recently , a new method for assessing the functional significance of coronary computed tomography angiography ( ccta ) has become available .
this method uses patient - specific anatomic data from ccta , mathematic modeling of coronary physiology , and computation of coronary pressure and blood flow utilizing computational fluid dynamics to provide a noninvasive measure of fractional flow reserve ( ffrct ) , which can identify ischemia - producing stenoses .
the present case demonstrates the potential role of this new method as a gatekeeper to the catheterization laboratory .
a 52-year - old male was referred for evaluation of atypical chest discomfort after strenuous exercise and occasional stabbing pain in the left thorax not associated with physical activity .
the patient exercised daily and he had competed in 39 marathons without any chest symptoms .
total cholesterol and low density lipoprotein were 7.1 and 5.5 mmol / l , respectively . due to the uncharacteristic nature of the patient 's symptoms ,
the calcium score was 140 and ccta revealed calcified and noncalcified coronary atherosclerosis with a mixed , stenotic plaque in the mid left anterior descending coronary artery ( lad ) [ figure 1 ] .
myocardial perfusion and coronary flow reserve were normal during adequate stress response to adenosine ( 140 g / kg / min ) [ figure 2 ] .
. coronary computed tomography angiography curved planar reformation image of the mid left anterior descending coronary artery .
static rubidium-82 perfusion images ( 17 segment polar maps ) demonstrates no difference between stress ( top ) and rest perfusion ( bottom ) .
total acquisition time was 270 s. one year later , following strenuous running , the patient sustained a cardiac arrest .
cardiopulmonary resuscitation was started immediately with successful electrical cardioversion of ventricular fibrillation and return of spontaneous circulation 6 min after the alarm .
ten days later , transthoracic echocardiography showed left ventricular ejection fraction of 4045% with apical hypokinesis .
53-year - old male presenting with severe chest pain and cardiac arrest , which was successfully treated with resuscitation and cardioversion .
12-lead electrocardiogram shows massive st - elevation consistent with anterior st - elevation myocardial infarction .
53-year - old male presenting with severe chest pain and cardiac arrest , which was successfully treated with resuscitation and cardioversion .
invasive angiography shows prestent image of left anterior descending coronary artery occlusion marked by the white arrow ( left side , angiography projection : 4 right anterior oblique and 24 cranial ) and poststent image of re - perfused left anterior descending coronary artery with the white arrow marking the point of previous occlusion ( right side , angiography projection : 6 right anterior oblique and 30 cranial ) . as a blind study
, we submitted the patient 's ccta data , which had been obtained one year earlier and had revealed a highly significant ischemia - producing lesion in the mid - lad , for ffrct analysis [ figure 5 ] .
ffrct analysis was performed at heartflow ( redwood city , ca , usa ) utilizing updated proprietary software .
computation of noninvasive ffrct from ccta image data requires a physiologic model of coronary blood flow .
the physiologic model is based on three underlying principles as described in detail by taylor et al .
, : ( i ) the total resting coronary blood flow can be quantified relative to the myocardial mass , ( ii ) the microcirculatory vascular resistance at rest is inversely proportional to the size of the coronary arteries supplying the myocardium , and ( iii ) the vasodilatory response of the coronary microcirculation to adenosine infusion can be predicted , allowing computational modeling of the maximal hyperemic state .
the integration of the model of coronary physiology to 3-dimensional computational models allows computation of coronary flow and pressure at each point in the coronary arteries under hyperemic conditions .
fractional flow reserve ( ffrct = 0.52 ) derived from coronary computed tomography images and based on a physiologic model of coronary blood flow using three principles : ( 1 ) the total resting coronary blood flow can be quantified relative to the myocardial mass , ( 2 ) the microcirculatory vascular resistance at rest is inversely proportional to the size of the supplying coronary arteries , and ( 3 ) the vasodilatory response of the coronary microcirculation to adenosine can be predicted , allowing computational modeling of maximal hyperemia .
the integration of the physiological model into 3-dimensional computational models allows computation of coronary flow and pressure under hyperemic conditions .
this case demonstrates the inherent limitations of assessing lesion - specific ischemia utilizing currently available noninvasive imaging modalities .
while ccta can reliably identify coronary stenoses , it can not assess their functional significance .
a coronary stenosis 50% detected by conventional angiography has a significantly lower diagnostic accuracy when compared with ffrct in detecting significant coronary artery disease as defined by ffr .
myocardial perfusion imaging can detect perfusion abnormalities , but can not assess the hemodynamic significance of individual coronary lesions .
moreover , myocardial perfusion imaging misclassifies up to 58% of ischemic myocardial territories when compared with ffr in multivessel disease .
the prospective , randomized fractional flow reserve versus angiography for multivessel evaluation ( fame 2 ) study has demonstrated reduced mortality and myocardial infarction from revascularization of lesions with ffr < 0.80 when compared with standard practice . one putative mechanism for this benefit is identification of stenoses at high risk for plaque rupture .
noninvasive ffrct values compare well with measured ffr , thus ffrct may play a major role for selection of patients for coronary angiography .
large - scale prospective studies comparing the effect of ffrct versus standard diagnostic evaluation are ongoing .
ffrct shows promise as a new method to identify lesion - specific ischemia noninvasively and , thus , ffrct may play a role in the selection of patients for coronary angiography .
 a physically active 52-year - old male with atypical chest pain was referred to our department . a coronary computed tomography angiography ( ccta ) showed a stenotic plaque in the mid left anterior descending coronary artery ( lad ) . 
 a rest  
 stress rubidium-82 myocardial perfusion was normal . 
 one year later the patient sustained a cardiac arrest and percutaneous coronary intervention of the mid - lad was successfully performed . 
 the original ccta data were submitted for noninvasive determination of fractional flow reserve ( ffrct ) revealing an ischemia - producing lesion in the mid - lad . 
 this case demonstrates the inherent limitations of assessing lesion - specific ischemia . 
 ffrct shows promise as a new method for future selection of patients for coronary angiography . 
INTRODUCTION
CASE REPORT
DISCUSSION
CONCLUSION