Echocardiographic assessment of right ventricular functions in patients with proximal right coronary artery chronic total occlusion.

To assess right ventricular functions by echocardiography in patients with proximal right coronary artery (RCA) CTO and correlating it with clinical and angiographic variables. We studied 60 consecutive patients with CTO of the proximal RCA and no other significant lesions in the left coronary system. Echocardiography was performed in order to measure left ventricular (LV) dimensions, LVEF, RV end diastolic area (RVEDA), RV end systolic area (RVESA), RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), Doppler myocardial performance index (MPI), trans-tricuspid E and A waves, E/A ratio, S', e' and a'. Grades of coronary collaterals was assessed. Doppler MPI showed negative correlation with TAPSE (r = -0.8997, p < 0.0001) and RVFAC (r = -0.928, p < 0.0001). Positive correlation with trans-tricuspid E/A ratio (r = 0.893, p < 0.0001) and E/e' ratio (r = 0.783, p < 0.0001). Patients with no evidence of MI had more well-developed (grade 3) coronary collaterals (83.8 vs. 17.4 %). Patients with evidence of MI had lower RVFAC 38.13 ± 5.39 versus 45.08 ± 4.99 % (p < 0.0001), lower TAPSE 20.17 ± 3.85 versus 25.35 ± 3.46 mm (p < 0.0001), higher MPI 0.4 ± 0.08 versus 0.31 ± 0.05 (p < 0.0001), higher trans-tricuspid E/A ratio 1.79 ± 0.38 versus 1.13 ± 0.36 (p < 0.0001) and E/e' ratio 5.23 ± 1.02 versus 3.61 ± 0.88 (p < 0.0001). Patients with poorly developed collaterals had lower TAPSE and RVFAC and a higher MPI (p < 0.0001 for each). Patients with proximal RCA CTOs and evidence of inferior wall MI have significant impairment of RV functions in addition to poorly developed coronary collaterals. Those with proximal RCA CTOs and well-developed coronary collaterals have better RV functions.

Echocardiographic assessment of global longitudinal right ventricular function in patients with an acute inferior ST elevation myocardial infarction and proximal right coronary artery occlusion.

Right ventricular (RV) myocardial infarction (MI) is a frequent concomitant of an acute inferior MI. We set out to determine the diagnostic value of speckle tracking echocardiography in comparison with cardiac magnetic resonance (CMR) for RV stunning and scar prediction. 55 patients (66 ± 11 years) with an acute inferior ST elevation MI who underwent percutaneous coronary intervention (PCI) of an occlusion in the proximal right coronary artery were prospectively enrolled. An echocardiography was done on the day of presentation and on the 5th day thereafter. A CMR was subsequently performed 1 month after the MI. The CMR was used to differentiate between the group with RV scar (n = 26) and without RV scar (n = 29). RV peak systolic longitudinal strain (RV-LS) at presentation determined RV scar (-21.1 ± 5.1% vs. -9.9 ± 4.6%, p < 0.0001). The RV-LS correlated with the scar extent (r = 0.83, p < 0.0001). RV-LS > -15.8% had a sensitivity of 92% and a specificity of 83% in RV scar prediction (AUC 0.93). RV-LS was superior to TAPSE and TDI in determining the presence of RV scar. According to RV-LS values at presentation and on the 5th day, 3 subgroups were defined: G1-normal deformation (RV-LS <-20%), G2-RV stunning (baseline RV-LS >-20%, 5th day RV-LS <-20%) and G3-persistent RV dysfunction (unchanged RV-LS > -20%). In G1, there was neither RV scar nor clinically relevant hypotension. In G2, 58% of patients developed RV scar and 36% had hypotension. In the G3, 83% developed RV scar and 55% had hypotension. The myocardial deformation analysis could provide an early prediction of RV scar. It allowed the patients to be divided into subgroups with normal RV function, stunning and persistent RV dysfunction.

Impact of microvascular obstruction on the assessment of coronary flow reserve, index of microcirculatory resistance, and fractional flow reserve after ST-segment elevation myocardial infarction.

BACKGROUND: Invasive assessment of coronary physiology (IACP) offers important prognostic insights in ST-segment elevation myocardial infarction (STEMI) but the dynamics of coronary recovery are poorly understood. OBJECTIVES: This study sought to examine the evolution of coronary flow reserve (CFR), index of microcirculatory resistance (IMR), ratio of distal coronary pressure (Pd) to mean aortic pressure (Pa), and fractional flow reserve (FFR) in patients undergoing primary percutaneous coronary intervention (PPCI). METHODS: 82 patients with STEMI underwent IACP at PPCI. Repeat IACP was performed in 61 patients (74%) at day 1 and in 46 patients (56%) at 6 months. Contrast-enhanced cardiac magnetic resonance imaging (CMR) was performed in 45 patients (55%) at day 1 and in 41 patients (50%) at 6 months. Changes in IACP were compared between patients with and without microvascular obstruction (MVO) on CMR. RESULTS: MVO was present in 21 of 45 patients (47%). Patients with MVO had lower CFR at PPCI and day 1 (p < 0.05) and a trend toward higher IMR values (p = 0.07). At 6 months, CFR and IMR were not significantly different between the groups. Baseline flow and Pd/Pa remained stable over time but FFR reduced significantly between PPCI and 6 months (p = 0.008); this reduction was mainly observed in patients with MVO (p = 0.006) but not in those without MVO (p = 0.21). CONCLUSIONS: In PPCI-treated patients with STEMI, coronary microcirculation begins to recover within 24 h and recovery progresses further by 6 months. FFR significantly reduces from baseline to 6 months. The presence of MVO indicates a highly dysfunctional microcirculation.

Assessment of recanalization of chronic total occlusions on left ventricular function in patients with or without previous myocardial infarction by real-time three-dimensional echocardiography.

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2-67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1-50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1-53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.

Assessment of myocardium at risk with contrast enhanced steady-state free precession cine cardiovascular magnetic resonance compared to single-photon emission computed tomography.

BACKGROUND: Final infarct size following coronary occlusion is determined by the duration of ischemia, the size of myocardium at risk (MaR) and reperfusion injury. The reference method for determining MaR, single-photon emission computed tomography (SPECT) before reperfusion, is impractical in an acute setting. The aim of the present study was to evaluate whether MaR can be determined from the contrast enhanced myocardium using steady-state free precession (SSFP) cine cardiovascular magnetic resonance (CMR) performed one week after the acute event in ST-elevation myocardial infarction (STEMI) patients with total coronary occlusion. RESULTS: Sixteen patients with STEMI (age 64 +/- 8 years) received intravenous 99 m-Tc immediately before primary percutaneous coronary intervention. SPECT was performed within four hours. MaR was defined as the non-perfused myocardial volume derived with SPECT. CMR was performed 7.8 +/- 1.2 days after the myocardial infarction using a protocol in which the contrast agent was administered before acquisition of short-axis SSFP cines. MaR was evaluated as the contrast enhanced myocardial volume in the cines by two blinded observers. MaR determined from the enhanced region on cine CMR correlated significantly with that derived with SPECT (r2 = 0.78, p < 0.001). The difference in MaR determined by CMR and SPECT was 0.5 +/- 5.1% (mean +/- SD). The interobserver variability of contrast enhanced cine SSFP measurements was 1.6 +/- 3.7% (mean +/- SD) of the left ventricle wall volume. CONCLUSIONS: Contrast enhanced SSFP cine CMR performed one week after acute infarction accurately depicts MaR prior to reperfusion in STEMI patients with total occlusion undergoing primary PCI. This suggests that a single CMR examination might be performed for determination of MaR and infarct size.

Infarct evolution in man studied in patients with first-time coronary occlusion in comparison to different species - implications for assessment of myocardial salvage.

BACKGROUND: The time course of infarct evolution, i.e. how fast myocardial infarction (MI) develops during coronary artery occlusion, is well known for several species, whereas no direct evidence exists on the evolution of MI size normalized to myocardium at risk (MaR) in man. Despite the lack of direct evidence, current literature often refers to the "golden hour" as the time during which myocardial salvage can be accomplished by reperfusion therapy. Therefore, the aim of the present study was to investigate how duration of myocardial ischemia affects infarct evolution in man in relation to previous animal data. Consecutive patients with clinical signs of acute myocardial ischemia were screened and considered for enrollment. Particular care was taken to assure uniformity of the patients enrolled with regard to old MI, success of revascularization, collateral flow, release of biochemical markers prior to intervention etc. Sixteen patients were ultimately included in the study. Myocardium at risk was assessed acutely by acute myocardial perfusion single photon emission computed tomography (MPS) and by T2 imaging (T2-STIR) cardiovascular magnetic resonance (CMR) after one week in 10 of the 16 patients. Infarct size was measured by late gadolinium enhancement (LGE) at one week. RESULTS: The time to reach 50% MI of the MaR (T50) was significantly shorter in pigs (37 min), rats (41 min) and dogs (181 min) compared to humans (288 min). There was no significant difference in T50 when using MPS compared to T2-STIR (p = 0.53) for assessment of MaR (288 +/- 23 min vs 310 +/- 22 min, T50 +/- standard error). The transmural extent of MI increased progressively as the duration of ischemia increased (R2 = 0.56, p < 0.001). CONCLUSION: This is the first study to provide direct evidence of the time course of acute myocardial infarct evolution in relation to MaR in man with first-time MI. Infarct evolution in man is significantly slower than in pigs, rats and dogs. Furthermore, infarct evolution assessments in man are similar when using MPS acutely and T2-STIR one week later for determination of MaR, which significantly facilitates future clinical trials of cardioprotective therapies in acute coronary syndrome by the use of CMR.

Association of coronary atherosclerosis detected by multislice computed tomography and traditional risk-factor assessment.

Framingham risk score is an office-based tool used for long-term coronary heart disease risk stratification. Most acute coronary events occur in association with proximal nonobstructive atherosclerotic plaque. Multislice computed tomography detects both obstructive coronary artery disease (CAD) and proximal atherosclerotic plaque with high accuracy. The association of Framingham risk score with obstructive CAD and proximal atherosclerotic plaque was tested. Coronary multislice computed tomography was performed in 295 patients (61% men, mean age 54 +/- 13 years) without documented CAD referred for evaluation of cardiac symptoms. Framingham risk score was computed and patients were stratified according to 10-year risk (n = 213 [72%] low, n = 74 [25%] intermediate, and n = 8 [3%] high). Obstructive CAD was defined as > or =50% stenosis in > or =1 epicardial coronary artery. Proximal atherosclerotic plaque was defined as calcified or noncalcified plaque in the left main or proximal left anterior descending artery. In the low- and intermediate-Framingham risk score groups, there was a high frequency of proximal atherosclerotic plaque (44% and 75%) and obstructive CAD (16% and 34%), although both findings were more prevalent in the high-Framingham risk score group (63% for atherosclerotic plaque, 88% for obstructive CAD), respectively. Proximal atherosclerotic plaque was noncalcified in approximately 13 of patients. In women (n = 114) and younger (<55 years) patients (n = 148), most (93% and 91%, respectively) had a low Framingham risk score. There were 48 women and 51 younger patients with proximal atherosclerotic plaque, of whom only 40% (in each group) were on statin therapy. In conclusion, of patients with a low and intermediate Framingham risk score, a significant proportion had proximal atherosclerotic plaque or obstructive CAD.