Cardiac resynchronisation therapy - Effects on myocardial perfusion at rest, after vasodilation and oxygen consumption

Aim: Cardiac resynchronisation therapy (CRT) has been shown to improve haemodynamics and clinical symptoms in heart failure patients. The present study evaluated the effects of a 4-month CRT on myocardial blood flow (MBF) at rest, after vasodilation and on myocardial oxygen consumption (MVO2). Patients, Methods: We studied 16 patients with idiopathic dilated cardiomyopothy prior to and during CRT performed as biventricular pacing. Resting MBF and MVO2 were determined from an C-11-acetate PET study and vasodilator MBF from a N-13-ammonia study. Results: MBF at rest (0.55 +/- 0.10 ml/min/g), after vasodilation (1.20 +/- 0.45 ml/min/g), and MVO2 (0.082 +/- 0.014/min) did not change by mid-term CRT at a global level (0.57 +/- 0.11 ml/min/g; 1.32 +/- 0.49 ml/min/g; 0.085 +/- 0.018/min), whereas the rate pressure product (RPP) normalised MVO2 decreased from 0.104 +/- 0.024 to 0.086 +/- 0.018/min (p = 0.02). At baseline, the regional analysis revealed significantly higher values for all parameters in the lateral wall than for those in the other walls. Under CRT the regional differences between the resting parameters equalised and all parameters showed significant lower coefficients of variation. conclusion: Effects of mid-term CRT on resting MBF, vosodilator MBF and MVO2 Occur at 0 regional level. The resynchronisation is associated with a more homogenous distribution pattern of these parameters among the myocardial walls. Substantial alterations to global MBF at rest, after vasodilation or to MVO2 are not detectable. Regarding the RPP normalised MVO2, there is evidence of improved ventriculor efficiency through CRT.