RESUMEN

Comparison between coronary angiography (CA) and SPECT myocardial perfusion scintigraphy (MPS) using Tc-99m labeled compounds in 30 patients (23 males, 7 females) yielded a sensitivity of 97 percent and a specificity of 76 percent for lesion detectability (p<0.01) using CA as the reference standard. Angiographic analysis initially ascribed the scintigraphic defects in 8 patients (5 males, 3 females) as falsely positive. Eleven coronary artery territories were involved: eight within the LAD and three within the RCA. Patient symptomatology however, prompted angiographic review which revealed myocardial bridging of the LAD in one male patient and differential perfusion of the LAD in two male patients. A review of the patients' history revealed associated risk factors such as diabetes, hyperlipidaemia, hypertension and smoking. Based on these findings, critical re-evaluation of other pathophysiolocial abnormalities in the absence of vascular stenosis should thus be sought in patients with positives MPD and associated risk factors to avoid unsuspected patient morbidity (AU)

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RESUMEN

The increasing incidence of ischaemic heart disease with high mortality rate and the recent introduction of Tc99m labelled myocardial perfusion imaging agents, along with the advent of a Coronary Angiography programme in Trinidad and Tobago, prompted the comparison of the sensitivity and specificity of myocardial perfusion scintigraphy (MPS) with coronary angiography (CA). Using a standard one-day code-differential imaging protocol Single Photon Emission Computed Tomography (SPECT), images of the left ventricular myocardium of 30 patients were obtained at rest and following exercise: These images were analyzed for perfusion defects to assess each of the three main coronary arteries; the left anterior descending artery (LAD), the right coronary artery (RCA) and the left circumflex artery (LCx). The data were then correlated with the angiographic findings. MPS yielded an overall sensitivity of 97.5% and a specificity of 83.6% when compared to CA. Discordant data were obtained in the analysis of nine vascular territories with scintigraphy producing eight false positives and one false negative. The false positive cases were seen in two males and four females. Of the males, one was discovered to have intramyocardial tunnelling of the LAD artery and the other demonstrated differential perfusion between the LAD and LCx arteries. Of the females, one was classified as having Syndrome X and another demonstrated differential perfusion between the LAD and LCx arteries; the other two cases were attributed to breast attenuation. The one false negative was obtained in a patient who demonstrated good collateral circulation on angiography. MPS thus compares very well with CA in assessing the three main myocardial vascular territories.

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RESUMEN

The increasing incidence of ischaemic heart disease with high mortality rate and the recent introduction of Tc99m labelled myocardial perfusion imaging agents, along with the advent of a coronary angiography programme in Trinidad and Tobago, prompted the comparison of the sensitivity and specificity of myocardial perfusion scintigraphy (MPS) with coronary angiography (CA). Using a standard one-day code-differential imaging protocol single photon emission computed tomography (SPECT), images of the left ventricular myocardium of 30 patients were obtained at rest and following exercise: These images were analyzed for perfusion defects to assess each of the three main coronary arteries; the left anterior descenting artery (LAD), the right coronary artery (RCA) and the left circumflex artery (LCx). The data were then correlated with the angiographic findings. MPS yielded an overall sensitivity of 97.5 percent and a specificity of 83.6 percent when compared to CA. Discordant data were obtained in the analysis of nine vascular territories with scintigraphy producing eight false positive and one false negative. The false positive cases were seen in two males and four females. Of the males, one was discovered to have intramyocardial tunnelling of the LAD artery and the other demonstrated differential perfusion between the LAD and LCx arteries. Of the females, one was classified as having Syndrome X and another demonstrated differential perfusion between the LAD and LCx arteries; the other two cases were attributed to breast attenuation. The one false negative was obtained in a patient who demonstrated good collateral circulation on angiography. MPS thus compares very well with CA in assessing the three main myocardial vascular territories

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RESUMEN

The increasing incidence of ischaemic heart disease with high mortality rate and the recent introduction of Tc99m labelled myocardial perfusion imaging agents, along with the advent of a coronary angiography programme in Trinidad and Tobago, prompted the comparison of the sensitivity and specificity of myocardial perfusion scintigraphy (MPS) with coronary angiography (CA). Using a standard one-day code-differential imaging protocol single photon emission computed tomography (SPECT), images of the left ventricular myocardium of 30 patients were obtained at rest and following exercise: These images were analyzed for perfusion defects to assess each of the three main coronary arteries; the left anterior descenting artery (LAD), the right coronary artery (RCA) and the left circumflex artery (LCx). The data were then correlated with the angiographic findings. MPS yielded an overall sensitivity of 97.5 percent and a specificity of 83.6 percent when compared to CA. Discordant data were obtained in the analysis of nine vascular territories with scintigraphy producing eight false positive and one false negative. The false positive cases were seen in two males and four females. Of the males, one was discovered to have intramyocardial tunnelling of the LAD artery and the other demonstrated differential perfusion between the LAD and LCx arteries. Of the females, one was classified as having Syndrome X and another demonstrated differential perfusion between the LAD and LCx arteries; the other two cases were attributed to breast attenuation. The one false negative was obtained in a patient who demonstrated good collateral circulation on angiography. MPS thus compares very well with CA in assessing the three main myocardial vascular territories (AU)

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The assessment of myocardial perfusion has for many years been performed with thallous chloride (T1-201). This imaging agent suffers, however, from a number of well-recognized limitations, which has prompted a global search for better radiopharmaceuticals. Within the last two years, Technetium labelled myocardial perfusion imaging agents, namely, Sestamibi (Du Pont Pharma) and Tetrofosmin (Amersham) became available, and prompted us to evaluate the efficacy with respect to coronary angiography (CA) recently introduced at our institution. The data for both imaging agents were analyzed in fifty consecutive patients (ages 30 to 70 years), referred over the past eighteen months for myocardial perfusion scintigraphy (MPS). Twenty-five patients had combined MPS and CA studies. Comparative analysis for individual coronary artery territories yielded a sensitivity of 97 percent, specificity of 80 percent and an overall accuracy of 80 percent for MPS. Angiographic review of initially ascribed false positive MPS in eight patients revealed pathophysiological abnormalities other than coronary artery stenosis which accounted for the observed perfusion deficits. These included differential blood flow in two patients and myocardial bridging in one. The remaining false positives were attributed to diaphragmatic or breast attenuation (AU)

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