Noninvasive identification of left main and three-vessel coronary artery disease by thallium-201 single photon emission computed tomography during adenosine infusion

Coronary microvascular dysfunction: An important interpretation on the clinical significance of transient ischemic dilation of the left ventricle on myocardial perfusion imaging

PURPOSE

To further investigate the clinical significance of transient ischemic dilation (TID) on myocardial perfusion imaging (MPI) by analyzing the effect of anisodamine hydrobromide (a drug that can effectively ameliorate microcirculation) on the patients with isolated TID and the findings of previous literatures.

METHODS

Total 107 patients with isolated TID (TID value≥1.11) were randomly divided into group A (n = 36; intravenous administration of anisodamine hydrobromide), group N (n = 36; intravenous administration of isosorbide dinitrate), and group C (n = 35; intravenous administration of normal saline). MPI and treadmill exercise test (TET) were performed again after 14-day course of intervention. Pre- and post-intervention frequencies of symptom were recorded.

RESULTS

In group A, after intervention of anisodamine hydrobromide, the summed stress score (SSS) and TID value on MPI significantly decreased than those before intervention (P < 0.001), the durations of exercise (DEs) and metabolic equivalents (METs) in TET notably ascended (P < 0.001), as well as the symptom remarkably improved. In group N and group C, there were no significant differences in SSS, TID value, DEs, METs, and frequencies of symptom between pre- and post-intervention (P > 0.05). No significant improvement of symptoms in group N before and after treatment.

CONCLUSIONS

TID with perfusion defect may usually predict a possibility of severe and extensive coronary artery disease (CAD). An isolated TID should be considered as a likelihood of coronary microvascular dysfunction (CMD). TET and coronary CT angiography (cCTA) are extremely helpful for the antidiastole on CAD and CMD. The administration of anisodamine hydrobromide might be an optional treatment for the patients with isolated TID.

Myocardial perfusion imaging in patients with unprotected left main disease

BACKGROUND

The management of patients with unprotected left main (LM) coronary artery disease remains challenging, with recent data casting a shadow of doubt on the safety of percutaneous coronary intervention. We aimed at describing the features of patients undergoing myocardial perfusion imaging (MPI) subsequently found to have LM disease.

METHODS

We queried our institutional database for subjects without prior revascularization or myocardial infarction (MI), who had undergone MPI followed by invasive coronary angiography within 6 months, comparing those with evidence of angiographically significant LM disease (i.e. diameter stenosis ≥50%) to those without significant coronary artery disease (CAD), or those with CAD not involving LM. Baseline, stress and imaging features were systematically collected and analyzed, and clinical outcomes (death, myocardial infarction, revascularization) sought.

RESULTS

We included a total of 74 patients with LM disease, which were compared with 70 without CAD, and 920 with significant CAD not involving LM. MPI was remarkably safe in all subjects, and significant differences were found for several features, but particularly so for ST change, rate pressure product, and left ventricular ejection fraction (all P<0.05). Most patients with LM disease had moderate or severe ischemia, and the apical, lateral and inferior regions were the most sensitive ones. Clinical outcomes after an average of 35 months were worse in patients with LM disease than in subjects with significant CAD not involving LM, albeit non-significantly, possibly in light of the higher use of coronary artery bypass grafting.

CONCLUSIONS

MPI is safe and informative in patients with LM disease, and multidimensional appraisal of MPI results may guide decision-making on top of providing prognostic detail and warranty period.

Use of Extracorporeal Membrane Oxygenation to Rescue Patients With Refractory Ventricular Arrhythmia in Acute Myocardial Infarction

Refractory ventricular arrhythmia is a serious problem in acute myocardial infarction (AMI), with an extremely high mortality rate and limited effective treatment. Extracorporeal membrane oxygenation (ECMO) is useful to rescue patients with cardiopulmonary collapse. However, little is known about whether ECMO is a potential rescue technique for patients with refractory ventricular arrhythmia in AMI.We retrospectively analyzed prospectively collected data on patients with AMI and refractory ventricular arrhythmia who underwent ECMO as rescue therapy and the bridge to revascularization from February 2001 to January 2013. Primary endpoint was mortality on index admission, and secondary endpoint was mortality on index admission or advanced brain damage at discharge.A total of 69 (62 men) patients were enrolled in this study. During the index admission, 39 patients (56.5%) met primary endpoint, and 45 patients (65.2%) met secondary endpoint, respectively. In multivariate Cox regression analysis, both the presence of profound anoxic encephalopathy and acute renal failure requiring dialysis were significant predictive factors for both primary and secondary endpoints.ECMO is a feasible rescue therapy and bridge to revascularization in patients with refractory ventricular arrhythmia in acute myocardial infarction. The presence of profound anoxic encephalopathy and acute renal failure requiring dialysis were significant prognostic factors.

Role of nuclear cardiology in advancing cardiac surgery

Cardiac surgeons are commonly faced with issues regarding the balance between the potential risk and the potential benefit of a surgical procedure. Nuclear cardiology procedures [myocardial perfusion SPECT (MPS) and positron emission tomography (PET)] provide the surgeon with objective information that augments standard clinical and angiographic assessments with respect to diagnosis, prognosis, and potential benefit from intervention. Development of the technology and methodology of gated MPS acquisition and interpretation allows assessment of the extent and severity of hypoperfused but viable myocardium, as well as global LVEF and LV volume measurements, diastolic function, and LV geometry. With PET, myocardial metabolism and blood flow reserve can also be measured. This chapter provides insight into the current evidence regarding settings in which nuclear cardiology procedures are helpful to the surgeon in assessment of patients having or being considered for cardiac surgery in the setting of coronary artery disease (CAD). Overall, a risk-benefit approach to MPS results is proposed, with principal focus on identifying patients at risk for major cardiac events who may benefit from a surgical procedure.

Transient ischemic dilation ratio of the left ventricle is a significant predictor of future cardiac events in patients with otherwise normal myocardial perfusion SPECT

OBJECTIVES

This study evaluated the prognostic value of transient ischemic dilation (TID) of the left ventricle (LV) in patients with normal stress myocardial perfusion single photon emission computed tomography (MPS).

BACKGROUND

The prognostic value of TID in patients with an otherwise normal MPS has not been defined.

METHODS

We identified 1,560 patients who had normal stress MPS (436 vasodilator and 1,124 exercise stress), and no rest LV enlargement (Population 1) and followed up for 2.30 +/- 0.67 years for hard events (HE) (cardiac death or myocardial infarction) and soft events (SE) (revascularization). Prediction of first HE or SE (total events [TE]) was evaluated by multivariable Cox analysis, which was also applied to a broader group of 2,037 patients (including patients with minimal defects (Population 2).

RESULTS

In Population 1, there were 13 HE, 36 SE, and 42 TE. Patients in the highest TID quartile (TID > or =1.21) had a higher TE rate than others, regardless of stress type. By multivariable analysis, highest TID quartile was predictive of TE (p = 0.008). Other independent predictors of TE were age, typical angina, and diabetes. In Population 2, TID was also predictive of TE.

CONCLUSIONS

An entirely normal stress MPS study does not always imply an excellent prognosis. In patients with otherwise normal MPS, TID is an independent and incremental prognostic marker of TE even after significant clinical variables--age, typical angina, and diabetes--are accounted for. When TID is present, caution in making low-risk prognostic statements may be warranted, especially in patients with typical angina, the elderly, and diabetics. Our findings also appear to apply to the broader population of "normal" MPS, which included patients with minimal perfusion defects.

Predictive potential of noninvasive methods, inclusive of exercise SPECT Tc99m MIBI imaging, in recognition of high-risk patients with left main coronary artery stenosis

The aim of the present study was to determine which clinical, exercise and perfusion variables can be instrumental in the identification of left main coronary artery. A multivariate model for prediction of left main disease was developed, based on a number of clinical, exercise and MIBI perfusion variables in two groups of patients. Group I consisted of 38 patients (30 men and eight women) with angiographically proven left main stenosis, while group II consisted of 41 patients (27 men and 14 women) with multivessel coronary artery diseases. A multivariate logistic regression analysis demonstrated that clinical variables including diabetes, hypertension, together with history of typical angina were the only independent predictors of left main stenosis. It was found that p value was 0.05 for hypertension, 0.01 for diabetes as well as 0.01 for the history of typical angina in clinical examination. No exercise or perfusion variables may be instrumental in prediction of left main stenosis, when considered in isolation. Myocardial perfusion by itself is therefore not deemed sufficiently specific to attempt its positive identification. High-risk patients with left main disease can be identified noninvasively by exercise perfusion imaging using a model based on the proposed logistic regression analysis with clinical variables.

Improved detection of left main coronary artery disease with attenuation-corrected SPECT

BACKGROUND

Myocardial perfusion imaging has demonstrated a limited sensitivity as a means of accurately identifying left main (LM) coronary disease. Because regional quantitative perfusion biases are eliminated with attenuation corrected (AC) single photon emission computed tomography (SPECT), as compared with uncorrected (NC) SPECT, we hypothesized that AC SPECT would demonstrate increased diagnostic accuracy for the detection of significant LM coronary stenosis.

METHODS AND RESULTS

We studied 28 patients (23 men, 5 women; mean age, 66+/-9 years) with significant LM stenoses (> or =50%) and 34 control patients (27 men, 7 women; mean age, 65+/-11 years) with 2-vessel coronary disease. Rest thallium-201 and stress technetium 99m sestamibi SPECT imaging with and without AC were performed, as described earlier. Both AC and NC images were analyzed visually and quantitatively in comparison with corresponding normal databases. A greater sensitivity for detection of an LM defect pattern (64% vs. 7%, P = .0009) with equivalent specificity (94% vs. 100%, P = not significant) was demonstrated by means of visual analysis of AC SPECT images. More disease was demonstrated in a greater number of territories with AC SPECT images than with NC images (2.14+/-0.97 for AC images vs. 1.43+/-0.84 for NC images, P = .0001). Similar improvement in the detection of LM disease was shown by means of automated quantitative analysis (57% for AC SPECT vs 14% for NC SPECT, P = .0005), again with no loss in specificity.

CONCLUSIONS

AC SPECT with the University of Michigan method in consecutive patients with LM stenoses and a select control population with severity matched multivessel coronary disease significantly improved the diagnostic accuracy of myocardial perfusion imaging for the identification of LM coronary disease, compared with uncorrected SPECT.