Negative predictive value of normal adenosine-stress cardiac MRI in the assessment of coronary artery disease and correlation with semiquantitative perfusion analysis.

PURPOSE: To prospectively determine the negative predictive value of normal adenosine stress cardiac MR (CMR) in routine patients referred for evaluation of coronary artery disease (CAD), predominantly with intermediate to high pretest risk. MATERIALS AND METHODS: Consecutive patients referred for coronary angiography were examined in a 1.5 Tesla whole-body scanner before catheterization. A total of 158 patients with normal CMR on qualitative assessment were included, and semiquantitative perfusion analysis was performed. Significant CAD was regarded as luminal narrowing of >or=70% in coronary angiography. RESULTS: In the 158 study patients, negative predictive value of normal adenosine-stress CMR for significant CAD was 96.2% (for stenosis >or=90%: 98.1%). True-negative and false-negative patients were comparable regarding clinical presentation, risk factors, and CMR findings. Semiquantitative perfusion analysis gave significantly prolonged arrival time index and peak time index in the false-negative group. Using cutoff values >1.8 for arrival time index or >1.2 for peak time index, the CMR negative predictive value increased to 98.7% (for stenosis >or=90%: to 100%). CONCLUSION: The very high negative predictive value for CAD supports CMR-based decision making for the indication to coronary angiography. Semiquantitative perfusion analysis seems promising to identify the small group of CAD patients not detectable by qualitative CMR assessment.

Prognostic value of normal adenosine-stress cardiac magnetic resonance imaging.

We investigated the prognostic value of normal adenosine stress cardiac magnetic resonance (CMR) in suspected coronary artery disease (CAD). Prospectively enrolled in the study were 218 patients with suspected CAD, no stress hypoperfusion, and no delayed enhancement in CMR, and consecutively deferred coronary angiography. The primary end point was a 12-month rate of major adverse cardiac events (MACE; cardiovascular mortality, myocardial infarction, revascularization, hospitalization due to cardiovascular event). CMR indication was symptomatic angina (Canadian Cardiovascular Society II in 42% and III in 7%) or evaluation of myocardial ischemia in patients with arrhythmia, syncope, and/or equivocal stress tests and cardiovascular risk factors (51%). As the main result, the 12-month MACE rate was 2/218 (1 stent implantation, 1 bypass surgery) and CMR negative predictive value 99.1%. There was no cardiac death or myocardial infarction. In conclusion, normal adenosine stress CMR predicts a very low MACE rate and an excellent 1-year prognosis in patients with suspected CAD. Our results provide clinical reassurance that patients at risk for CAD-associated MACE were not missed by CMR. Hence, CMR may serve as a reliable noninvasive gatekeeper to reduce the number of redundant coronary angiographies.

Angiographic correlations of patients with small vessel disease diagnosed by adenosine-stress cardiac magnetic resonance imaging.

Cardiac magnetic resonance imaging (CMR) with adenosine-stress myocardial perfusion is gaining importance for the detection and quantification of coronary artery disease (CAD). However, there is little knowledge about patients with CMR-detected ischemia, but having no relevant stenosis as seen on coronary angiography (CA). The aims of our study were to characterize these patients by CMR and CA and evaluate correlations and potential reasons for the ischemic findings. 73 patients with an indication for CA were first scanned on a 1.5T whole-body CMR-scanner including adenosine-stress first-pass perfusion. The images were analyzed by two independent investigators for myocardial perfusion which was classified as subendocardial ischemia (n = 22), no perfusion deficit (n = 27, control 1), or more than subendocardial ischemia (n = 24, control 2). All patients underwent CA, and a highly significant correlation between the classification of CMR perfusion deficit and the degree of coronary luminal narrowing was found. For quantification of coronary blood flow, corrected Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) was evaluated for the left anterior descending (LAD), circumflex (LCX) and right coronary artery (RCA). The main result was that corrected TFC in all coronaries was significantly increased in study patients compared to both control 1 and to control 2 patients. Study patients had hypertension or diabetes more often than control 1 patients. In conclusion, patients with CMR detected subendocardial ischemia have prolonged coronary blood flow. In connection with normal resting flow values in CAD, this supports the hypothesis of underlying coronary microvascular impairment. CMR stress perfusion differentiates non-invasively between this entity and relevant CAD.

Influence of small caliber coronary arteries on the diagnostic accuracy of adenosine stress cardiac magnetic resonance imaging.

BACKGROUND AND AIMS: Positive predictive value (PPV) of adenosine stress cardiac magnetic resonance (CMR) for coronary artery disease (CAD) is unsatisfactory. We investigated the impact of coronary caliber variability on this limitation in CMR performance. METHODS AND RESULTS: 206 consecutive patients with myocardial ischemia during CMR and subsequent coronary angiography (CA) were studied. Patients were examined in a 1.5-T scanner. After adenosine infusion, myocardial first-pass sequence using gadolinium-based contrast agent was performed and compared with rest perfusion. CAD was invasively confirmed in 165 [true positive (TP); PPV, 80.1%] and ruled out in 41 patients [false positive (FP)]. TP and FP were comparable for pre-test risk and CMR findings. We found a significant association between FP CMR and the presence of a small caliber coronary vessel (proximal diameter < one standard deviation below the mean) supplying the area of ischemia (chi-square 42.6, p < 0.0001). A small caliber artery ipsilateral to the ischemic region was a predictive parameter for FP versus TP discrimination (ROC area, 0.84 ± 0.04 vs. 0.59 ± 0.05; p < 0.0001). Further increment in diagnostic accuracy was achieved by including proximal ipsilateral/contralateral coronary diameter ratios (ROC area, 0.90 ± 0.03; p < 0.03). CONCLUSIONS: Small caliber coronary arteries found as normal variations in right-dominant or left-dominant circulation may account for hypoperfusion in the absence of coronary stenosis and thus may cause FP adenosine stress CMR results. Non-invasive assessment of proximal coronary diameters in the vessel supplying the area of ischemia could reduce FP rates, raise the diagnostic accuracy of CMR for CAD and minimize subsequent superfluous CA.

Clinical implication of adenosine-stress cardiac magnetic resonance imaging as potential gatekeeper prior to invasive examination in patients with AHA/ACC class II indication for coronary angiography.

BACKGROUND: Real world cardiology is faced with a low diagnostic yield of coronary angiography (CXA) in patients presenting with ACC/AHA class II CXA indication. Our aim was to analyze the clinical implication of a Cardiac MR (CMR) protocol including adenosine stress perfusion in this patient population. We examined whether CMR could enhance appropriate CXA indication and thus reduce the rate of pure diagnostic CXA. In addition, we compared the relative impact of CMR exam components (perfusion, function and viability assessment) in achieving this target. METHODS: 176 patients were referred for CXA with class II indication. 171 underwent complete additional CMR exam in a 1.5-T whole body CMR-scanner for myocardial function, ischemia and viability prior to CXA. The routine protocol for assessment of CAD consisted of functional imaging (long and short axes), adenosine stress- and rest-perfusion in short axis orientation and "late enhancement" imaging in long and short axes. Images were analyzed by two independent and blinded investigators. Interobserver differences were resolved by a third reader. RESULTS: There was a high association between CMR results and subsequent invasive findings (chi square for CMR perfusion deficit and stenosis >70% in CXA: 113.7, p<0.0001). 109 (63.7%) of our patients had relevant perfusion deficits as seen by CMR and matching coronary artery stenosis >70%. Four (2.3%) patients had false negative CMR findings. In 58 patients (33.9%) no relevant coronary artery stenosis could be observed, correctly predicted by CMR in 48 cases; in 10 (5.8%) patients CMR provided false positive results. Sensitivity of CMR to detect relevant CAD (>70% luminal narrowing) was 0.96, specificity 0.83, positive predictive value 0.92 and negative predictive value 0.92. Of the CMR components, perfusion deficit was the strongest independent predictor (odds ratio 132.3, p < 0.0001). CONCLUSION: In a great number of patients being referred to cath lab with ACC/AHA class II indication for CXA, CMR provides a high accuracy for decision making regarding appropriateness of the invasive exam. CMR prior to CXA could substantially reduce pure diagnostic coronary angiographies in patients with intermediate probability for CAD, in our patient-cohort from approximately 34% to 6%. Further studies are warranted to identify rare false negative CMR results.