Cardiac and Skeletal Muscle Energy Metabolism in Abnormal Growth Hormone States
Cardiac and Skeletal Muscle Energy Metabolism in Abnormal Growth Hormone States
Growth hormone (GH) is important for growth in childhood, but also has important effects on a
 number of tissues throughout life. GH deficiency and GH excess (acromegaly, caused by a
 pituitary tumour) are both cause serious abnormalities of metabolism and long-standing
 abnormal GH status causes abnormal heart function. In both cases cardiovascular disease is a
 leading cause of early (premature) death. In the current study we wish to investigate the
 energy status of the heart in patients with GH excess and deficiency and compare that with
 age-matched controls. We will perform a blood test to study metabolic parameters. We will
 perform measurements before treatment, after normalisation of improvement of GH levels and 2
 years after start of treatment.

 Objectives

 1. Determine cardiac and skeletal muscle energy metabolism in patients with GH excess
 (=acromegaly) or GH deficiency and detect changes after normalisation of GH and IGF-1
 levels. (IGF-I is a hormone directly influenced by GH)

 2. To correlate muscle energy metabolism parameters to GH and IGF-1 status in the control
 subjects and in both patient groups

 3. Determine the prevalence of coronary artery calcifications in patients with GH excess
 and GH deficiency and correlate this with their metabolic status

 4. To correlate coronary artery calcifications to abdominal obesity. Patients will be
 identified by Endocrinology physicians involved in the study in outpatients clinics or
 Endocrine wards and they will receive standard care for their disease. Tests related to
 endocrine hormone abnormalities will be performed as usual clinical practice. The study
 will involve three 3-hour visits to the Oxford Research Centre and two 1-hour visits to
 London Scanning Centre.

 The visits at the Oxford research centre will include Cardiac and skeletal investigations

 -  Standard cardiac MRI will be used to measure right and left ventricular morphology and
 global function.

 -  31P Magnetic Resonance Spectroscopy (MRS) to monitor heart muscle energy levels (by
 measuring intracellular PCr and ATP in heart muscle).

 -  Heart failure severity (so called 'NYHA status') will be determined from the 6 min walk
 test.

 -  Peak oxygen uptake will be estimated from a metabolic gas exchange analysis performed
 during maximal treadmill exercise testing.

 -  Skeletal muscle MR imaging and spectroscopy will be performed at rest and during
 exercise.

 -  Fasting blood test will be performed, see details in protocol.

 -  Electrocardiogram (ECG)

 -  Epworth Sleepiness Scale questionnaire and 5 point test for sleep apnoea The visits at
 the London Scanning Centre will include

 -  Electron beam coronary CT (EBCT) to assess coronary disease. The number of coronary
 disease lesions will be measured in several coronary arteries and values will add up to
 an overall score. In addition a single picture will be taken at the level of the
 umbilicus (belly button) to measure fat tissue within the abdomen. Patient selection:
 Patients will be recruited at St. Bartholomew's Hospital (Dr P. Jenkins and Prof. A.
 Grossman), King's Hospital (Dr S. Aylwin) and St Thomas's Hospital (Dr P. Carroll) in
 London, Royal Free Hospital (Prof P. Boloux), the John Radcliffe Hospital Oxford (Prof
 J. Wass), Addenbrooks Hospital Cambridge (Dr H. Simpson), Sheffield (Dr J.
 Newell-Price), and Stroke-on-Trent (Prof R. Clayton) from the Endocrine Wards and
 outpatient clinics. This constitutes a large recruitment base. We estimate that 45 new
 acromegaly patients and 60-80 new GHD patients per year will be screened. Patients will
 be selected on the basis of clinical diagnosis of acromegaly or GH deficiency (see
 details of these in the formal protocol).

 Patients will be managed according to the clinical protocols of the referring centre.

 The patients will have a report of their investigation results with their treating
 physicians.

 Control subjects will be selected from the general population via advertisements. They will
 undergo all tests in the Oxford centre once.

 Expected value of results:

 These studies will increase our knowledge of the metabolic changes associated with GH excess
 and GH deficiency, which can lead to increased cardiac morbidity and mortality in both cases.
 Our studies will help to clarify the mechanism of abnormal cardiac function. The study has
 been powered to have appropriate number of subjects within a two year period, therefore we
 anticipate that it will last from start to finish 4 years.
INTRODUCTION The effect of GH and IGF-I on the heart has been demonstrated in numerous
 experimental studies. GH and IGF-I receptors are expressed in cardiac myocytes, and IGF-I
 causes hypertrophy of cultured rat cardiomyocytes and delays cardiomyocyte apoptosis. In
 addition, GH and IGF-I have a direct effect on myocardial contractility, increasing the
 intracellular calcium content and enhancing the calcium sensitivity of myofilaments in
 cardiomyocytes. Clinical studies in patients with disorders of the GH/IGF-1 axis confirm the
 significant relationship between GH/IGF-I and the cardiovascular system. Interestingly, both
 GH excess and deficiency states are associated with abnormal cardiac function and with an
 attendant increased risk for cardiovascular morbidity and mortality in both. Our contention
 is that the apparent paradox of the relationship may be due to changes in the energy state of
 the myocardium in GH excess (acromegaly) and deficiency (GHD in hypopituitarism) and the
 inability of cellular metabolism to change appropriately between the competing demands of
 oxidative stress and anabolic processes. Data from the giant GH-overexpressing transgenic
 mouse demonstrate reduced creatinine phosphate-to-ATP ratio supporting an effect of GH on
 cardiac energy status.

 AMP-activated protein kinase (AMPK) is the energy sensor of the cell and has been shown to be
 an important regulator of cell metabolism, including cardiac cells (Dyck & Lopaschuk, 2002).
 AMPK is activated by rising AMP/ATP ratio, and programs intracellular metabolism to conserve
 energy for oxidate metabolism and to suspend anabolic processes. A substantial body of
 evidence testifies to the importance of AMPK and the associated regulation of myocardial
 energy status to cardiac function.

 -  Reduced activity of AMPK is a feature of inherited cardiomyopathies.

 -  Low energy status measured non-invasively is a predictor of death in dilated
 cardiomyopathy.

 -  Activation of AMPK reduces the injury in experimental models of ischaemia

 -  Reduced cardiac energy reserve is a feature of type 2 diabetes mellitus (T2DM), and
 cardiovascular death accounts for over 80% of mortality in T2DM.

 -  Drugs which are known to activate AMPK improve mortality in type 2 diabetes, such as
 metformin and glitazones (Kahn et al., 2005).

 -  Cannabinoids and ghrelin, first identified by our group to increase cardiac AMPK levels,
 have been shown to improve ischaemia-reperfusion injury (Frascarelli et al., 2003;
 Underdown et al., 2005; Shibata et al., 2005).

 Taking these experimental observations together, it can be inferred that in diabetic cardiac
 muscle, there is impaired activation of AMPK despite low energy levels, and potentially a
 failure of the normal mechanism to favour oxidative metabolism and cytoprotective functions
 during ischaemia.

 In patients, cardiac AMPK cannot be directly studied, although in a related animal study we
 will assess the effect of GH excess and deficiency on the activation of AMPK cardiac
 intracellular energy status and myocardium function. However, using 31P Magnetic Resonance
 Spectroscopy (MRS), in vivo measurement of high energy phosphate molecules can be assessed
 non-invasively and these have been shown in other diseases to have important clinical
 consequences. Specifically, both phosphocreatine (PCr), and ATP can be determined and ADP
 levels derived from the phosphocreatine:ATP ratio (Scheurmann-Freestone 2003). This approach
 has been recently used to demonstrate low ambient level of myocardial ADP in patients with
 T2DM. In the current study we will investigate the energy status in patients with acromegaly
 and GHD before and after normalisation of their GH status. We hypothesise that in untreated
 acromegaly, the unrestrained drive of anabolism will be associated with a low energy status,
 and particularly in inability to respond to exercise. We propose that in GHD, reduced
 anabolism will be associated with relatively high levels of energy but an impairment of
 muscle mass. We further anticipate that the normalisation of hormone levels resulting from
 either medical or surgical therapy will result in improvement in energy-storing phosphate
 molecule ratios in the myocardium.

 Acromegaly - Cardiac function Acromegalic cardiomyopathy is the specific myocardial disease
 of acromegaly (Clayton, 2003; Sacca et al., 2003; Colao et al., 2004b). Active acromegaly is
 associated with a 2- to 3-fold increase in mortality, mainly from cardiovascular disease,
 although with effective treatment the excess mortality can be reversed (Sheppard, 2005). In
 its early stages, acromegalic cardiomyopathy is characterised by increased left ventricular
 mass, with eccentric remodeling and normal diastolic function with a high cardiac output
 state with reduction of systemic vascular resistance (Fazio et al., 2000). In the next stage,
 increased heart mass and diastolic dysfunction, attributed to direct injury of the myocardium
 with GH hypersecretion, occur in the absence of associated diseases like hypertension,
 diabetes mellitus, and thyroid dysfunction. These abnormalities can progress to dilated
 cardiomyopathy and heart failure if acromegaly remains untreated for many years. There are
 specific structural changes in the myocardium with increased myocyte size and interstitial
 fibrosis of both ventricles. Left ventricular hypertrophy is common (in 64% of newly
 diagnosed cases) even in young patients with short duration of disease (Colao et al., 2003).
 Functionally, the main consequence of these changes is impaired left ventricular diastolic
 function, particularly when exercising, such that exercise tolerance is reduced (Colao et
 al., 2002). Myocardial perfusion is impaired in patients with active acromegaly as assessed
 by single photon emission computed tomography (SPECT), thus representing an early stage of
 cardiac involvement in acromegaly that may be directly mediated by GH excess (Herrmann et
 al., 2003). Some of these structural and functional changes can be reversed by effective
 treatment to lower serum GH levels to less than 1-2 ng/ml (glucose suppressed or random,
 respectively) and normalize IGF-I and long-term outcome and survival is improved (Colao et
 al., 2002; Jaffrain-Rea et al., 2003). Diastolic function improves with treatment, but the
 effect on exercise tolerance is more variable, and more longitudinal data are required to
 assess the benefits.

 Acromegaly - Coronary atherosclerosis Although coronary disease has a prevalence of 3-40% in
 acromegalic patients, there is considerable controversy whether this is directly related to
 GH excess. According to a well-controlled study (Otsuki et al., 2001) in which intima
 thickness was measured, the extent of atherosclerosis in the acromegalic patients was not
 higher than that in non-acromegalic subjects, and considering their increased number of
 atherosclerotic risk factors, such as lipid abnormalities, diabetes, increased homocystein,
 lipoprotein a, fibrinogen and platelet activator inhibitor 1 levels which are all strong
 predictors of coronary vascular disease, GH might therefore be even protective (Matta &
 Caron, 2003). In a recently described study with 79 acromegalic patients with 22 age-matched
 controls again no difference was observed in intima thickness (Paisley et al., 2006).
 Increased concentration of IGF-I - via its vasodilatotary effect mediated by nitric oxide -
 might be involved in the lack of susceptibility to atherosclerosis in some acromegalic
 patients. There are no previously published studies using electron beam coronary CT in this
 group of patients.

 Acromegaly - Skeletal muscle It is recognised that skeletal muscle in acromegaly fatigues
 rapidly but this has not been adequately explained, particularly in relation to the increase
 in muscle mass. It has been suggested that this may result from associated metabolic
 derangements (diabetes or thyroid abnormalities), or a direct effect of GH excess on muscle.
 Increase in muscle specific creatinine kinase levels have been detected in patients with
 active disease which improves with a reduction of serum GH (McNab & Khandwala, 2005) .
 Microscopic examination of skeletal muscle from acromegalic patients shows type 1 fibre
 hypertrophy (Nagulesparen et al., 1976).

 GHD - Cardiac function Patients with GH deficiency have an increased mortality due to
 cardiovascular disease. Most studies show decreases in heart function such as reduced left
 ventricular mass and cardiac output, and reduced left ventricular ejection fraction
 particularly during exercise; in addition there is an increased incidence of coronary artery
 disease (Colao et al., 2004a; Colao et al., 2004b; Svensson et al., 2005). The mechanism of
 cardiac abnormalities in GHD is debated, but most data support the hypothesis that GHD leads
 to reduced cardiac mass, reduced contractility, reduced pre-load and increased after-load,
 all of which could lead to reduced stroke-volume and reduced cardiac output (Colao et al.,
 2004b). Treatment with GH results in improvement in cardiac function and reduction of
 peripheral resistance due to direct anabolic actions of the myocardium but increased
 dimensions could also be secondary to an increased cardiac output and stroke volume as a
 result of increased contractility and increased pre-load. In conclusion, GHD is associated
 with cardiac dysfunction related to the degree and duration of GHD and GH replacement seems
 to enhance ventricular mass and cardiac function and to reverse diastolic abnormalities
 (Juul, 1996).

 GHD - Coronary sclerosis The evidence linking coronary sclerosis and GHD is robust although
 it is unclear whether this is a direct effect of GH deficiency on cardiac endothelium, or an
 indirect effect of the increase in cardiovascular risk factors documented in patients with
 hypopituitarism and GH deficiency. These include increased abdominal adiposity, abnormal LDL
 and triglyceride levels, high fibrinogen and plasminogen activator inhibitor activity,
 increased markers of inflammation (such as interleukin-6 and C-reactive protein) and
 consequently increased intima-thickness (Colao et al., 2004a; Colao et al., 2004b). In our
 studies, we will use electron-beam CT (EBCT) as a non-invasive means of determining coronary
 artery disease, which is a sensitive indicator of IHD. This will allow us to control for
 changes in the onset and/or recovery from ischaemia that might be due to macrovascular
 ischemia rather than reduced intracellular capacitance. There are no previously published
 studies using electron beam coronary CT in these groups of patients.

 GHD - Skeletal muscle Adult growth hormone deficiency (AGHD) is associated with fatigue,
 tiredness and isometric muscle strength is reduced to 76%. After 6 months of GH therapy,
 muscle mass increases 5% (Bengtsson et al., 1993; Juul, 1996). Neuromuscular dysfunction is
 also observed (abnormal electromyogram and interference pattern analysis) which improves
 after initiating GH therapy (Webb et al., 2003). The reduced exercise capacity observed in
 GHD is multifactorial but reduced skeletal muscle mass has an important contribution to it
 (Juul, 1996).

 In summary, existing evidence demonstrates that patients with both GH deficiency and GH
 excess have abnormal cardiac and skeletal muscle function, although the nature of the cardiac
 abnormality differs. In acromegaly there is hypertrophy and impaired contractility with
 dysfunction amplified during exercise. In GHD, risk factors for IHD cause premature occlusive
 coronary artery disease, coupled with a poor anabolic stimulus and reduced muscle mass.
 Skeletal muscle echoes these processes. . In transgenic mice overexpressing GH (an
 acromegalic mouse) the phosphocreatine -to-ATP ratio measured by MRS is significantly lower
 in GH overexpressing mice than controls, suggesting impaired energy level in the myocardium
 (Bollano et al., 2000). We hypothesise that chronic growth hormone excess may lead to reduced
 energy level within the myocardium, and that restoration of normal GH level will ameliorate
 this abnormality. Our model would also predict that in GHD resting energy levels would be
 normal or even high, and that the primary defect is a reduction in muscle mass due to reduced
 anabolic stimulus. In patients with GH excess and GHD we will assess cardiac energy levels
 with MRS, a non-invasive technique of assessing myocardial energy metabolism before and after
 treatment, a technique that has been successfully used to establish abnormal heart energy
 levels in patients with diabetes and heart failure (Scheuermann-Freestone et al., 2003).

 Objectives

 1. Determine cardiac (at rest) and skeletal muscle (at rest, peak exercise and recovery)
 energy metabolism in patients with GH excess and detect changes after normalisation of
 GH and IGF-1 levels

 2. Determine cardiac and skeletal muscle energy metabolism in patients with GH deficiency
 and detect changes after normalisation of IGF-1 levels

 3. To correlate muscle energy metabolism parameters to GH and IGF-1 status in the control
 subjects and in both patient groups

 4. Determine the prevalence of coronary artery calcifications in patients with GH excess
 and GH deficiency and correlate with their risk factors and other surrogate markers of
 CHD (serum levels of high sensitivity CRP, lipoprotein (a), homocysteine, and insulin
 resistance (HOMA analysis).

 5. Determine the anatomical distribution of the atheromatous plaques within the coronary
 arteries and the extent of isolated plaques compared to diffuse disease.

 Methods Cardiac and skeletal investigations

 -  MRI at 1.5T (Siemens Sonata) will be used to measure right and left ventricular
 morphology and global function (Sandstede et al., 2005) (i.e. left and right ventricular
 systolic and end-diastolic volumes and ejection fractions). Tissue phase mapping will be
 used to measure radial and rotational tissue velocities for regional wall motion
 abnormalities and abnormal contractile patterns.

 -  31P MRS will be used as previously described (Crilley et al., 2000; Roest et al., 2001)
 to monitor intracellular PCr and ATP in heart muscle. Acquisition will be triggered
 using electrocardiographic gating. Cardiac diastolic function will be measured using
 cine MRI volume-time curves and tissue phase mapping parameters.

 -  Heart failure severity (NYHA status) will be determined from the degree of dyspnoea (6
 min walk test).

 -  Peak O2 uptake (MVO2) will be estimated from a metabolic gas exchange analysis performed
 during maximal treadmill cardiopulmonary exercise testing.

 -  Skeletal muscle MR imaging and spectroscopy: The protocol for the 31P MRS determination
 of calf muscle (gastrocnemius and soleus) metabolism at rest and during dynamic exercise
 is well established (Scheuermann-Freestone et al., 2003). A T1-weighted MR image will be
 used to determine the muscle cross-sectional area and 31P MRS of the gastrocnemius
 muscle will be performed at rest, during and after exercise. Each subject will lie in
 the 3T superconducting magnet with their calf overlying a 6 cm diameter surface coil.
 The muscle will be exercised by plantar flexion of the right ankle, lifting a weight of
 10% lean body mass a distance of 7 cm at a rate of 30/min. After acquisition of four
 spectra (each 1.25 min), the weight will be incrementally increased by 2% of lean body
 mass every other minute. The subject will exercise until stopping when fatigued and the
 muscle will then be studied during recovery. On retesting after therapy, exercise will
 continue again until the subject is stopped by fatigue (treatment may lengthen this
 time). Relative concentrations of Pi, PCr and ATP will be measured from their signal
 intensities in the spectra as described previously (Adamopoulos et al., 1999;
 Butterworth et al., 2000; Scheuermann-Freestone et al., 2003).

 -  Electron beam coronary CT (EBCT) to assess coronary disease. As calcium is deposited in
 the earliest stages of atheroma formation, EBCT can detect sub-clinical coronary disease
 many years before it results in ischaemia. The extent of coronary artery calcification
 reflects the overall impact of risk factors, both known and unknown, on the end organ,
 the arterial wall, and as such gives a superior predictive value over the Framingham
 risk assessment (Thompson & Partridge, 2004; Pletcher et al., 2004). EBCT scanning will
 be performed using a GE-IMATRON 300 scanner using a conventional protocol. Calcium
 deposition within coronary arteries will be assessed by total volume and by the Agatson
 correction. The number of plaques and calcium score will be measured in the left main
 artery, left anterior descending, left circumflex, and right coronary artery, in
 addition to an overall score.

 Other investigations will include: Demographic and clinical data (incl. medication) will be
 obtained for all patients and control subjects; ECG, Epworth Sleepiness Scale questionnaire
 and 5 point test for sleep apnoea, blood samples will be taken after a 12 h fast, after 30
 min rest, for glucose, lactate, free fatty acids, ketone bodies, insulin, triglyceride,
 cholesterol, HDL, LDL, ANP, BNP, noradrenalin, electrolytes, creatinine, creatinine kinase,
 uric acid, TNF-alpha, leptin, Hb and glycosylated Hb determinations. Apoprotein A/B, High
 sensitivity C-reactive protein, Lipoprotein (a), Homocysteine, Insulin (HOMA analysis),
 biochemistry and liver function, pregnancy test. Endocrine investigations will include
 Glucose tolerance tests (for acromegaly patient; for GHD if necessary), GH day-curve (a mean
 of 5 estimations throughout the day), serum IGF-I, pituitary and peripheral hormones (LH,
 FSH, cortisol, TFT, testo/E2, PRL), estimation of duration of the disease (the presumed
 duration of acromegaly will be estimated by comparison of patients' photographs taken over a
 1-3-decade span and by interviews to date the onset of acral enlargement and other clinical
 symptoms (Damjanovic et al., 2002; Colao et al., 2003)) Patient selection: Patients will be
 recruited at St. Bartholomew's Hospital (Dr P. Jenkins and Prof. A. Grossman), King's
 Hospital (Dr S. Aylwin) and St Thomas's Hospital (Dr P. Carroll) in London, Royal Free
 Hospital (Prof P. Boloux), the John Radcliffe Hospital Oxford (Prof J. Wass), Sheffield (Dr
 J. Newell-Price), and Stroke-on-Trent (Prof R. Clayton) from the Endocrine Wards and
 outpatient clinics. This constitutes a large recruitment base. We estimate that 45 new
 acromegaly patients and 60-80 new GHD patients per year will be screened. Patients will be
 selected on the basis of the clinical diagnosis of acromegaly [Acromegaly: typical signs and
 symptoms and biochemical evidence (GH > 1μg/l during OGTT, IGF-I above age-related reference
 range); GHD: a structural hypothalamo-pituitary defect, at least one other pituitary hormone
 deficiency, AGHDA score >11 (NICE criterion) and evidence of severe biochemical GHD (usually
 a peak GH response to an insulin or glucagon stress test of <3 μg/l)]. Patients will be
 managed according to the clinical protocols of the referring centre.

 Inclusion criteria for acromegaly

 -  Clinical and biochemical diagnosis of acromegaly. Thyroid and glucocorticoid replacement
 if necessary stable for at least 4 weeks before the study. Gonadotrophin status will be
 recorded and whenever possible patients will be studied in the same status

 -  Males and females aged 18-70 years willing to give informed consent

 -  At least 6 months after the onset of symptoms of acromegaly and on stable medication for
 heart failure treatment (if any) for at least 4 weeks prior to inclusion into the study

 -  Systolic blood pressure < 180 mmHg, diastolic blood pressure < 110 mmHg.

 Exclusion criteria:

 -  Change in medication in the preceding 4 weeks

 -  Patients on subcutaneous insulin therapy

 -  Hyperthyroidism

 -  Not being in sinus rhythm

 -  Unstable angina pectoris and decompensated heart failure (define as NYHA 3-4)

 -  Clinically significant valvular disease, clinically significant chronic obstructive
 pulmonary disease

 -  History of myocardial infarction or stroke within the last 6 months, major cardiac
 surgery within the last 6 months

 -  Significant history of drug- or alcohol abuse or unable to give informed consent

 -  Any other significant surgical or medical condition which would considerably affect
 results in view of the identifying clinician

 -  Typical contraindication for MR (e.g. metal implants in delicate positions, aneurysm
 clips, shrapnel injuries, pacemakers, internal defibrillators and severe claustrophobia)

 -  Pregnancy

 Inclusion criteria for GHD

 -  Clinical and biochemical diagnosis of GHD. All hormones replaced (if clinically
 necessary) except GH. Thyroid and glucocorticoid replacement if necessary stable for at
 least 4 weeks before the study. Gonadotrophin status will be recorded and whenever
 possible patients will be studied in the same status

 -  Males and females aged 18-70 years willing to give informed consent

 -  At least 6 months after the onset of symptoms of acromegaly and on stable medication for
 heart failure treatment (if any) for at least 4 weeks prior to inclusion into the study

 -  Systolic blood pressure < 180 mmHg, diastolic blood pressure < 110 mmHg.

 Exclusion criteria:

 -  Change in medication in the preceding 4 weeks

 -  Previous history of acromegaly

 -  Child-hood onset GHD

 -  Patients on subcutaneous insulin therapy metformin probably an exclusion

 -  Hyperthyroidism

 -  Not being in sinus rhythm

 -  Unstable angina pectoris and decompensated heart failure (define as NYHA 3-4)

 -  Clinically significant valvular disease, clinically significant chronic obstructive
 pulmonary disease

 -  History of myocardial infarction or stroke within the last 6 months, major cardiac
 surgery within the last 6 months?

 -  Significant history of drug- or alcohol abuse or unable to give informed consent

 -  Any other significant surgical or medical condition which would considerably affect
 results in view of the identifying clinician

 -  Typical contraindication for MR (e.g. metal implants in delicate positions, aneurysm
 clips, shrapnel injuries, pacemakers, internal defibrillators and severe claustrophobia)

 -  Pregnancy

 POST-TREATMENT ASSESSMENT Three months is estimated to be sufficient time to reach altered
 (improved) cardiac metabolism as assessed by MRS based on previous studies (K. Clarke
 manuscript submitted)). Therefore the first post-treatment assessment will be 3 months after
 biochemical cure.

 In acromegalic patients 3 months after documented biochemical remission (IGF-1 levels reached
 upper limit of age-related normal range and day-curve for GH mean < 2.5 mcg/l or GH < 1 mcg/l
 during OGTT) repeat MRI, MRS and biochemical investigations. If patient is not in biochemical
 remission by 24 months, then repeat investigation at 24 months after the start of therapy
 will be performed as the final assessment.

 In GHD patients 3 months after recorded completed dose titration (IGF-I values in the upper
 third of the age-related normal range) repeat MRI, MRS and biochemical investigations. If
 patient has not completed GH dose titration by 24 months, then repeat investigation at 24
 months after the start of GH therapy anyway.

 24 months after start of therapy repeat EBCT. There are data to suggest that for example
 changing lipid status can improve EBCT after 12 months of therapy (Achenbach et al., 2002)
 Age and sex matched control subjects will be recruited and studied according to the
 pre-treatment protocol. Males and females aged 18 to 75 years willing to give informed
 consent will be selected without endocrine or coronary disease, with further exclusion
 criteria as above.

 Power calculation:

 The primary endpoint will be a change in cardiac energetics, as assessed by 31P magnetic
 resonance spectroscopy (MRS) (expressed as PCr/ATP ratio). Power calculations using data from
 our cardiac 31P MRS study (Scheuermann-Freestone et al., 2003) showed a highly significant
 reduction in cardiac PCr/ATP from 2.49 +/- 0.31 to 1.55 +/- 0.37, a difference of 0.94. In
 order to find a biologically significant difference between groups of one standard deviation
 (SD) with 90% power at P< 0.05, we would need to include 21 subjects in each group. For a
 paired study, in which the effects of therapy were tested on the same patient, we would need
 to include 11 patients in each group to find a significant difference between groups of 1 SD
 with 90% power at P< 0.05, while for unpaired comparison with control subjects 15 patients
 are necessary. To allow for patient drop-outs we will include a minimum of 30 subjects in the
 studies. Secondary endpoints for all studies will include cardiac function (MRI) and skeletal
 muscle function and energetics (MRI and MRS, respectively).
Inclusion Criteria:

 for acromegaly

 -  Clinical and biochemical diagnosis of acromegaly. Thyroid and glucocorticoid
 replacement if necessary stable for at least 4 weeks before the study. Gonadotrophin
 status will be recorded and whenever possible patients will be studied in the same
 status

 -  Males and females aged 18-70 years willing to give informed consent

 -  At least 6 months after the onset of symptoms of acromegaly and on stable medication
 for heart failure treatment (if any) for at least 4 weeks prior to inclusion into the
 study

 -  Systolic blood pressure < 180 mmHg, diastolic blood pressure < 110 mmHg.

 for GHD

 -  Clinical and biochemical diagnosis of GHD. All hormones replaced (if clinically
 necessary) except GH. Thyroid and glucocorticoid replacement if necessary stable for
 at least 4 weeks before the study. Gonadotrophin status will be recorded and whenever
 possible patients will be studied in the same status

 -  Males and females aged 18-70 years willing to give informed consent

 -  At least 6 months after the onset of symptoms of acromegaly and on stable medication
 for heart failure treatment (if any) for at least 4 weeks prior to inclusion into the
 study

 -  Systolic blood pressure < 180 mmHg, diastolic blood pressure < 110 mmHg.

 Exclusion Criteria:

 for acromegaly

 -  Change in medication in the preceding 4 weeks

 -  Patients on subcutaneous insulin therapy

 -  Hyperthyroidism

 -  Not being in sinus rhythm

 -  Unstable angina pectoris and decompensated heart failure (define as NYHA 3-4)

 -  Clinically significant valvular disease, clinically significant chronic obstructive
 pulmonary disease

 -  History of myocardial infarction or stroke within the last 6 months, major cardiac
 surgery within the last 6 months

 -  Significant history of drug- or alcohol abuse or unable to give informed consent

 -  Any other significant surgical or medical condition which would considerably affect
 results in view of the identifying clinician

 -  Typical contraindication for MR (e.g. metal implants in delicate positions, aneurysm
 clips, shrapnel injuries, pacemakers, internal defibrillators and severe
 claustrophobia)

 -  Pregnancy

 for GHD

 -  Change in medication in the preceding 4 weeks

 -  Previous history of acromegaly

 -  Child-hood onset GHD

 -  Patients on subcutaneous insulin therapy metformin probably an exclusion

 -  Hyperthyroidism

 -  Not being in sinus rhythm

 -  Unstable angina pectoris and decompensated heart failure (define as NYHA 3-4)

 -  Clinically significant valvular disease, clinically significant chronic obstructive
 pulmonary disease

 -  History of myocardial infarction or stroke within the last 6 months, major cardiac
 surgery within the last 6 months?

 -  Significant history of drug- or alcohol abuse or unable to give informed consent

 -  Any other significant surgical or medical condition which would considerably affect
 results in view of the identifying clinician

 -  Typical contraindication for MR (e.g. metal implants in delicate positions, aneurysm
 clips, shrapnel injuries, pacemakers, internal defibrillators and severe
 claustrophobia)

 -  Pregnancy