Myocardial fatty acid utilisation during exercise induced ischemia in patients with coronary artery disease

Summary

Aim: Reversible or irreversible myocardial damage due to ischemia correlates with altered membrane functions of the cells. To compare myocardial free fatty acid (FFA) metabolism and flow during exercise induced ischemia we studied ten patients with coronary artery disease but without previous myocardial infarction. Methods: A series of post-exercise single-photon emission computed tomography (SPECT) measurements was performed after injection of ¹²³I labelled heptadecanoic acid (HDA). Myocardial perfusion was estimated from the separately performed exercise-redistribution thallium study. Fatty acid metabolic rate, thallium uptake and washout were calculated for anterior, lateral, posterior and septal segments. Results: The more reduced post-exercise FFA metabolic rate (–63 ±18%, mean ±1 SD) compared to flow (–36 ±16%) was related to the severity of myocardial ischemia and wall motion abnormalities. Conclusion: In this small group of patients, the reduced post-exercise FFA metabolic rate tentatively suggests a parsimonious workload of the exercising myocardium by reducing oxygen consumption in patients with coronary artery disease.

Zusammenfassung

Ziel: Bei reversibler und irreversibler Myokardschädigung infolge Ischämie sind die Membranfunktionen der Zellen verändert. Um myokardialen Metabolismus freier Fettsäuren (FFA) und Durchblutung bei belastungsinduzierter Ischämie zu vergleichen, untersuchten wir zehn Patienten mit Koronarinsuffizienz, aber ohne vorangegangenen Myokardinfarkt. Methoden: Nach Injektion von ¹²³I-markierter Heptadekansäure (HDA) wurde eine Serie von SPECT-Messungen nach Belastung aufgenommen. Die myokardiale Perfusion wurde abgeschätzt durch die separat durchgeführte Thalliumverteilungsstudie nach Belastung. Fettsäurestoffwechsel, Thallium-Up-take und -Washout wurden für die anterioren, posterioren und septalen Segmente berechnet. Ergebnisse: Eine eingeschränktere FFA-Stoffwechselrate (–63 ±18%, ±1 SD) verglichen mit der Durchblutung (-–36 ±16%) steht im Zusammenhang mit dem Ausmaß der myokardialen Ischämie und abnormen Wandbewegungen. Schlussfolgerung: Für diese kleine Patientengruppe gilt, dass eine reduzierte FFA-Stoffwechselrate die spärliche Arbeitslast des unter Belastung stehenden Myokards andeutet als Folge eingeschränkten Sauerstoffverbrauchs bei Patienten mit Koronarinsuffizienz.

Keywords

Coronary artery disease - fatty acids - ischemia

Schlüsselwörter

Koronarinsuffizienz - Fettsäuremetabolismus - Ischämie

• References

• 1 Cavelier V, De Geeter F, Pansar I. et al. Effect of exercise induced hyperlactatemia on the biodistribution and metabolism of iodine-123-15-(p-iodophenyl)-3-R, S-methyl pentadecanoic acid in normal volunteers. Eur J Nucl Med 2000; 27: 33-40.
• 2 Corbett JR. Fatty acids for myocardial imaging. Semin Nucl Med 1999; 29: 237-58.
• 3 Everaert H, Vanhove C, Franken PR. Assessment of perfusion, function, and myocardial metabolism after infarction with a combination of low-dose dobutamine tetrofosmin gated SPECT perfusion scintigraphy and BMIPP SPECT imaging. J Nucl Cardiol 2000; 7: 29-36.
• 4 Feinendegen LE, Henrich MM, Kuikka JT. et al. Myocardial lipid turnover in dilated cardiomyopathy: a dual in vivo tracer approach. J Nucl Cardiol 1995; 2: 42-52.
• 5 Fukuchi K, Hasegawa S, Ito Y. et al. Detection of coronary artery disease by iodine-¹²³-labeled iodophenyl-9-methyl pentadecanoic acid SPECT: comparison with thallium-201 and iodine-123 BMIPP SPECT. Ann Nucl Med 2000; 14: 11-6.
• 6 Hosokawa R, Nohara R, Fujibayashi Y. et al. Myocardial metabolism of ¹²³I-BMIPP in a canine model with ischemia: implications of perfusion-metabolism mismatch on SPECT images in patients with ischemic heart disease. J Nucl Med 1999; 40: 471-8.
• 7 Kaul S, Chesler DA, Pohost GM. et al. Influence of peak exercise heart rate on normal thallium-201 myocardial clearance. J Nucl Med 1986; 27: 26-30.
• 8 Knapp Jr FF, Kropp J. Iodine-¹²³-labelled fatty acids for myocardial single-photon emission tomography: current status and future perspectives. Eur J Nucl Med 1995; 22: 361-81.
• 9 Marie PY, Angioi M, Danchin N. et al. Assessment of myocardial viability in patients with previous myocardial infarction by using single-photon emission computed tomography with a new metabolic tracer: [¹²³I]-16-iodo-3-methylhexadecanoic acid (MIHA). Comparison with the rest-reinjection thallium-201 technique. J Am Coll Cardiol 1997; 30: 1241-8.
• 10 Opie LH. The Heart. Physiology, from cell to circulation. Philadelphia: Lippincott-Raven Publishers; 1998
• 11 Sloof GW, Visser FC, Teerlink T. et al. Incorporation of radioiodinated fatty acids into cardiac phospholipids of normoxic canine myocardium. Mol Cell Biochem 1992; 116: 79-87.
• 12 Stremmel W. Fatty acid uptake in the heart: update 1998. Nuklearmedizin 1998; 37: S1-4.
• 13 Taki J, Matsunari I, Nakajima K. et al. BMIPP compared with thallium redistribution. Int J Card Imaging 1999; 15: 49-59.
• 14 Tamaki N, Kuge Y, Tsukamoto E. Clinical roles of perfusion and metabolic imaging. J Cardiol 2001; 37 (Suppl. 01) 57-64. .
• 15 Turpeinen AK, Kuikka JT, Vanninen E. et al. Abnormal myocardial kinetics of ¹²³I-heptadecanoic acid in subjects with impaired glucose tolerance. Diabetologia 1997; 40: 541-9.
• 16 Van der Wall EE, Heidendal GA, den Hollander W. et al. Metabolic myocardial imaging with ¹²³I-labeled heptadecanoic acid in patients with angina pectoris. Eur J Nucl Med 1981; 6: 391-6.
• 17 Verani MS, Willerson JT. Impact of nuclear cardiac imaging on the present and future practice of cardiology. Eur J Nucl Med 2000; 27: S21-6.
• 18 Yamagishi H, Akioka K, Takagi M. et al. Relationship between the kinetics of thallium-201 in myocardial scintigraphy and myocardial metabolism in patients with acute myocardial infarction. Heart 1998; 80: 28-34.
• 19 Yang JY, Ruiz M, Calnon DA. et al. Assessment of myocardial viability using I-labeled iodophenylpentadecanoic acid at sustained low flow or after acute infarction and reperfusion. J Nucl Med 1999; 40: 821-8.