Feasibility of intracoronary nicorandil for inducing hyperemia on fractional flow reserve measurement: Comparison with intracoronary papaverine.

BACKGROUND: Adenosine and adenosine triphosphate (ATP) are widely used to induce hyperemia for fractional flow reserve (FFR) measurements. Caffeine attenuates their hyperemic effects, but not those of nicorandil and papaverine. No studies have systematically compared the hyperemic efficacies of nicorandil, papaverine, and ATP with and without caffeine abstention. METHODS: FFRs were measured using nicorandil 2 mg (FFRNC2), nicorandil 4 mg (FFRNC4), and papaverine (FFRPAP) in 40 patients (group 1), and using nicorandil 2 mg, ATP (FFRATP), ATP plus nicorandil (FFRATP+NC2), and papaverine in 20 patients with (group 2) and in 20 patients without caffeine abstention (group 3). RESULTS: In group 1, FFRNC2 and FFRNC4 did not differ (p = 0.321) and were higher than FFRPAP (p < 0.001 and p = 0.0026). Likewise, FFRNC2 was higher than FFRPAP in groups 2 (p = 0.049) and 3 (p < 0.010). In the whole group, Bland-Altman analysis showed a modest mean difference (0.015, p < 0.001) and narrow 95% limits of agreement (-0.025 and 0.056). FFRNC2 and FFRPAP strongly correlated (r = 0.975, p < 0.001). Compared with FFRPAP, FFRATP and FFRATP+NC2 did not differ in group 2 (p = 1.0 and p = 0.780), but they were higher (p = 0.002 and p = 0.02) in group 3. Adjunctive nicorandil did not decline FFR further in groups 2 (p = 0.942) and 3 (p = 0.294). CONCLUSIONS: Nicorandil 2 mg is a safe and practical alternative for patients who consume caffeine-containing products before the test or have contraindications for adenosine/ATP. Increasing the nicorandil dose to 4 mg or administering adjunctive nicorandil during ATP infusions does not offer any clinical advantages compared with administering nicorandil 2 mg alone.

Retrograde percutaneous coronary intervention for acute myocardial infarction following blunt chest trauma.

A 78-year-old man was admitted to the emergency department because of chest pain following blunt chest trauma. Chest X-ray revealed multiple rib fractures. However, electrocardiogram showed ST elevation in inferior leads suggesting acute myocardial infarction (AMI). Emergency coronary angiography revealed normal left coronary artery and occluded proximal right coronary artery. Thus, percutaneous coronary intervention (PCI) was performed immediately. Antegrade PCI was unsuccessful due to a very large false lumen, which was caused by a blunt trauma. However, retrograde guidewire (GW) manipulation was relatively easy to negotiate the occluded lesion. After GW externalization, we deployed two drug eluting stents for this lesion. To our knowledge, this is the first case of retrograde PCI that led to a successful reperfusion therapy for AMI following blunt chest trauma.

Temporal change of enhancement after gadolinium injection on contrast-enhanced CMR in reperfused acute myocardial infarction.

BACKGROUND: A recent report demonstrated that early enhancement on contrast-enhanced cardiac magnetic resonance (CE-CMR) correlated with myocardial edema detected by T2-weighted CMR in reperfused acute myocardial infarction (AMI). However, the time at which the enhancement in salvaged myocardium disappears is yet to be determined. We aimed to examine the time course of the enhancement with the use of different quantification techniques and to compare the extent of enhancement with the myocardial edema. METHODS AND RESULTS: CE-CMR was performed at 2-20 min after gadolinium administration in 32 AMI patients. The extent of enhancement (% myocardium) was quantified by manual delineation and the threshold methods of 2-5 SDs above remote myocardium. In subendocardial infarct, the enhancement was greatest at 2 min regardless of the quantification techniques and decreased with time, particularly in the first 6 min. In transmural infarct, the change in the size of enhancement was modest although the time course of enhancement varied according to the quantification techniques. The sizes of enhancement were not significantly different between 15 and 20 min regardless of the techniques and infarct transmurality. The best agreement with myocardial edema was found at 2 min with average differences of 0.5% and -1.2% and limits of agreement of ±20.2% and ±21.2% for the manual and 2-SD techniques, respectively. CONCLUSIONS: The optimal timing for delineation of salvaged myocardium on CE-CMR is at 2min when the manual or 2-SD technique was employed. Imaging needs to be completed in a short time (ideally within a minute) because of rapid reduction of enhancement in salvaged myocardium.

Effect of caffeine on intravenous adenosine-induced hyperemia in fractional flow reserve measurement.

BACKGROUND: The interaction between caffeine and adenosine is still a matter of debate. AIMS: We examined whether caffeine attenuated intravenous adenosine-induced hyperemia in the measurement of fractional flow reserve (FFR) and whether an increased dose of adenosine overcame the caffeine antagonism. METHODS: FFR was measured using different adenosine doses (140, 175, and 210 µg/kg/min) and papaverine as a reference standard in patients with intermediate coronary stenoses, who refrained from caffeine for >24 h (no-caffeine group; n = 14) and those who consumed caffeine (caffeine group; n = 28). RESULTS: The median caffeine level in the caffeine group was 2.9 mg/L (interquartile range, 1.8-4.6 mg/L). In the no-caffeine group, FFR with adenosine did not decrease above the dose of 140 µg/kg/min (0.769, 0.771, and 0.770 at 140, 175, and 210 µg/kg/min, respectively) and was not significantly different from that with papaverine (0.765). In the caffeine group, adenosine overestimated FFR (140 µg/kg/min: 0.813, P<.001; 175 µg/kg/min: 0.806, P<.01; 210 µg/kg/min: 0.794, P=.01) compared with papaverine (0.779). The difference in FFR between papaverine and 140 µg/kg/min dose of adenosine was significantly greater in the caffeine group than in the no-caffeine group (0.034 vs 0.004; P<.05). CONCLUSION: Caffeine attenuates intravenous adenosine-induced hyperemia in FFR measurement. Even increased adenosine doses up to 210 µg/kg/min cannot fully surmount the antagonism.

Peri-infarct zone on early contrast-enhanced CMR imaging in patients with acute myocardial infarction.

OBJECTIVES: The aims of this study were to evaluate hyperenhanced regions on contrast-enhanced cardiovascular magnetic resonance (CE-CMR) imaging in patients with acute myocardial infarction (AMI) between early contrast-enhanced cardiovascular magnetic resonance (ECE) (2 min) and late contrast-enhanced cardiovascular magnetic resonance (LCE) (10 to 15 min) after gadolinium administration, and to compare the CE-CMR images with area at risk (AAR) derived from T2-weighted (T2W) CMR. BACKGROUND: Although CE-CMR imaging can demarcate the infarcted myocardium, the value of hyperenhancement in AMI is still in dispute. The size of hyperenhanced regions may vary with time, and overestimation can be often observed with early acquisition. METHODS: Thirty-four patients with successfully reperfused AMI underwent CMR within 4 days after the event. Myocardial regions as percentage of left ventricular (LV) myocardium were quantified on CE and T2W images. Relative peri-infarct zone was calculated as the difference in hyperenhanced regions between ECE and LCE, normalized to the individual infarct size. RESULTS: Both ECE and LCE images revealed hyperenhancement in the territory of the infarct-related artery in all patients. The hyperenhanced region on ECE extended transmurally and was consistently larger than that on LCE (39 ± 12% vs. 27 ± 12% of LV myocardium, p<0.001). The relative peri-infarct zone was inversely correlated with the transmurality of infarction (r=-0.59, p<0.001) and the time from symptom to reperfusion (r=-0.46, p<0.01). The hyperenhanced region on ECE was correlated with the T2W CMR-derived AAR (r=0.86, p<0.001) with the average difference of -0.8% and the limits of agreement of ±11.9%. CONCLUSIONS: ECE depicts ischemically injured but salvaged myocardium, as well as infarcted myocardium in patients with AMI. The myocardium at risk and infarcted myocardium after reperfusion can be retrospectively assessed by the combination of ECE and LCE.

Late gadolinium-enhanced cardiovascular MRI at end-systole: feasibility study.

OBJECTIVE: The purpose of this article is to evaluate the image quality and infarct size of segmented late gadolinium-enhanced cardiovascular MRI at end-systole, compared with middiastole, in patients with sinus rhythm (SR) and to compare the image quality of end-systole images in patients with atrial fibrillation (AFib) to that of end-systole and middiastole images in patients with SR. SUBJECTS AND METHODS: Study patients (n = 121) were distributed according to heart rate and rhythm: SR with low heart rate (≤ 65 beats/minute), SR with intermediate heart rate (66-75 beats/minute), SR with high heart rate (≥ 76 beats/minute), and AFib. Image quality was graded on a 5-point scale, where 4 equals optimal and 0 equals not assessable. Global infarct size (percentage of left ventricle [LV] myocardium) in patients with SR with myocardial infarction was quantified using a visual quantitative approach with a 5-point scale and a semiautomatic method. RESULTS: End-systole imaging had higher image quality than did middiastole imaging for patients with SR with high heart rate, whereas middiastole imaging had higher image quality than did end-systole imaging for patients with SR with low heart rate (p < 0.05 for patients with SR with low heart rate, p = 0.60 for patients with SR with intermediate heart rate, and p = 0.001 for patients with SR with high heart rate). The quality of end-systole imaging in patients with AFib was not significantly different from that in patients with SR (p = 0.40 vs SR middiastole imaging and p = 0.38 vs SR end-systole imaging). The average difference of global infarct size was -0.3% and 0.2% of LV myocardium, and the limits of agreement were ± 2.4% and ± 3.3% of LV myocardium, for visual assessment and semiautomatic assessment, respectively. CONCLUSION: End-systole imaging can provide accurate diagnosis of myocardial infarction, comparable to middiastole imaging. The image quality of end-systole imaging is less susceptible to heart rate and rhythm compared with middiastole imaging.