Background — Depressed myocardial blood flow (MBF) has been reported in dilated cardiomyopathy. The aim of this study was to investigate whether MBF impairment is an independent predictor of prognosis in patients with idiopathic left ventricular (LV) dysfunction. Methods and Results — Sixty-seven patients (52 male, mean age 52±12 years) with different degrees of idiopathic LV systolic dysfunction (average LV ejection fraction, 0.34±0.10; range, 0.07 to 0.49) were prospectively enrolled. Thirty-four subjects (51%) had no history of heart failure symptoms at enrollment (NYHA class I). All patients underwent clinical and functional evaluation and a PET study to measure absolute MBF at rest and after intravenous dipyridamole. During a mean follow-up of 45±37 months, 24 patients had major cardiac events, including cardiac death in 8 and development or progression of heart failure in 16 patients. Multivariate regression analysis (Cox proportional hazards model) revealed heart rate (χ ² 11.06, P <0.001), LV end-diastolic dimension (χ ² 11.73, P <0.001), and dipyridamole MBF (χ ² 11.04, P <0.001) as independent predictors of subsequent cardiac events. Dipyridamole MBF ≤1.36 mL · min ⁻¹ · g ⁻¹ was associated with an increase in the relative risk of death, development, or progression of heart failure of 3.5 times over other more common clinical and functional variables. Conclusions — The present study demonstrates that severely depressed MBF is a predictor of poor prognosis in patients with idiopathic LV dysfunction independently of the degree of LV functional impairment and of the presence of overt heart failure.

Background—: The choice of imaging techniques in patients with suspected coronary artery disease (CAD) varies between countries, regions, and hospitals. This prospective, multicenter, comparative effectiveness study was designed to assess the relative accuracy of commonly used imaging techniques for identifying patients with significant CAD. Methods and Results—: A total of 475 patients with stable chest pain and intermediate likelihood of CAD underwent coronary computed tomographic angiography and stress myocardial perfusion imaging by single photon emission computed tomography or positron emission tomography, and ventricular wall motion imaging by stress echocardiography or cardiac magnetic resonance. If ≥1 test was abnormal, patients underwent invasive coronary angiography. Significant CAD was defined by invasive coronary angiography as >50% stenosis of the left main stem, >70% stenosis in a major coronary vessel, or 30% to 70% stenosis with fractional flow reserve ≤0.8. Significant CAD was present in 29% of patients. In a patient-based analysis, coronary computed tomographic angiography had the highest diagnostic accuracy, the area under the receiver operating characteristics curve being 0.91 (95% confidence interval, 0.88–0.94), sensitivity being 91%, and specificity being 92%. Myocardial perfusion imaging had good diagnostic accuracy (area under the curve, 0.74; confidence interval, 0.69–0.78), sensitivity 74%, and specificity 73%. Wall motion imaging had similar accuracy (area under the curve, 0.70; confidence interval, 0.65–0.75) but lower sensitivity (49%, P <0.001) and higher specificity (92%, P <0.001). The diagnostic accuracy of myocardial perfusion imaging and wall motion imaging were lower than that of coronary computed tomographic angiography ( P <0.001). Conclusions—: In a multicenter European population of patients with stable chest pain and low prevalence of CAD, coronary computed tomographic angiography is more accurate than noninvasive functional testing for detecting significant CAD defined invasively. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00979199.

Under resting conditions, the failing heart shifts fuel use toward greater glucose and lower free fatty acid (FFA) oxidation. We hypothesized that chronic metabolic abnormalities in patients with dilated cardiomyopathy (DCM) are associated with the absence of the normal increase in myocardial glucose uptake and maintenance of cardiac mechanical efficiency in response to pacing stress. In 10 DCM patients and 6 control subjects, we measured coronary flow by intravascular ultrasonometry and sampled arterial and coronary sinus blood. Myocardial metabolism was determined at baseline, during atrial pacing at 130 beats/min, and at 15 min of recovery by infusion of [³H]oleate and [¹³C]lactate and measurement of transmyocardial arteriovenous differences of oxygen and metabolites. At baseline, DCM patients showed depressed coronary flow, reduced uptake and oxidation of FFA, and preferential utilization of carbohydrates. During pacing, glucose uptake increased by 106% in control subjects but did not change from baseline in DCM patients. Lactate release increased by 122% in DCM patients but not in control subjects. Cardiac mechanical efficiency in DCM patients was not different compared with control subjects at baseline but was 34% lower during stress. Fatty acid uptake and oxidation did not change with pacing in either group. Our results show that in DCM there is preferential utilization of carbohydrates, which is associated with reduced flow and oxygen consumption at rest and an impaired ability to increase glucose uptake during stress. These metabolic abnormalities might contribute to progressive cardiac deterioration and represent a target for therapeutic strategies aimed at modulating cardiac substrate utilization.

Background Myocardial blood flow (MBF) impairment has been documented in advanced dilated cardiomyopathy (DCM) in which hemodynamic factors, secondary to severe ventricular dysfunction, may limit myocardial perfusion. To assess whether MBF impairment in DCM may also be present independent of hemodynamic factors, the present study was designed to quantify myocardial perfusion in patients with mild disease without overt heart failure. Methods and Results Absolute regional MBF (milliliters per minute per gram) was measured by positron emission tomography and ¹³ N-ammonia in resting conditions, during pacing-induced tachycardia, and after dipyridamole infusion (0.56 mg/kg over 4 minutes) in 22 DCM patients and in 13 healthy subjects. Patients were in New York Heart Association functional class I-II and showed depressed left ventricular (LV) ejection fraction by radionuclide angiography (35±8%; range, 21% to 48%), normal coronary angiography, and normal or moderately increased LV end-diastolic pressure (9.2±5.5 mm Hg; range, 2 to 20 mm Hg). There were no differences in arterial blood pressure, heart rate, and rate-pressure product between patients and control subjects in the three study conditions. Compared with control subjects, DCM patients had lower mean MBF at rest (0.80±0.25 versus 1.08±0.20 mL · min ⁻¹ · g ⁻¹ , P <.01), during atrial pacing tachycardia (1.21±0.59 versus 2.03±0.64 mL · min ⁻¹ · g ⁻¹ , P <.01), and after dipyridamole infusion (1.91±0.76 versus 3.78±0.86 mL · min ⁻¹ · g ⁻¹ , P <.01). LV MBF values were related to baseline LV end-diastolic pressure at rest ( r =−.57, P <.01) and during pacing ( r =−.67, P <.01) but not after dipyridamole infusion ( r =.19, P =.40). Five patients had LV end-diastolic pressure >12 mm Hg; in 4, myocardial perfusion was severely depressed both at baseline and in response to stress. Conclusions In patients with DCM without overt heart failure, myocardial perfusion is impaired both at rest and in response to vasodilating stimuli. The abnormalities in vasodilating capability can be present despite normal hemodynamics; progression of the disease is associated with more depressed myocardial perfusion.

Arrhythmogenic cardiomyopathy (AC) is a progressive disease with high risk of life-threatening ventricular arrhythmias. A genetic mutation is found in up to 50–60% of probands, mostly affecting desmosomal genes. Diagnosis of AC is made by a combination of data from different modalities including imaging, electrocardiogram, Holter monitoring, family history, genetic testing, and tissue properties. Being a progressive cardiomyopathy, repeated cardiac imaging is needed in AC patients. Repeated imaging is important also for risk assessment of ventricular arrhythmias. This expert consensus document gives clinical recommendations for how to use multi-modality imaging in the different aspects of AC disease, including diagnosis, family screening, follow-up, risk assessment, and differential diagnosis.