Dipyridamole administration at the end of an insufficient exercise Tc-99m MIBI SPECT improves detection of multivessel coronary artery disease in patients with previous myocardial infarction

Plasma B-type natriuretic peptide levels are poorly related to the occurrence of ischemia or ventricular arrhythmias during symptom-limited exercise in low-risk patients

INTRODUCTION

The usefulness of B-type natriuretic peptide (BNP) as a marker of ischemia is controversial. BNP levels have predicted arrhythmias in various settings, but it is unknown whether they are related to exercise-induced ischemic ventricular arrhythmias.

MATERIAL AND METHODS

We analyzed in 63 patients (64 ±14 years, 65% male, 62% with known coronary disease) undergoing exercise stress single-photon emission computed tomography (SPECT) the association between plasma BNP values (before and 15 min after exercise) and the occurrence of ischemia or ventricular arrhythmias during the test.

RESULTS

Exercise test (8.1 ±2.7 min, 7.4 ±8.1 metabolic equivalents, 82 ±12% of maximal predicted heart rate) induced reversible perfusion defects in 23 (36%) patients. Eight (13%) patients presented significant arrhythmias (≥ 7 ventricular premature complexes/min, couplets, or non-sustained ventricular tachycardia during exercise or in the first minute of recovery). Median baseline BNP levels were 17.5 (12.4-66.4) pg/ml in patients developing scintigraphic ischemia and 45.6 (13.2-107.4) pg/ml in those without ischemia (p = 0.137). The BNP levels increased after exercise (34.4 (15.3-65.4)% increment over baseline, p < 0.001), but the magnitude of this increase was not related to SPECT positivity (35.7 (18.8-65.4)% vs. 27.9 (5.6-64.0)% in patients with and without ischemia, respectively, p = 0.304). No significant association was found between BNP values (at baseline or their change during the test) and ventricular arrhythmias.

CONCLUSIONS

Plasma BNP values - at baseline or after exercise - were not associated with myocardial ischemia or with ventricular arrhythmia during exercise SPECT. These results highlight the limited usefulness of this biomarker to assess acute ischemia.

Usefulness of exercise test and myocardial perfusion-gated single photon emission computed tomography to improve the prediction of major events

BACKGROUND

The incremental prognostic value of myocardial perfusion-gated single photon emission computed tomography (MPGS) compared with exercise test has not yet been properly evaluated.

METHODS AND RESULTS

Five thousand six hundred seventy-two consecutive patients with known or suspected coronary disease undergoing exercise MPGS between 1997 and 2007 were included. Three-year predictive models for total death and death from cardiovascular causes or acute myocardial infarction (ie, major cardiovascular events [MCE]) were built using Cox-regression modeling, including only the clinical information. Then the exercise and MPGS information was sequentially added. The added discriminative ability of exercise test information and MPGS was assessed by net reclassification improvement and integrated discrimination improvement. The increase in predictive ability of exercise information for death and MCE was high as assessed by net reclassification improvement (0.199 and 0.263) and integrated discrimination improvement (0.042 and 0.021). The only variable of MPGS associated with total death was ejection fraction (hazard ratio, 0.84; 95% confidence interval, 0.79-0.89; P<0.001). Global stress ischemic score emerged as an additional variable associated with MCE (hazard ratio, 1.07; 95% confidence interval, 1.02-1.12; P=0.007). Adding MPGS information barely improved the prognostic value for total death (net reclassification improvement, 0.017; integrated discrimination improvement, 0.013), but it increased for MCE (net reclassification improvement, 0.122; integrated discrimination improvement, 0.033).

CONCLUSIONS

Adding MPGS information to exercise information does not improve prediction of total death, although it allows a more accurate prediction of MCE.

Prognostic value of myocardial perfusion-gated SPECT in patients with ischemic cardiomyopathy

BACKGROUND

There are no extensive series in which risk stratification of patients with ischemic cardiomyopathy (IC) is based on their rest and exercise and scintigraphic characteristics. The purpose of our study was to analyze rest and exercise myocardial perfusion-gated SPECT variables for prognosis in patients with ischemic IC.

METHODS AND RESULTS

Prospective cohort study. A study was performed in 167 patients with IC who consecutively underwent rest myocardial perfusion-gated SPECT. In addition, stress SPECT was performed on 137 of these patients. During an average follow-up of 2.3 +/- 1.2 years, cardiac mortality (CM) was 17.4%. Independent predictors of CM in rest-gated SPECT were the positive criteria for myocardial viability (P = 0.027; Hazard risk, HR: 5.1; 95% CI: 1.2-21.4). In the 137 patients who underwent stress-gated SPECT, predictors were scintigraphic criteria for viability plus ischemia (P = 0.026; HR: 3.6; 95% CI: 1.16-11.2) and exercise duration < or = 5 minutes (P = 0.04; HR: 2.7; 95% CI: 1.01-7.36). Coronary angiography variables, performed in 111 patients, did not significantly modify the prognostic value of non-invasive testing.

CONCLUSION

Myocardial perfusion-gated SPECT improves prognostic stratification of patients with IC.

Sensitivity, Specificity, Positive Predictive Value, and Negative Predictive Value of the Dipyridamole Sestamibi Stress Test Comparing Arterial to Vein Conduits

STUDY OBJECTIVES

To determine the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the dipyridamole stress test (DSST) in predicting > or = 50% obstruction of an internal mammary artery or new native coronary artery disease (CAD) compared with saphenous vein graft obstruction > or = 50% in patients with prior coronary artery surgery and symptoms.

DESIGN

In 144 patients with prior coronary artery surgery who underwent a DSST within 8 +/- 7 days of coronary angiography performed because of cardiac symptoms, we investigated the sensitivity, specificity, PPV, and NPV of the DSST in predicting > or = 50% obstruction of an internal mammary artery or new native CAD (201 total arterial conduits) vs > or = 50% obstruction of saphenous vein grafts (total saphenous grafts = 246).

SETTING

A university hospital.

PATIENTS

The 144 patients included 88 men and 56 women, mean age 68 +/- 9 years (+/- SD).

RESULTS

The DSST had a sensitivity of 81%, a specificity of 87%, a PPV of 84%, and a NPV of 84% in predicting > or = 50% obstruction of an internal mammary artery or new native CAD. The DSST had a sensitivity of 88%, a specificity of 82%, a PPV of 86%, and a NPV of 85% in predicting > or = 50% obstruction of saphenous vein grafts.

CONCLUSION

There was no significant difference in sensitivity, specificity, PPV, or NPV of the DSST in predicting > or = 50% obstruction of an internal mammary artery or new native CAD vs predicting > or = 50% obstruction of saphenous vein grafts in patients with prior coronary artery surgery and cardiac symptoms.

Sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test in predicting graft occlusion or > or = 50% new native coronary artery disease in men versus women and in patients aged > or = 65 years versus < 65 years who had prior coronary artery bypass grafting

The sensitivity, specificity, positive predictive value, and negative predictive value of the dipyridamole sestamibi stress test (DSST) in predicting graft obstruction or > or = 50% new native coronary artery disease (CAD) in 88 men compared with 56 women with prior coronary artery bypass surgery were 96% and 94% (p = NS), 30% and 67% (p = NS), 91% and 96 % (p = NS), 50% and 57% (p = NS), respectively. The sensitivity, specificity, positive predictive value, and negative predictive value of the DSST in predicting graft obstruction or > or = 50% new native CAD in 92 patients aged < 65 years were 95% and 95% (p = NS), 50% and 40% (p = NS), 96% and 87% (p = NS), and 43% and 67% (p = NS), respectively.

Usefulness of myocardial perfusion SPECT in patients with left bundle branch block and previous myocardial infarction

BACKGROUND

The diagnostic value of myocardial perfusion scintigraphy in patients with left bundle branch block (LBBB) and previous acute myocardial infarction has not been evaluated.

OBJECTIVE

To determine the utility of single photon emission computed tomography (SPECT) in patients with LBBB and previous acute myocardial infarction.

METHODS

Seventy two consecutive patients with permanent LBBB and previous acute myocardial infarction were studied with stress-rest SPECT using 99mTc compounds. The same stress procedures were followed in all patients: (1) exercise alone when it was sufficient; (2) exercise plus simultaneous administration of dipyridamole if exercise was insufficient.

RESULTS

In 26 of 28 patients (93%) who had a Q wave acute myocardial infarct before the development of LBBB, there was concordance between abnormal Q waves and rest SPECT in the localisation of myocardial necrosis (kappa = 0.836; p = 0.0001). In 48 patients who had coronary angiography, the positive predictive value of exercise (+dipyridamole) myocardial SPECT for the diagnosis of left anterior descending coronary artery stenosis was 93%, for left circumflex coronary artery stenosis, 96%, and for right coronary artery stenosis, 89%. Specificity values were 83%, 91%, and 69%, respectively. However, sensitivity (69%, 64%, and 89%) and negative predictive values (48%, 46%, and 82%) were suboptimal.

CONCLUSIONS

Rest myocardial perfusion SPECT with technetium compounds is useful for localising healed myocardial infarction in patients with LBBB, and exercise (+dipyridamole) SPECT has a high positive predictive value and specificity for the diagnosis of coronary stenosis in these patients.