Metabolic changes in hibernating myocardium after percutaneous transluminal coronary angioplasty and the relation between recovery in left ventricular function and free fatty acid metabolism

123I-BMIPP/201Tl dual myocardial SPECT proves the efficacy of surgical treatment for an adult with Bland-White-Garland syndrome

Bland-White-Garland (BWG) syndrome is a rare congenital heart disease in which the left coronary artery originates from the pulmonary artery (PA). Surgical treatment to rebuild a dual coronary system is recommended at the time of the diagnosis. However, no effective operative procedure has been established for adult-type BWG patients because of the paucity of such cases. We herein report a case of adult-type BWG that was successfully treated by patch closure of the orifice of the left main tract from the main PA and coronary artery bypass grafting. ¹²³I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (BMIPP) and ²⁰¹thallium (Tl) dual myocardial single-photon emission computed tomography (SPECT) were performed before surgery, early after surgery, and at three months after surgery. Before surgery, dual SPECT showed myocardial perfusion defects in the anterior and septal wall, which corresponded to the cardiovascular magnetic resonance imaging findings. Early after surgery, only ²⁰¹Tl images demonstrated an improvement in the defect area. At three months after surgery, both the ²⁰¹Tl and ¹²³I-BMIPP imaging findings demonstrated an improvement in the defect area, which was correlated with the recovery of the left ventricular function. These results showed the effectiveness of this surgical approach for BWG syndrome. <Learning objective: Adult-type Bland-White-Garland syndrome is a rare congenital disease and no effective operative procedure has been established because of the paucity of such cases. The patient in this report underwent patch closure of the orifice of the left main tract from the main pulmonary artery and coronary artery bypass grafting. Myocardial dual single-photon emission computed tomography was considered to be effective for evaluating the results of revascularization surgery, and an improved uptake on ¹²³I-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid images was closely related to an improvement in the left ventricular function.>.

Cardiac event risk stratification in patients with end-stage renal disease: Sub-analysis of the B-SAFE study

BACKGROUND

The aim of this study was to investigate whether 123I-labelled β-methyl iodophenyl-pentadecanoic acid (BMIPP) imaging as an abnormal myocardial fatty acid metabolism indicator better predicted fatal and non-fatal cardiac events than conventional predictors [e.g. peripheral artery disease (PAD) and diabetes mellitus (DM)] in haemodialysis patients.

METHODS

In a sub-analysis of the BMIPP SPECT Analysis for Decreasing Cardiac Events in Haemodialysis Patients (B-SAFE) study, 677 asymptomatic patients with ≥1 cardiovascular risk factor and without known coronary artery disease were followed for 3 years. The amount of radioactivity in each 17-left ventricular segment was graded visually and assigned a score from 0 (normal) to 4 (absent). Its total values were designated as baseline summed BMIPP scores. Outcome measures were composite cardiac events.

RESULTS

Cardiac events correlated with age, PAD [hazard ratio (HR): 2.15; p=0.003], DM (HR: 1.76; p=0.006) and summed BMIPP scores (4-8, HR: 1.82; p<0.001; ≥9, HR: 3.49; p<0.001). Cardiac event-free rates decreased with increasing summed BMIPP scores, PAD and DM. Areas under the receiver operating curves (AUCs) indicated that a BMIPP-based model (AUC: 0.656) was more predictive than DM or PAD models (AUC: 0.591); a model with all three was most predictive (AUC: 0.708). The three-year cardiac event-free rates significantly decreased in patients with PAD and/or DM in all summed BMIPP score categories.

CONCLUSIONS

Abnormal myocardial fatty acid metabolism strongly predicts cardiac events in haemodialysis patients; those with PAD or DM are at high risk for cardiac events.

Microvascular obstruction on delayed enhancement cardiac magnetic resonance imaging after acute myocardial infarction, compared with myocardial (201)Tl and (123)I-BMIPP dual SPECT findings

BACKGROUND

The hypo-enhanced regions within the hyper-enhanced infarct areas detected by cardiac magnetic resonance (CMR) imaging reflect microvascular obstruction (MO) after acute myocardial infarction (AMI). The combined myocardial thallium-201 ((201)Tl)/iodine-123-15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid ((123)I-BMIPP) dual single-photon emission computed tomography (SPECT) is a useful tool for detecting myocardial reversibility after AMI. We evaluated whether MO could be an early predictor of irreversible myocardial damage in comparison with (201)Tl and (123)I-BMIPP dual SPECT findings in AMI patients.

METHODS

Sixty-two patients with initial AMI who successfully underwent coronary revascularization were enrolled. MO was defined by CMR imaging. Patients were divided into 2 groups as follows: MO group (n=32) and non-MO group (n=30). Scintigraphic defect scores were calculated using a 17-segment model with a 5-point scoring system. The mismatch score (MMS) was calculated as follows: the total sum of (Σ) (123)I-BMIPP defect score minus Σ(201)Tl defect score. The percentage mismatch score (%MMS) was calculated as follows: MMS/(Σ(123)I-BMIPP score)×100 (%).

RESULTS

The percentage infarct size (%IS) was significantly greater in the MO group than in the non-MO group (32.2±13.8% vs. 18.3±12.1%, p<0.001). The %MMS significantly correlated with the %IS and the percentage MO (r=-0.26, p=0.03; r=-0.45, p<0.001, respectively). The %MMS was significantly greater in the non-MO group than in the MO group (45.4±42.4% vs. 13.3±28.0%, p=0.001), and was an independent predictor for MO (OR 0.97, 95%CI 0.94-0.99, p=0.02).

CONCLUSIONS

Our results reconfirm that, in comparison with myocardial dual scintigraphy, MO is an important structural abnormality. CMR imaging is useful for the early detection of irreversible myocardial damage after AMI.

Inhibition of oxygen sensors as a therapeutic strategy for ischaemic and inflammatory disease

Cells in the human body need oxygen to function and survive, and severe deprivation of oxygen, as occurs in ischaemic heart disease and stroke, is a major cause of mortality. Nevertheless, other organisms, such as the fossorial mole rat or diving seals, have acquired the ability to survive in conditions of limited oxygen supply. Hypoxia tolerance also allows the heart to survive chronic oxygen shortage, and ischaemic preconditioning protects tissues against lethal hypoxia. The recent discovery of a new family of oxygen sensors--including prolyl hydroxylase domain-containing proteins 1-3 (PHD1-3)--has yielded exciting novel insights into how cells sense oxygen and keep oxygen supply and consumption in balance. Advances in understanding of the role of these oxygen sensors in hypoxia tolerance, ischaemic preconditioning and inflammation are creating new opportunities for pharmacological interventions for ischaemic and inflammatory diseases.

Relationship between the mismatch of 123I-BMIPP and 201Tl myocardial single-photon emission computed tomography and autonomic nervous system activity in patients with acute myocardial infarction

The purpose of this study was to elucidate the relationship between the mismatch of thallium-201(Tl) and iodine-123-beta-methyl-iodophenyl-pentadecanoic acid (BMIPP) myocardial single-photon emission computed tomography (SPECT) and autonomic nervous system activity in myocardial infarction (MI) patients. The subjects were 40 patients (34 males, 6 females) who underwent examinations by 123I-BMIPP and 201Tl myocardial SPECT imaging and 24-hour Holter monitoring within a 3-day period 3 weeks after the onset of their first MI. R-R intervals were analyzed every hour over a period of 24 hours by fast Fourier transformation (FFT). High frequency (HF) and low frequency (LF) were defined as markers of cardiac vagal activity in the former and the LF/HF ratio as sympathetic activity. Greater or more extensive decreases in the BMIPP image than that in the Tl image were defined as a positive mismatch. Patients were divided into positive and negative mismatch groups of 20 patients each. There were no significant differences between the 2 groups in age, sex, site of infarction, max CK (creatine kinase), max CK-MB, or left ventricular ejection fraction. The incidences of clinical signs suggesting residual myocardial ischemia were significantly greater in the positive than in the negative mismatch group (P < 0.05). The mean values for HF over the entire 24-hour period and over the 5-hour nocturnal period (0-5 AM) in the positive mismatch group were both significantly lower than those in the negative mismatch group (P < 0.001 in both groups). The 24-hour mean HF and mean nighttime HF in patients with signs of residual ischemia were both significantly lower than in those without signs of residual ischemia in the positive mismatch group (P < 0.05 in both groups). The mean LF/HF ratio for both the entire 24-hour and the nocturnal period in the positive mismatch group were significantly higher than those in the negative mismatch group (P < 0.001, P < 0.05, respectively). The daily profile of hourly HF measurements was significantly lower in the positive mismatch group than in the negative mismatch group (P < 0.02). The mean values of HF for 24-hour and 5-hour periods were significantly lower in patients with signs of residual ischemia in the positive mismatch group than in those with signs of residual ischemia in the negative mismatch group (P < 0.01, P < 0.02, respectively). There were no significant differences between the patients with signs of residual ischemia in the negative mismatch group and those without signs of residual ischemia in the positive and negative mismatch group with regard to the mean values of HF and the LF/HF ratio measured every hour for 24 hours and 5 hours. It is concluded from the present study that the findings of a mismatch on 123I-BMIPP and 201Tl myocardial SPECT 3 weeks after a first acute myocardial infarction with uncomplicated moderate or severe heart failure and decreased heart rate variability are related to residual myocardial ischemia. A combined assessment of heart rate variability in 24-hour Holter ECG monitoring and perfusion-metabolism mismatch in 123I-BMIPP and 201Tl myocardial SPECT is useful for determining residual myocardial ischemia in the follow-up of those with acute myocardial infarction.

Inhibition of very long chain acyl-CoA dehydrogenase during cardiac ischemia

The heart utilizes primarily fatty acids for energy production. During ischemia, however, diminished oxygen supply necessitates a switch from beta-oxidation of fatty acids to glucose utilization and glycolysis. Molecular mechanisms responsible for these alterations in metabolism are not fully understood. Mitochondrial acyl-CoA dehydrogenase catalyzes the first committed step in the beta-oxidation of fatty acids. In the current study, an in vivo rat model of myocardial ischemia was utilized to determine whether specific acyl-CoA dehydrogenases exhibit ischemia-induced alterations in activity, identify mechanisms responsible for changes in enzyme function, and assess the effects on mitochondrial respiration. Very long chain acyl-CoA dehydrogenase (VLCAD) activity declined 34% during 30 min of ischemia. Loss in activity appeared specific to VLCAD as medium chain acyl-CoA dehydrogenase activity remained constant. Loss in VLCAD activity during ischemia was not due to loss in protein content. In addition, activity was restored in the presence of the detergent Triton X-100, suggesting that changes in the interaction between the protein and inner mitochondrial membrane are responsible for ischemia-induced loss in activity. Palmitoyl-carnitine supported ADP-dependent state 3 respiration declined as a result of ischemia. When octanoyl-carnitine was utilized state 3 respiration remained unchanged. State 4 respiration increased during ischemia, an increase that appears specific to fatty acid utilization. Thus, VLCAD represents a likely site for the modulation of substrate utilization during myocardial ischemia. However, the dramatic increase in mitochondrial state 4 respiration would be predicted to accentuate the imbalance between energy production and utilization.

Mitochondrial preference for short chain fatty acid oxidation during coronary artery constriction

BACKGROUND

Reduced fatty acid oxidation in hypoperfused myocardium is believed to result from impaired oxidation in mitochondria. This study suggests another mechanism, that oxidative capacity exceeds regulated entry of long chain fatty acid (LCFA). The ability of myocardium to oxidize fatty acids and metabolize glucose during stenosis was examined in open chest, anesthetized pigs.

METHODS AND RESULTS

The left anterior descending (LAD) coronary artery was infused for 40 minutes (5 mL/min LAD) with [2-(13)C] butyrate (4 mmol/L), a short chain fatty acid (SCFA), plus [2-(13)C] glucose (10 mmol/L) in either nonischemic controls (n=4) or at the end of 5 hours of LAD flow reduction (40%, n=7). With LAD constriction, left ventricular wall thickening fell 45+/-8% (P<0.01). Despite glycolytic production of lactate and alanine, hypoperfused myocardium preferentially oxidized SCFA over endogenous LCFA. SCFA accounted for 63+/-4% (mean+/-SEM) of carbon units entering oxidation in both ischemic epicardium and endocardium versus only 38+/-4% and 40+/-6% in respective samples from normal myocardium (P<0.002). Unexpectedly, SCFA contributions were elevated in both endocardium and epicardium despite preserved epicardial blood flow versus a 58+/-9% drop in endocardial flow (P<0.05). No significant oxidation of glucose was evident, indicating that unlabeled fuels were primarily LCFA.

CONCLUSIONS

Because SCFA bypass LCFA transport into mitochondria, during LAD constriction, mitochondrial capacity to oxidize fatty acid exceeds LCFA entry for oxidation. Importantly, metabolic changes were disassociated from transmural tissue perfusion. These findings suggest that signals other than oxygen availability regulate fatty acid use during hypoperfusion.

Postrevascularization recovery of fatty acid utilization in ischemic myocardium: a randomized clinical trial of potassium channel opener

BACKGROUND

Abnormal fatty acid metabolism persists in hibernating myocardium, even after reperfusion. This study was designed to determine whether the K+ channel opener, nicorandil, improves fatty acid utilization after percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Patients undergoing elective PTCA were randomly assigned to treatment (group N, n = 26) or control groups (group C, n = 22). Group N received intracoronary and intravenous nicorandil during PTCA. Myocardial fatty acid use and perfusion were quantitatively evaluated by means of iodine-123-beta-methyl-p-iodophenyl-pentadecanoic acid single photon emission computed tomography (I-123 BMIPP SPECT) and thallium-201 (Tl-201) imaging before PTCA, 72 hours after PTCA, and 3 months after PTCA. Left ventricular function was also evaluated by means of contrast ventriculography before and 3 to 6 months after PTCA.

RESULTS

The 1-123 BMIPP defect score in group N significantly decreased, from 28%+/-13% to 20%+/-20% after PTCA and to 18%+/-17% 3 months later. In contrast, the I-123 BMIPP defect score in group C increased from 28%+/-20% to 36%+/-15% (P<.05 versus group N) after PTCA, then returned to 28%+/-17% (P<.05 versus group N) 3 months after PTCA. Recovery of left ventricular function paralleled the recovery of I-123 BMIPP uptake.

CONCLUSIONS

Nicorandil improves the recovery of myocardial fatty acid utilization and cardiac function after PTCA. K(ATP) channel activation may have a protective effect during coronary artery occlusion and improve subsequent recovery.