Difference in Myocardial Flow Reserve Between Patients With Dilated Cardiomyopathy and Those With Dilated Phase of Hypertrophic Cardiomyopathy

Muneo Ohba, Ryohei Hosokawa, Naoshige Kambara, Eiji Tadamura, Marcelo Mamede, Shigeto Kubo, Masaki Yamamuro, Masatoshi Fujita, Takeshi Kimura, Ryuji Nohara, Toru Kita
2007 Circulation Journal  
yocardial flow reserve (MFR) is defined as the ratio of maximal to basal myocardial blood flow (MBF), and it is related to the severity of coronary artery stenosis. 1-8 Therefore, the MFR value is clinically useful for decision-making and the strategy of coronary intervention. Recent studies have shown that MFR is impaired by age 9 and coronary risk factors, such as smoking, 10 hyperlipidemia (HPL), 11,12 diabetes mellitus (DM), 13 and hypertension (HTN), 14 even in the absence of coronary
more » ... sis. The MFR can be accurately measured invasively and noninvasively. Clinical evaluation of MFR using positron emission tomography (PET) is a safe and repeatable method to use for patients without coronary artery dis-ease, 15-17 compared with invasive methods such as Doppler flow-wire. 18 Several studies have reported that MFR is impaired, together with the poor prognosis, in both patients with dilated cardiomyopathy (DCM) 19-24 and those with hypertrophic cardiomyopathy (HCM). [25] [26] [27] [28] [29] [30] In particular, the prognosis is poorer for patients with the dilated phase of HCM (DHCM), who have systolic dysfunction and left ventricular (LV) remodeling, than in those with DCM. However, the pathophysiological differences between these 2 types of cardiomyopathies remain unclear. The purpose of this study was to compare MBF, MFR and coronary vascular resistance (CVR) between patients with DCM and those with DHCM, using 15 O-labeled water PET, 8,31-33 which is similar to 13 N ammonia PET. 34 Methods Study Population We studied 30 patients with cardiomyopathies (23 men, 7 women; mean age 60.9±12.3 years) who were admitted to the Department of Cardiovascular Medicine, Kyoto University Hospital because of worsening heart failure. The group included 23 patients with DCM (Group A) and 7 patients with DHCM (Group B). After admission, the patients were treated with conventional medical therapy, and Circ J 2007; 71: 884 -890 Background The clinical features of patients with the dilated phase of hypertrophic cardiomyopathy (DHCM) may resemble those of patients with dilated cardiomyopathy (DCM); that is, systolic dysfunction and left ventricular dilatation. Myocardial flow reserve (MFR) is impaired in patients with nonischemic cardiomyopathy, and the reduced MFR may be related to poor prognosis. Several studies report that the mortality rate for patients with DHCM is higher than for DCM, but the difference between these 2 cardiomyopathies is still unclear. The purpose of this study was to assess the MFR of these 2 cardiomyopathies, using 15 O-water positron emission tomography (PET) to elucidate their differences. Methods and Results In total 30 patients were investigated: 23 with DCM (Group A) and 7 with DHCM (Group B). All those who were in a stable condition underwent cardiac catheterization. Myocardial blood flow (MBF) at rest and under ATP infusion was measured by 15 O-water PET, and the MFR was calculated. There were no significant differences in the hemodynamics of the 2 groups. The mean MFR in DHCM was significantly lower than that in DCM (1.49±0.31 vs 2.62±1.08; p=0.042), whereas MBF at rest did not differ (DCM vs DHCM: 0.66±0.20 vs 0.49±0.05 ml·min -1 ·g -1 ; NS). The MFR in both Group A and B was significantly decreased compared with the normal controls (MFR in normal controls: 5.15±1.64, p=0.00015, 0.00013, respectively). Conclusions These results suggest that impaired vasodilatation (ie, dysfunction of the microcirculation) is more severe in patients with DHCM than in patients with DCM, even though patients' characteristics and hemodynamics do not differ. (Circ J 2007; 71: 884 -890)
doi:10.1253/circj.71.884 pmid:17526985 fatcat:afsxftkz3raubl6t37wxhvvnmq