed to understand the independent relationship between LV strain and adverse cardiac outcomes in hypertrophic cardiomyopathy.

Predictors of Major Atrial Fibrillation Endpoints in the National Heart, Lung, and Blood Institute HCMR

OBJECTIVES

This study sought to identify predictors of major clinically important atrial fibrillation endpoints in hypertrophic cardiomyopathy.

BACKGROUND

Atrial fibrillation (AF) is a common morbidity associated with hypertrophic cardiomyopathy (HCM). The HCMR (Hypertrophic Cardiomyopathy Registry) trial is a prospective natural history study of 2,755 patients with HCM with comprehensive phenotyping.

METHODS

All patients received yearly telephone follow-up. Major AF endpoints were defined as requiring electrical cardioversion, catheter ablation, hospitalization for >24 h, or clinical decisions to accept permanent AF. Penalized regression via elastic-net methodology identified the most important predictors of major AF endpoints from 46 variables. This was applied to 10 datasets, and the variables were ranked. Predictors that appeared in all 10 sets were then used in a Cox model for competing risks and analyzed as time to first event.

RESULTS

Data from 2,631 (95.5%) patients were available for analysis after exclusions. A total of 127 major AF endpoints events occurred in 96 patients over 33.3 ± 12.4 months. In the final model, age, body mass index (BMI), left atrial (LA) volume index, LA contractile percent (active contraction), moderate or severe mitral regurgitation (MR), and history of arrhythmia the most important. BMI, LA volume index, and LA contractile percent were age-dependent. Obesity was a stronger risk factor in younger patients. Increased LA volume, reduced LA contractile percent, and moderate or severe MR put middle-aged and older adult patients at increased risk.

CONCLUSIONS

The major predictors of major AF endpoints in HCM include older age, high BMI, moderate or severe MR, history of arrhythmia, increased LA volume, and reduced LA contractile percent. Prospective testing of a risk score based on these parameters may be warranted.

Impact of vitamin D on cardiac structure and function in chronic kidney disease patients with hypovitaminosis D: a randomized controlled trial and meta-analysis

AIMS

Vitamin D deficiency is associated with cardiovascular events in chronic kidney disease (CKD) yet the impact of supplementation is controversial. Previous active vitamin D supplementation studies did not show improvement in cardiac structure or function but the effect of native vitamin D supplementation in CKD patients with low vitamin D levels is unknown. We have addressed this question via both a randomized double-blind prospective study and a meta-analysis of three randomized placebo-controlled studies.

METHODS AND RESULTS

We conducted a randomized double-blind, placebo-controlled trial of vitamin D supplementation in stable, non-diabetic, CKD three to four patients with circulating vitamin D <75nmol/L, who were receiving treatment with ACEi or ARB and had high-normal left ventricular (LV) mass. Patients were randomized to receive six directly observed doses of 100 000 IU cholecalciferol (n = 25) or matched placebo (n = 23). The primary endpoint was changed in LV mass index (LVMI) over 52 weeks, as assessed by cardiac magnetic resonance imaging. Secondary endpoints included changes in LV ejection fraction (LVEF); LV and right ventricular volumes and left and right atrial area. Vitamin D concentration increased with the administration of cholecalciferol. The change in LVMI with cholecalciferol [median (inter-quartile range), -0.25 g (-7.20 to 5.30)] was no different from placebo [-4.30 g (9.70 to 2.60)]. There was no difference in changes of LVEF; LV and right ventricular volumes and left and right atrial area. The meta-analysis of three 52-week, randomized placebo-controlled studies using active/native vitamin D supplementation showed no differences in LVMI measurements.

CONCLUSION

Vitamin D supplementation does not have beneficial effects on LV mass in CKD patients.

Distinct Subgroups in Hypertrophic Cardiomyopathy in the NHLBI HCM Registry

BACKGROUND

The HCMR (Hypertrophic Cardiomyopathy Registry) is a National Heart, Lung, and Blood Institute-funded, prospective registry of 2,755 patients with hypertrophic cardiomyopathy (HCM) recruited from 44 sites in 6 countries.

OBJECTIVES

The authors sought to improve risk prediction in HCM by incorporating cardiac magnetic resonance (CMR), genetic, and biomarker data.

METHODS

Demographic and echocardiographic data were collected. Patients underwent CMR including cine imaging, late gadolinium enhancement imaging (LGE) (replacement fibrosis), and T1 mapping for measurement of extracellular volume as a measure of interstitial fibrosis. Blood was drawn for the biomarkers N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin T (cTnT), and genetic analysis.

RESULTS

A total of 2,755 patients were studied. Mean age was 49 ± 11 years, 71% were male, and 17% non-white. Mean ESC (European Society of Cardiology) risk score was 2.48 ± 0.56. Eighteen percent had a resting left ventricular outflow tract (LVOT) gradient ≥30 mm Hg. Thirty-six percent had a sarcomere mutation identified, and 50% had any LGE. Sarcomere mutation-positive patients were more likely to have reverse septal curvature morphology, LGE, and no significant resting LVOT obstruction. Those that were sarcomere mutation negative were more likely to have isolated basal septal hypertrophy, less LGE, and more LVOT obstruction. Interstitial fibrosis was present in segments both with and without LGE. Serum NT-proBNP and cTnT levels correlated with increasing LGE and extracellular volume in a graded fashion.

CONCLUSIONS

The HCMR population has characteristics of low-risk HCM. Ninety-three percent had no or only mild functional limitation. Baseline data separated patients broadly into 2 categories. One group was sarcomere mutation positive and more likely had reverse septal curvature morphology, more fibrosis, but less resting obstruction, whereas the other was sarcomere mutation negative and more likely had isolated basal septal hypertrophy with obstruction, but less fibrosis. Further follow-up will allow better understanding of these subgroups and development of an improved risk prediction model incorporating all these markers.

Fabry Disease in Families With Hypertrophic Cardiomyopathy: Clinical Manifestations in the Classic and Later-Onset Phenotypes

BACKGROUND

The screening of Icelandic patients clinically diagnosed with hypertrophic cardiomyopathy resulted in identification of 8 individuals from 2 families with X-linked Fabry disease (FD) caused by GLA(α-galactosidase A gene) mutations encoding p.D322E (family A) or p.I232T (family B).

METHODS AND RESULTS

Familial screening of at-risk relatives identified mutations in 16 family A members (8 men and 8 heterozygotes) and 25 family B members (10 men and 15 heterozygotes). Clinical assessments, α-galactosidase A (α-GalA) activities, glycosphingolipid substrate levels, and in vitro mutation expression were used to categorize p.D322E as a classic FD mutation and p.I232T as a later-onset FD mutation. In vitro expression revealed that p.D322E and p.I232T had α-GalA activities of 1.4% and 14.9% of the mean wild-type activity, respectively. Family A men had markedly decreased α-GalA activity and childhood-onset classic manifestations, except for angiokeratoma and cornea verticillata. Family B men had residual α-GalA activity and developed FD manifestations in adulthood. Despite these differences, all family A and family B men >30 years of age had left ventricular hypertrophy, which was mainly asymmetrical, and had similar late gadolinium enhancement patterns. Ischemic stroke and severe white matter lesions were more frequent among family A men, but neither family A nor family B men had overt renal disease. Family A and family B heterozygotes had less severe or no clinical manifestations.

CONCLUSIONS

Men with classic or later-onset FD caused by GLA missense mutations developed prominent and similar cardiovascular disease at similar ages, despite markedly different α-GalA activities.

Lack of Phenotypic Differences by Cardiovascular Magnetic Resonance Imaging in MYH7 (β-Myosin Heavy Chain)- Versus MYBPC3 (Myosin-Binding Protein C)-Related Hypertrophic Cardiomyopathy

BACKGROUND

The 2 most commonly affected genes in hypertrophic cardiomyopathy (HCM) are MYH7 (β-myosin heavy chain) and MYBPC3 (β-myosin-binding protein C). Phenotypic differences between patients with mutations in these 2 genes have been inconsistent. Scarce data exist on the genotype-phenotype association as assessed by tomographic imaging using cardiac magnetic resonance imaging.

METHODS AND RESULTS

Cardiac magnetic resonance imaging was performed on 358 consecutive genotyped hypertrophic cardiomyopathy probands at 5 tertiary hypertrophic cardiomyopathy centers. Genetic testing revealed a pathogenic mutation in 159 patients (44.4%). The most common genes identified were MYH7 (n=53) and MYBPC3 (n=75); 33.1% and 47% of genopositive patients, respectively. Phenotypic characteristics by cardiac magnetic resonance imaging of these 2 groups were similar, including left ventricular volumes, mass, maximal wall thickness, morphology, left atrial volume, and mitral valve leaflet lengths (all P=non-significant). The presence of late gadolinium enhancement (65% versus 64%; P=0.99) and the proportion of total left ventricular mass (%late gadolinium enhancement; 10.4±13.2% versus 8.5±8.5%; P=0.44) were also similar.

CONCLUSIONS

This multicenter multinational study shows lack of phenotypic differences between MYH7- and MYBPC3-associated hypertrophic cardiomyopathy when assessed by cardiac magnetic resonance imaging. Postmutational mechanisms appear more relevant to thick-filament disease expression and outcome than the disease-causing variant per se.

Effect of Omega-3 Acid Ethyl Esters on Left Ventricular Remodeling After Acute Myocardial Infarction: The OMEGA-REMODEL Randomized Clinical Trial

BACKGROUND

Omega-3 fatty acids from fish oil have been associated with beneficial cardiovascular effects, but their role in modifying cardiac structures and tissue characteristics in patients who have had an acute myocardial infarction while receiving current guideline-based therapy remains unknown.

METHODS

In a multicenter, double-blind, placebo-controlled trial, participants presenting with an acute myocardial infarction were randomly assigned 1:1 to 6 months of high-dose omega-3 fatty acids (n=180) or placebo (n=178). Cardiac magnetic resonance imaging was used to assess cardiac structure and tissue characteristics at baseline and after study therapy. The primary study endpoint was change in left ventricular systolic volume index. Secondary endpoints included change in noninfarct myocardial fibrosis, left ventricular ejection fraction, and infarct size.

RESULTS

By intention-to-treat analysis, patients randomly assigned to omega-3 fatty acids experienced a significant reduction of left ventricular systolic volume index (-5.8%, P=0.017), and noninfarct myocardial fibrosis (-5.6%, P=0.026) in comparison with placebo. Per-protocol analysis revealed that those patients who achieved the highest quartile increase in red blood cell omega-3 index experienced a 13% reduction in left ventricular systolic volume index in comparison with the lowest quartile. In addition, patients in the omega-3 fatty acid arm underwent significant reductions in serum biomarkers of systemic and vascular inflammation and myocardial fibrosis. There were no adverse events associated with high-dose omega-3 fatty acid therapy.

CONCLUSIONS

Treatment of patients with acute myocardial infarction with high-dose omega-3 fatty acids was associated with reduction of adverse left ventricular remodeling, noninfarct myocardial fibrosis, and serum biomarkers of systemic inflammation beyond current guideline-based standard of care.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00729430.

Significance of Late Gadolinium Enhancement at Right Ventricular Attachment to Ventricular Septum in Patients With Hypertrophic Cardiomyopathy

Cardiovascular magnetic resonance (CMR) with extensive late gadolinium enhancement (LGE) is a novel marker for increased risk for sudden death (SD) in patients with hypertrophic cardiomyopathy (HC). Small focal areas of LGE confined to the region of right ventricular (RV) insertion to ventricular septum (VS) have emerged as a frequent and highly visible CMR imaging pattern of uncertain significance. The aim of this study was to evaluate the prognostic significance of LGE confined to the RV insertion area in patients with HC. CMR was performed in 1,293 consecutive patients with HC from 7 HC centers, followed for 3.4 ± 1.7 years. Of 1,293 patients (47 ± 14 years), 134 (10%) had LGE present only in the anterior and/or inferior areas of the RV insertion to VS, occupying 3.7 ± 2.9% of left ventricular myocardium. Neither the presence nor extent of LGE in these isolated areas was a predictor of adverse HC-related risk, including SD (adjusted hazard ratio 0.82, 95% confidence interval 0.45 to 1.50, p = 0.53; adjusted hazard ratio 1.16/10% increase in LGE, 95% confidence interval 0.29 to 4.65, p = 0.83, respectively). Histopathology in 20 HC hearts show the insertion areas of RV attachment to be composed of a greatly expanded extracellular space characterized predominantly by interstitial-type fibrosis and interspersed disorganized myocyte patterns and architecture. In conclusion, LGE confined to the insertion areas of RV to VS was associated with low risk of adverse events (including SD). Gadolinium pooling in this region of the left ventricle does not reflect myocyte death and repair with replacement fibrosis or scarring.

Prognostic value of quantitative contrast-enhanced cardiovascular magnetic resonance for the evaluation of sudden death risk in patients with hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden death in the young, although not all patients eligible for sudden death prevention with an implantable cardioverter-defibrillator are identified. Contrast-enhanced cardiovascular magnetic resonance with late gadolinium enhancement (LGE) has emerged as an in vivo marker of myocardial fibrosis, although its role in stratifying sudden death risk in subgroups of HCM patients remains incompletely understood.

METHODS AND RESULTS

We assessed the relation between LGE and cardiovascular outcomes in 1293 HCM patients referred for cardiovascular magnetic resonance and followed up for a median of 3.3 years. Sudden cardiac death (SCD) events (including appropriate defibrillator interventions) occurred in 37 patients (3%). A continuous relationship was evident between LGE by percent left ventricular mass and SCD event risk in HCM patients (P=0.001). Extent of LGE was associated with an increased risk of SCD events (adjusted hazard ratio, 1.46/10% increase in LGE; P=0.002), even after adjustment for other relevant disease variables. LGE of ≥15% of LV mass demonstrated a 2-fold increase in SCD event risk in those patients otherwise considered to be at lower risk, with an estimated likelihood for SCD events of 6% at 5 years. Performance of the SCD event risk model was enhanced by LGE (net reclassification index, 12.9%; 95% confidence interval, 0.3-38.3). Absence of LGE was associated with lower risk for SCD events (adjusted hazard ratio, 0.39; P=0.02). Extent of LGE also predicted the development of end-stage HCM with systolic dysfunction (adjusted hazard ratio, 1.80/10% increase in LGE; P<0.03).

CONCLUSIONS

Extensive LGE measured by quantitative contrast enhanced CMR provides additional information for assessing SCD event risk among HCM patients, particularly patients otherwise judged to be at low risk.

Significance of left ventricular apical-basal muscle bundle identified by cardiovascular magnetic resonance imaging in patients with hypertrophic cardiomyopathy

AIMS

Cardiovascular magnetic resonance (CMR) has improved diagnostic and management strategies in hypertrophic cardiomyopathy (HCM) by expanding our appreciation for the diverse phenotypic expression. We sought to characterize the prevalence and clinical significance of a recently identified accessory left ventricular (LV) muscle bundle extending from the apex to the basal septum or anterior wall (i.e. apical-basal).

METHODS AND RESULTS

CMR was performed in 230 genotyped HCM patients (48 ± 15 years, 69% male), 30 genotype-positive/phenotype-negative (G+/P-) family members (32 ± 15 years, 30% male), and 126 controls. Left ventricular apical-basal muscle bundle was identified in 145 of 230 (63%) HCM patients, 18 of 30 (60%) G+/P- family members, and 12 of 126 (10%) controls (G+/P- vs. controls; P < 0.01). In HCM patients, the prevalence of an apical-basal muscle bundle was similar among those with disease-causing sarcomere mutations compared with patients without mutation (64 vs. 62%; P = 0.88). The presence of an LV apical-basal muscle bundle was not associated with LV outflow tract obstruction (P = 0.61). In follow-up, 33 patients underwent surgical myectomy of whom 22 (67%) were identified to have an accessory LV apical-basal muscle bundle, which was resected in all patients.

CONCLUSION

Apical-basal muscle bundles are a unique myocardial structure commonly present in HCM patients as well as in G+/P- family members and may represent an additional morphologic marker for HCM diagnosis in genotype-positive status.

Volumetric left ventricular ejection fraction is superior to 2-dimensional echocardiography for risk stratification of patients for primary prevention implantable cardioverter-defibrillator implantation

Current guidelines recommend an implantable cardioverter-defibrillator (ICD) according to the left ventricular ejection fraction (LVEF). However, they do not mandate volumetric LVEF assessment. We sought to determine whether volumetric LVEF measurement using cardiovascular magnetic resonance imaging (CMR-LVEF) is superior to conventional LVEF measurement using 2-dimensional transthoracic echocardiography (Echo-LVEF) for risk stratifying patients referred for primary prevention ICD. Patients who underwent primary prevention ICD implantation at our institution and had undergone preimplantation CMR-LVEF from November 2001 to February 2011 were identified. Volumetric CMR-LVEF was determined from cine short-axis data sets. CMR-LVEF and Echo-LVEF were extracted from the clinical reports. The end point was appropriate ICD discharge (shock and/or antitachycardia pacing). Of 48 patients, appropriate ICD discharge occurred in 9 (19%) within 29 ± 25 months (range 1 to 99, median 20). All patients met the Echo-LVEF criteria for ICD implantation; however 25% (95% confidence interval 13% to 37%) did not meet the CMR-LVEF criteria. None (0%) of these latter patients had received an appropriate ICD discharge. Using CMR-LVEF ≤30% as a threshold for ICD eligibility, 19 patients (40%) with a qualifying Echo-LVEF would not have been referred for ICD, and none (0%) received an ICD discharge.For primary prevention ICD implantation, volumetric CMR-LVEF might be superior to clinical Echo-LVEF for risk stratification and can identify a large minority of subjects in whom ICD implantation can be safely avoided. In conclusion, if confirmed by larger prospective series, volumetric methods such as CMR should be considered a superior "gatekeeper" for the identification of patients likely to benefit from primary prevention ICD implantation.

Risk Stratification and Outcome of Patients With Hypertrophic Cardiomyopathy ≥60 Years of Age

Background—

Hypertrophic cardiomyopathy (HCM) is prominently associated with risk for sudden death and disease progression, largely in young patients. Whether patients of more advanced age harbor similar risks is unresolved, often creating clinical dilemmas, particularly in decisions for primary prevention of sudden death with implantable defibrillators.

Methods and Results—

We studied 428 consecutive HCM patients presenting at ≥60 years of age and followed for 5.8±4.8 years; 53% were women. Of the 428 patients, 279 (65%) survived to 73±7 years of age (range, 61–96 years), most (n=245, 88%) with no/mild symptoms, including 135 with ≥1 conventional sudden death risk factors and 50 (37%) with late gadolinium enhancement. Over follow-up, 149 (35%) died at 80±8 years of age, mostly from non–HCM-related causes (n=133, 31%), including a substantial proportion from noncardiac disease (n=54). Sixteen patients (3.7%) had HCM-related mortality events (0.64%/y), including embolic stroke (n=6), progressive heart failure or transplantation (n=3), postoperative complications (n=2), and arrhythmic sudden death events (n=5, 1.2% [0.20%/y]). All-cause mortality was increased in HCM patients ≥60 years of age compared with an age-matched US general population, predominantly as a result of non–HCM-related diseases ( P <0.001; standard mortality ratio, 1.5).

Conclusions—

HCM patients surviving into the seventh decade of life are at low risk for disease-related morbidity/mortality, including sudden death, even with conventional risk factors. These data do not support aggressive prophylactic defibrillator implantation at advanced ages in HCM. Other cardiac or noncardiac comorbidities have a greater impact on survival than HCM in older patients.

Vitamin D reduces left atrial volume in patients with left ventricular hypertrophy and chronic kidney disease

BACKGROUND

Left atrial enlargement, a sensitive integrator of left ventricular diastolic function, is associated with increased cardiovascular morbidity and mortality. Vitamin D is linked to lower cardiovascular morbidity, possibly modifying cardiac structure and function; however, firm evidence is lacking. We assessed the effect of an activated vitamin D analog on left atrial volume index (LAVi) in a post hoc analysis of the PRIMO trial (clinicaltrials.gov: NCT00497146).

METHODS AND RESULTS

One hundred ninety-six patients with chronic kidney disease (estimated glomerular filtration rate 15-60 mL/min per 1.73 m(2)), mild to moderate left ventricular hypertrophy, and preserved ejection fraction were randomly assigned to 2 μg of oral paricalcitol or matching placebo for 48 weeks. Two-dimensional echocardiography was obtained at baseline and at 24 and 48 weeks after initiation of therapy. Over the study period, there was a significant decrease in LAVi (-2.79 mL/m(2), 95% CI -4.00 to -1.59 mL/m(2)) in the paricalcitol group compared with the placebo group (-0.70 mL/m(2) [95% CI -1.93 to 0.53 mL/m(2)], P = .002). Paricalcitol also attenuated the rise in levels of brain natriuretic peptide (10.8% in paricalcitol vs 21.3% in placebo, P = .02). For the entire population, the change in brain natriuretic peptide correlated with change in LAVi (r = 0.17, P = .03).

CONCLUSIONS

Forty-eight weeks of therapy with an active vitamin D analog reduces LAVi and attenuates the rise of BNP. In a population where only few therapies alter cardiovascular related morbidity and mortality, these post hoc results warrant further confirmation.

Prevalence and clinical profile of myocardial crypts in hypertrophic cardiomyopathy

BACKGROUND

In hypertrophic cardiomyopathy (HCM), cardiovascular MR can detect morphological abnormalities of the left ventricle (LV) not visualized with echocardiography. Although myocardial crypts (ie, narrow, blood-filled invaginations within the LV wall) have been recognized in HCM, all clinical implications of these structural abnormalities within the broad clinical HCM spectrum are not completely resolved. Therefore, we sought to characterize the prevalence and diagnostic significance of myocardial crypts in HCM patients.

METHODS AND RESULTS

Cine and late gadolinium enhancement cardiovascular MR and 2-dimensional echocardiography were obtained in 292 consecutive patients with HCM including 31 genotype-positive/phenotype-negative family members without LV hypertrophy (28 ± 16 years; 51% male) and 261 patients with LV hypertrophy (46 ± 18 years; 60% male). Ninety-eight subjects without cardiovascular disease were controls. Myocardial crypts (1-6/patient) were identified only by cardiovascular MR in 19 of 31 genotype-positive/phenotype-negative patients (61%) compared with only 10 of 261 (4%) patients with HCM with LV hypertrophy (P<0.001) and were absent in control subjects. Twelve-lead electrocardiograms were normal in 10 (53%) of the genotype-positive/phenotype-negative patients with crypts. Crypts were confined to the basal LV, most commonly in the ventricular septum (n=21) or posterior LV free wall (n=4), and associated with normal LV contractility and absence of late gadolinium enhancement in all but one patient.

CONCLUSIONS

LV myocardial crypts represent a distinctive morphological expression of HCM, occurring with different frequency in HCM patients with or without LV hypertrophy. Crypts are a novel cardiovascular MR imaging marker, which may identify individual HCM family members who should also be considered for diagnostic genetic testing. These data support an expanded role for cardiovascular MR in early evaluation of HCM families.

Vitamin D therapy and cardiac structure and function in patients with chronic kidney disease: the PRIMO randomized controlled trial

CONTEXT

Vitamin D is associated with decreased cardiovascular-related morbidity and mortality, possibly by modifying cardiac structure and function, yet firm evidence for either remains lacking.

OBJECTIVE

To determine the effects of an active vitamin D compound, paricalcitol, on left ventricular mass over 48 weeks in patients with an estimated glomerular filtration rate of 15 to 60 mL/min/1.73 m(2).

DESIGN, SETTING, AND PARTICIPANTS

Multinational, double-blind, randomized placebo-controlled trial among 227 patients with chronic kidney disease, mild to moderate left ventricular hypertrophy, and preserved left ventricular ejection fraction, conducted in 11 countries from July 2008 through September 2010.

INTERVENTION

Participants were randomly assigned to receive oral paricalcitol, 2 μg/d (n =115), or matching placebo (n = 112).

MAIN OUTCOME MEASURES

Change in left ventricular mass index over 48 weeks by cardiovascular magnetic resonance imaging. Secondary end points included echocardiographic changes in left ventricular diastolic function.

RESULTS

Treatment with paricalcitol reduced parathyroid hormone levels within 4 weeks and maintained levels within the normal range throughout the study duration. At 48 weeks, the change in left ventricular mass index did not differ between treatment groups (paricalcitol group, 0.34 g/m(2.7) [95% CI, -0.14 to 0.83 g/m(2.7)] vs placebo group, -0.07 g/m(2.7) [95% CI, -0.55 to 0.42 g/m(2.7)]). Doppler measures of diastolic function including peak early diastolic lateral mitral annular tissue velocity (paricalcitol group, -0.01 cm/s [95% CI, -0.63 to 0.60 cm/s] vs placebo group, -0.30 cm/s [95% CI, -0.93 to 0.34 cm/s]) also did not differ. Episodes of hypercalcemia were more frequent in the paricalcitol group compared with the placebo group.

CONCLUSION

Forty-eight week therapy with paricalcitol did not alter left ventricular mass index or improve certain measures of diastolic dysfunction in patients with chronic kidney disease.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00497146.

Intermediate-Signal-Intensity Late Gadolinium Enhancement Predicts Ventricular Tachyarrhythmias in Patients With Hypertrophic Cardiomyopathy

Background—

In hypertrophic cardiomyopathy (HCM), the arrhythmic potential associated with a variety of left ventricular myocardial signal intensities evident on contrast-enhanced cardiovascular magnetic resonance with late gadolinium enhancement (LGE) is unresolved.

Methods and Results—

In 145 HCM patients (43±15 years old), visually identified areas of LGE in left ventricle were analyzed quantitatively for intermediate (≥4 but <6 SD) and high (≥6 SD above the mean signal intensity of normal myocardium) LGE signal intensity (LGE-SI). Ambulatory Holter ECGs were obtained within 7.8±8.3 weeks of cardiovascular magnetic resonance. HCM patients with nonsustained ventricular tachycardia, ventricular couplets, and premature ventricular contractions showed greater amounts of intermediate LGE-SI (17±7 versus 10±10 g, 16±10 versus 10±11 g, and 13±8 versus 10±13 g, respectively; P =0.003 to <0.001) and greater amounts of high LGE-SI (15±6 versus 10±8 g, 14±9 versus 10±12 g, and 12±7 versus 10±8 g, respectively; P =0.02–0.003) than patients without these arrhythmias. In HCM patients with either nonsustained ventricular tachycardia, couplets, or premature ventricular contractions, the extent of intermediate LGE-SI exceeded that of high LGE-SI (17±7 versus 15±6 g, 16±10 versus 14±9 g, and 13±8 versus 12±7 g, respectively; P =0.01–0.04). In addition, the receiver operating characteristic area under the curve established intermediate LGE-SI as a better discriminator of patients with nonsustained ventricular tachycardia than was high LGE-SI, with 7 additional patients with this arrhythmia identified.

Conclusions—

In patients with HCM, intermediate LGE-SI is a better predictor of ventricular tachyarrhythmias (including nonsustained ventricular tachycardia, a risk factor for sudden death) than is high LGE-SI. Longitudinal studies in larger HCM cohorts are justified to define the independent prognostic impact of intermediate LGE-SI.

The use of group sequential, information-based sample size re-estimation in the design of the PRIMO study of chronic kidney disease

BACKGROUND

Chronic kidney disease is associated with a marked increase in risk for left ventricular hypertrophy and cardiovascular mortality compared with the general population. Therapy with vitamin D receptor activators has been linked with reduced mortality in chronic kidney disease and an improvement in left ventricular hypertrophy in animal studies.

PURPOSE

PRIMO (Paricalcitol capsules benefits in Renal failure Induced cardia MOrbidity) is a multinational, multicenter randomized controlled trial to assess the effects of paricalcitol (a selective vitamin D receptor activator) on mild to moderate left ventricular hypertrophy in patients with chronic kidney disease.

METHODS

Subjects with mild-moderate chronic kidney disease are randomized to paricalcitol or placebo after confirming left ventricular hypertrophy using a cardiac echocardiogram. Cardiac magnetic resonance imaging is then used to assess left ventricular mass index at baseline, 24 and 48 weeks, which is the primary efficacy endpoint of the study. Because of limited prior data to estimate sample size, a maximum information group sequential design with sample size re-estimation is implemented to allow sample size adjustment based on the nuisance parameter estimated using the interim data. An interim efficacy analysis is planned at a pre-specified time point conditioned on the status of enrollment. The decision to increase sample size depends on the observed treatment effect. A repeated measures analysis model, using available data at Week 24 and 48 with a backup model of an ANCOVA analyzing change from baseline to the final nonmissing observation, are pre-specified to evaluate the treatment effect. Gamma-family of spending function is employed to control family-wise Type I error rate as stopping for success is planned in the interim efficacy analysis.

LIMITATIONS

If enrollment is slower than anticipated, the smaller sample size used in the interim efficacy analysis and the greater percent of missing week 48 data might decrease the parameter estimation accuracy, either for the nuisance parameter or for the treatment effect, which might in turn affect the interim decision-making.

CONCLUSIONS

The application of combining a group sequential design with a sample-size re-estimation in clinical trial design has the potential to improve efficiency and to increase the probability of trial success while ensuring integrity of the study.

Suppression of aldosterone mediates regression of left ventricular hypertrophy in patients with hypertension

Background: High circulating aldosterone levels stimulate myocardial fibrosis and left ventricular hypertrophy (LVH). However, it is not clear whether suppression of aldosterone directly contributes to LVH regression in hypertensive patients.

Methods: The Aliskiren in Left Ventricular Hypertrophy (ALLAY) trial randomised 465 hypertensive overweight subjects with LVH to the direct renin inhibitor aliskiren 300 mg, losartan 100 mg or the combination and followed patients for 9 months. All patients were treated to standard blood pressure targets. Left ventricular (LV) mass index (LVMI) and LV wall thickness (LVWT) were assessed by cardiac magnetic resonance. A subset of 136 patients who had plasma aldosterone concentration (ALDO) measured at baseline and study end was analysed.

Results: At baseline, plasma ALDO was modestly related to systolic blood pressure, LVMI, and wall thickness (all, p < 0.05). Aliskiren, either alone or in combination, was associated with a significantly greater reduction from baseline to 9 months in plasma aldosterone than losartan alone ( p < 0.02). Reduction in ALDO was related to reduction in LVMI even after adjustment for baseline ALDO, BP reduction and treatment group ( p for trend = 0.042).

Conclusion: In hypertensive patients with increased LVWT, aliskiren alone or in combination with the angiotensin receptor blocker losartan provides greater reduction in aldosterone compared to losartan alone. Moreover, suppression of aldosterone was associated with reduction of LVH, independently of the change in SBP, suggesting that suppression of aldosterone, a known mediator of LVH, may be particularly important for LVH regression and as a target for therapy.

Vitamin D receptor activation and left ventricular hypertrophy in advanced kidney disease

BACKGROUND

In chronic kidney disease (CKD), left ventricular hypertrophy (LVH) is prevalent and is associated with increased cardiovascular morbidity and mortality. Vitamin D receptor (VDR) activation attenuates LVH progression in animal models.

METHODS

PRIMO is a multinational, randomized, double-blinded trial with oral paricalcitol in subjects with stages 3-4 CKD, mild-to-moderate LVH and an LV ejection fraction >50%. The primary endpoint is change in the left ventricular mass index (LVMI) compared with placebo after 48 weeks of treatment. The main secondary endpoints are changes in diastolic function parameters. In this paper, we report baseline characteristics from this study.

RESULTS

LVMI was 33.0 ± 7.5 g/m(2.7) for males and 30.8 ± 7.2 g/m(2.7) for females (p = 0.04). LVMI correlated with systolic blood pressure (r = 0.24), urine albumin creatinine ratio (r = 0.39), troponin T (r = 0.29), high-sensitivity C-reactive protein (r = 0.25) and plasma levels of B-type brain natriuretic peptide (r = 0.22); all p < 0.01. In multiple linear regression, each remained independently associated with LVMI. The early diastolic velocity of the lateral mitral annulus (E') was 8.1 ± 2.4 cm/s. E' was inversely correlated with age in univariate (r = -0.14, p = 0.04) and multivariable (p = 0.02) analysis.

CONCLUSION

Among 227 multinational subjects with stages 3-4 CKD, baseline LVMI correlates with baseline blood pressure, urine albumin creatinine ratio and cardiac biomarkers, and baseline diastolic function correlates with age. This research was funded by Abbott Laboratories; ClinicalTrials.gov No. NCT00497146.

Autologous cardiomyotissue implantation promotes myocardial regeneration, decreases infarct size, and improves left ventricular function

BACKGROUND

Cell therapy for myocardial infarction (MI) may be limited by poor cell survival and lack of transdifferentiation. We report a novel technique of implanting whole autologous myocardial tissue from preserved myocardial regions into infarcted regions.

METHODS AND RESULTS

Fourteen rats were used to optimize cardiomyotissue size with peritoneal wall implantation (300 μm identified as optimal size). Thirty-nine pigs were used to investigate cardiomyotissue implantation in MI induced by left anterior descending balloon occlusion (10 animals died; male-to-female transplantation for tracking with in situ hybridization for Y chromosome, n=4 [2 donors and 2 MI animals]; acute MI implantation cohort at 1 hour, n=13; and healed MI implantation at 2 weeks, n=12). Assessment included echocardiography, magnetic resonance imaging, hemodynamics, triphenyltetrazolium chloride staining, and histological and molecular analyses. Tracking studies demonstrated viable implants with donor cells interspersed in the adjacent myocardium with gap junctions and desmosomes. In the acute MI cohort, treated animals compared with controls had improved perfusion by magnetic resonance imaging (1.2±0.01 versus 0.86±0.05; P<0.01), decreased MI size (magnetic resonance imaging: left ventricle, 2.2±0.5% versus 5.4±1.5%, P=0.04; triphenyltetrazolium chloride: anterior wall, 10.3±4.6% versus 28.9±5.8%, P<0.03), and improved contractility (dP/dt, 1235±215 versus 817±817; P<0.05). In the healed MI cohort, treated animals had less decline in ejection fraction between 2 and 4 week assessment (-3±4% versus -13±-4%; P<0.05), less decline in ±dP/dt, and smaller MI (triphenyltetrazolium chloride, 21±11% versus 3±8%; P=0.006) than control animals. Infarcts in the treated animals contained more mdr-1(+) cells and fewer c-kit(+) cells with a trend for decreased expression of matrix metalloproteinase-2 and increased expression of tissue inhibitor of metalloproteinase-2.

CONCLUSION

Autologous cardiomyotissue implanted in an MI area remains viable, exhibits electromechanical coupling, decreases infarct size, and improves left ventricular function.

Widespread divergence between incipient Anopheles gambiae species revealed by whole genome sequences

The Afrotropical mosquito Anopheles gambiae sensu stricto, a major vector of malaria, is currently undergoing speciation into the M and S molecular forms. These forms have diverged in larval ecology and reproductive behavior through unknown genetic mechanisms, despite considerable levels of hybridization. Previous genome-wide scans using gene-based microarrays uncovered divergence between M and S that was largely confined to gene-poor pericentromeric regions, prompting a speciation-with-ongoing-gene-flow model that implicated only about 3% of the genome near centromeres in the speciation process. Here, based on the complete M and S genome sequences, we report widespread and heterogeneous genomic divergence inconsistent with appreciable levels of interform gene flow, suggesting a more advanced speciation process and greater challenges to identify genes critical to initiating that process.

Relation between infarct size in ST-segment elevation myocardial infarction treated successfully by percutaneous coronary intervention and left ventricular ejection fraction three months after the infarct

The goal of this analysis was to determine the relation between myocardial infarct size and left ventricular (LV) ejection fraction (EF) in patients with ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (pPCI) using cardiovascular magnetic resonance imaging (CMR). After STEMI, LVEF and infarct size correlate with prognosis, but the relation between infarct size and LVEF is incompletely known. Consecutive subjects presenting to a single center with STEMI treated with pPCI were enrolled, and cine functional and late gadolinium enhancement CMR was performed 3 months after presentation. From cine images, LVEF was calculated using volumetric summation of disks method. Infarct size was measured as percent LV myocardial volume with late gadolinium enhancement. In the 78 patients enrolled (mean age 54.5 years, range 42 to 82), median LVEF was 56% (interquartile range 49 to 62) and median infarct size was 11% (interquartile range 5 to 18). Of the 53 patients with infarct size <15%, all had LVEF >40%, and there was no significant relation between infarct size and LVEF (slope -0.43, R(2) = 0.045, p = 0.13). In patients with infarct size > or =15%, there was a significant negative linear association between infarct size and LVEF (slope -1.21, R(2) = 0.66, p <0.001), such that for every 5% increase in infarct size, there was a 6.1% decrease in LVEF. In conclusion, there is a negative linear relation between infarct size and LVEF for moderate to large infarcts. For small infarcts there is no significant relation between infarct size and LVEF. Up to 15% of LV myocardial volume may be infarcted before there is any appreciable decrease in LVEF.

Relation between myocardial infarct size and ventricular tachyarrhythmia among patients with preserved left ventricular ejection fraction following fibrinolytic therapy for ST-segment elevation myocardial infarction

In the era of early reperfusion therapy for ST-segment elevation myocardial infarction, preserved left ventricular (LV) function is common. Despite preservation of LV ejection fraction (LVEF), there remains a spectrum of risk for adverse cardiovascular events, including ventricular tachycardia (VT) and ventricular fibrillation (VF). Larger infarct size has been independently associated with death, VT/VF, and heart failure in the post-myocardial infarction population. It was hypothesized that infarct size, as estimated by peak serum creatine kinase (CK)-MB concentration, would be associated with the incidence of VT/VF in patients with preserved LV function after ST-segment elevation myocardial infarctions. The Clopidogrel as Adjunctive Reperfusion Therapy-Thrombolysis In Myocardial Infarction 28 (CLARITY-TIMI 28) study enrolled 3,491 patients with ST-segment elevation myocardial infarctions who underwent fibrinolytic therapy. The association between estimated infarct size (ratio of peak CK-MB to the upper limit of normal), the LVEF (measured using left ventriculography or echocardiography), and the incidence of VT/VF through 30 days was assessed. A total of 1,436 patients underwent assessments of LV function, of whom 1,133 had adequate CK-MB for analysis. The median LVEF in this group was 55% (interquartile range 45% to 65%), and most patients (n = 814 [87.1%]) had LVEF > or =40%. Among patients with LVEF > or =40%, the ratio of peak CK-MB to the upper limit of normal was significantly associated with the incidence of VT/VF through 30 days (2.2%, 3.7%, and 5.5% across tertiles, respectively, p = 0.041 for trend) and the incidence of the composite of cardiovascular death, heart failure, shock, and VT/VF through 30 days (3.7%, 6.0%, 8.5%, respectively, p = 0.018 for trend). In conclusion, in patients with ST-segment elevation myocardial infarction with preserved LV function after reperfusion therapy, larger infarct size, as estimated by peak serum CK-MB concentration, is significantly associated with VT/VF as well as other adverse clinical outcomes.

Association of Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade with cardiovascular magnetic resonance measures of infarct architecture after primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

BACKGROUND

Primary percutaneous coronary intervention (pPCI) routinely restores normal epicardial flow among patients with ST-segment elevation myocardial infarction (STEMI). However, impairment of myocardial perfusion frequently persists. The goal of this analysis was to determine whether impaired myocardial perfusion was associated with cardiovascular magnetic resonance-defined abnormalities in infarct architecture, including infarct size (IS), infarct surface area (ISA), infarct border zone (IBZ), and infarct complexity (IC).

METHODS

Thirty-one patients with STEMI treated with pPCI were included in the analysis. Cardiovascular magnetic resonance was performed within 7 days of presentation and repeated at 3 months. Infarct complexity was defined as the ratio of actual ISA to an idealized smooth ISA and normalized to IS.

RESULTS

Impaired Thrombolysis in Myocardial Infarction Myocardial Perfusion Grade (TMPG) (<3) was associated with larger ISA at baseline (78.2 +/- 25.3 cm(2) vs 40.3 +/- 30.3 cm(2), P = .02) and follow-up (58.8 +/- 27.5 cm(2) vs 26.3 +/- 20.2 cm(2), P = .03) and larger IBZ at follow-up (7.8% +/- 2.7% vs 4.1% +/- 3.3%, P = .02). At follow-up, ISA, when normalized to IS, was significantly higher among patients with impaired myocardial perfusion (TMPG <3) (6.9 +/- 2.5 vs 5.9 +/- 2.4 cm(2)/%, P = .03). Thrombolysis in MI myocardial perfusion grade <3 was also associated with increased IC at follow-up (52% +/- 12% vs 33% +/- 16%, P = .01).

CONCLUSIONS

Impaired TMPG is associated with larger ISA, IBZ, and increased IC. At 3 months, TMPG remained associated with ISA and IC after adjusting for IS, suggesting that impaired TMPG after pPCI is associated with infarct architecture after healing, independent of IS.