Reverse Perfusion-Metabolism Mismatch Predicts Good Prognosis in Patients Undergoing Cardiac Resynchronization Therapy A Pilot Study

Abstract

t is now accepted that cardiac resynchronization therapy (CRT) improves cardiac function in patients with heart failure, and thus reduces morbidity and mortality. 1,2 However, cardiac function does not improve in all patients who undergo CRT. Some studies have revealed the predictive ability of the response to CRT. 3,4 Patients with left ventricular (LV) systolic dysfunction and dilatation frequently have ventricular conduction delay, such as left bundle branch block (LBBB), which is associated with delayed contraction of the lateral LV wall, causing early contraction of the septum, resulting in paradoxical movement. The abnormal activation sequence induced by spontaneous LBBB 5,6 or by right ventricular (RV) pacing-induced LBBB influences both the perfusion and glucose metabolism of the septum. 7,8 Simultaneous perfusion imaging with a tracer, such as technetium metoxy-isobutyl isonitrile (Tc-MIBI) or NH3, and fluorodeoxyglucose (FDG)-positron emission tomography (PET) has been used to identify myocardial viability and high-risk patients who are likely to benefit from revascularization therapy. Correct interpretation of the patterns of flow and metabolism, such as match, mismatch and reversed mismatch, is important. A mismatch pattern is observed in ischemic, hibernating but viable myocardium, 9 whereas a reverse mismatch pattern is often observed in patients with a recent myocardial infarction, 10 chronic stable coronary artery disease or LBBB. It was recently demonstrated that a reverse mismatch pattern is a sign of reversible myocardial dysfunction. 11,12 Both spontaneous and induced LBBB show a reverse mismatch pattern in the septal myocardium, 7,8 but the significance of this pattern as a predictor of prognosis in patients who subsequently undergo CRT is unknown. In this pilot study we used FDG-PET and metoxy-isobutyl isonitrile (MIBI)-single photon emission computed tomography (SPECT) to investigate whether the patterns of flow and glucose metabolism were related to prognosis in patients who underwent CRT. Background Cardiac resynchronization therapy (CRT) improves glucose metabolism in the septum of patients with heart failure, so in the present study the predictive value of combined fluorodeoxyglucose (FDG)-positron emission tomography (PET) and metoxy-isobutyl isonitrile (MIBI)-single photon emission computed tomography (SPECT) for the prognosis of patients undergoing CRT was investigated. Methods and ResultsFourteen patients (70.3±8.2 years) who underwent FDG-PET and MIBI-SPECT before implantation of a biventricular pacemaker were enrolled. The total number of matches, mismatches, reverse mismatches, summed difference score (SDS: sum total of FDG -MIBI scores) and SDS per segment (%SDS) in each of 5 areas of myocardium (septum, anterior, lateral, inferior area, apex) was calculated and compared between the survival groups (all survival: survival group; survival without ischemic heart disease (IHD): non-IHD survival group) and non-survival group. Both the number of reverse mismatch segments and the %SD...

Heterogeneous Reduction of Myocardial Oxidative Metabolism in Patients With Ischemic and Dilated Cardiomyopathy Using C-11 Acetate PET

“…[30][31][32] LBBB is known to impair LV mechanical function and is an important predictor of cardiac mortality in patients with HF caused by DCM. 10,33 Previous studies found that perfusion and glucose metabolism were reduced in cases with LBBB, [34][35][36][37][38][39][40][41][42] and the extent of scarring correlates with QRS duration. 29 Our data show reduced septal Kmono values in the comparison of the lateral walls in patients with DCM and LBBB, and the presence of LBBB appeared to be independent of the heterogeneous metabolic changes.…”

Identification of the Right Ventricular Pacing Site for Cardiac Resynchronization Therapy (CRT) Guided by Electroanatomical Mapping (CARTO)

“…11 As for the latter, several recent reports have suggested that selection based on the direct assessment of mechanical dyssynchrony by tissue-Doppler echocardiography is a potentially useful tool to increase response rate for CRT. [12][13][14][15][16][17] As for the optimal LV pacing site, the PATH-CHF II study has demonstrated that pacing at LV free wall sites consistently produces better short-term hemodynamic responses than does pacing at LV anterior sites. 4,5 Furthermore, Auricchio et al demonstrated that the functional block line of LV, as determined by CARTO and non-contact mapping, varied among individual patients with left bundle branch block (LBBB) (ie, anterior, lateral, or inferior aspects), and suggested that the site of delay above the functional block line was the optimal pacing site.…”

Multifocal, Persistent Cardiac Uptake of [18-F]-Fluoro-Deoxy-Glucose Detected by Positron Emission Tomography in Patients With Acute Myocardial Infarction

“…[16][17][18] In the present study, patients were fasting for at least 12 h before tracer injection. PET images were acquired in 2D mode with a static 10-min frame, starting 60 min after IV injection of 296-370 MBq (8-10 mCi) of [18-F]-FDG.…”