Changes in echocardiographic measures of systolic and diastolic function in children 1 year after hematopoietic SCT.

Hematopoietic SCT (HSCT) is a life-saving therapy in children, but has been associated with heart failure. Little is known about subclinical changes in cardiac function. We examined changes in systolic and diastolic function from pre- to 1-year post HSCT by echocardiography. All patients (n=74, 61% men, median age 9.1 years, mean left-ventricular (LV) ejection fraction 61.3±4.9%) who underwent HSCT at Children's Hospital Boston between 2005 and 2008, were <21 years at time of HSCT, and had routine pre- and 1-year post echocardiograms were included. Systolic function parameters, including LV ejection fraction, rate-corrected velocity of fiber shortening (Vcfc) and stress-velocity index and diastolic parameters, including tissue Doppler imaging (TDI)-derived velocities, and left-ventricular flow propagation, were compared before and after transplant. At 1-year post HSCT, systolic function, as measured by Vcfc (1.10±0.15 vs 1.04±0.12 circ/s; P=0.03) and stress-velocity index (z-score 0.40±1.4 vs -0.20±1.1; P=0.02), had worsened; diastolic function parameters, including mitral E' velocity (16.6±3.9 vs 15.0±3.4 cm/s; P=0.01) and tricuspid E' velocity (14.3±3.6 vs 12.4±2.8 cm/s; P=0.002) had also decreased. At 1-year post HSCT, children have subclinical declines in systolic and diastolic function. These small changes might become clinically important over time. Serial non-invasive assessment of cardiac function should be considered in all children following HSCT.

Safety and efficacy of carvedilol therapy for patients with dilated cardiomyopathy secondary to muscular dystrophy.

BACKGROUND: By the age of 20 years, almost all patients with Duchenne's or Becker's muscular dystrophy have experienced dilated cardiomyopathy (DCM), a condition that contributes significantly to their morbidity and mortality. Although studies have shown carvedilol to be an effective therapy for patients with other forms of DCM, few data exist concerning its safety and efficacy for patients with muscular dystrophy. This study aimed to evaluate the safety and efficacy of carvedilol for patients with DCM. METHODS: A clinical trial at an outpatient clinic investigated 22 muscular dystrophy patients, ages 14 to 46 years, with DCM and left ventricular ejection fraction (LVEF) less than 50%. Carvedilol up-titrated over 8 weeks then was administered at the maximum or highest tolerated dose for 6 months. Baseline and posttreatment cardiac magnetic resonance imaging (CMR), echocardiography, and Holter monitoring were recorded. RESULTS: Carvedilol therapy was associated with a modest but statistically significant improvement in CMR-derived ejection fraction (41% +/- 8.3% to 43% +/- 8%; p < 0.02). Carvedilol also was associated with significant improvements in both the mean rate of pressure rise (dP/dt) during isovolumetric contraction (804 +/- 216 to 951 +/- 282 mmHg/s; p < 0.05) and the myocardial performance index (0.55 +/- 0.18 to 0.42 +/- 0.15; p < 0.01). A trend toward improved shortening fraction, E/E' ratio, and isovolumetric relaxation time also was observed. Two patients had runs of nonsustained ventricular tachycardia exceeding 140 beats per minute (bpm) before carvedilol administration. Ventricular tachycardia exceeding 140 bpm was not observed after carvedilol therapy. Carvedilol was well tolerated, and no serious adverse events were identified. CONCLUSIONS: Carvedilol therapy appears to be safe for patients with DCM secondary to muscular dystrophy and produces a modest improvement in systolic and diastolic function.

Vascular endothelial growth factor delays onset of failure in pressure-overload hypertrophy through matrix metalloproteinase activation and angiogenesis.

OBJECTIVE: Pressure-overload hypertrophy is associated with decreased capillary density in myocardium resulting in impaired substrate delivery. Treatment of hypertrophied hearts with vascular endothelial growth factor (VEGF) induces angiogenesis. Since angiogenesis is associated with extracellular matrix degradation, we sought to determine whether VEGF induced angiogenesis in hypertrophy required matrix metalloproteinases (MMP) activation. METHODS: Newborn rabbits underwent aortic banding. Progression of hypertrophy (mass-to-volume (M/V) ratio) and mid-wall contractility index was monitored by echocardiography. At 4 and 6 weeks, VEGF (2 microg/kg), vehicle or VEGF combined with GM6001 (5 mg/kg), a MMP inhibitor, was administered intrapericardially. CD-31 (indicator of angiogenesis), MMP-2, MT1-MMP and TIMPs (endogenous MMP inhibitors) expression were measured by immunoblotting. MMP-2 activity was determined by gelatin zymography. RESULTS: Untreated hypertrophied hearts progressed to ventricular dilatation at 7 wks (M/V ratio: 0.75 +/- 0.07), but compensatory hypertrophy was maintained with VEGF (0.91 +/- 0.07; p < 0.05). LV contractility declined in untreated hearts from -0.41 +/- 0.9 (5 wks) to -0.73 +/- 0.5 (7 wks; p < 0.05) but remained normal with VEGF (+1.61 +/- 0.6 vs. +0.47 +/- 0.2). MMP-2 expression and activity were significantly elevated in VEGF treated hypertrophied hearts (p < 0.05) and were blocked by concomitant administration of GM6001. VEGF induced neovascularization was inhibited by addition of GM6001. MT1-MMP showed a trend to higher levels in VEGF treated hearts. TIMPs were unchanged in all three groups. CONCLUSIONS: Exogenous VEGF and resultant MMP-2 activation leads to increased capillary formation in severe hypertrophy, preventing progression to ventricular dilation and dysfunction. VEGF and the associated MMP-2 activation play an important and potentially therapeutic role in vascular remodeling of hypertrophied hearts.