Background: Changes in myocardial blood flow (MBF) and coronary flow reserve (CFR) are independent prognostic risk factors in idiopathic dilated cardiomyopathy (DCM). The aim of this study was to assess the impact of left ventricular unloading using left ventricular assist device (LVAD) combination therapy on resting MBF and CFR in patients with end-stage heart disease.
Methods: We studied 11 patients with deteriorating end-stage DCM (New York Heart Association Class 4) treated with LVAD support combined with pharmacologic therapy in a recovery program. Absolute MBF was measured using oxygen-15-labeled water (H(2)(15)O) positron emission tomography (PET) at rest during LVAD support and 15 minutes after the LVAD was switched off. Data were corrected for rate pressure product (RPP) when appropriate. Hyperemic MBF (intravenous adenosine, 140 mug/kg . min) was also measured in 6 patients with the LVAD switched off. CFR was calculated as the ratio MBF adenosine/MBF LVAD off (corrected). Data are expressed as mean +/- SD.
Results: At 317 +/- 193 days after device implantation, resting MBF was 0.95 +/- 0.29 (LVAD on) and 1.46 +/- 0.62 (LVAD off, corrected) ml/min . g (p = 0.01). MBF (LVAD on) was comparable with that of 11 age- and gender-matched normal controls (1.09 +/- 0.22 ml/min . g). CFR in the LVAD group was 1.49 +/- 0.99 compared with 3.56 +/- 1.42 in normal controls (p < 0.01).
Conclusions: During LVAD support, resting MBF (LVAD on) was comparable to MBF in normal controls and increased when the LVAD was switched off. However, CFR was significantly impaired, even though all patients studied showed varying degrees of myocardial recovery. The implications of these findings, particularly in the long term, require further study.