Effect of cardiac resynchronization therapy on septal perfusion and septal thickening: Association with left ventricular function, reverse remodelling and dyssynchrony.

BACKGROUND: We evaluated the effect of cardiac resynchronization therapy (CRT) on septal perfusion and thickening at 6 months post implantation assessed on Tc99m-MIBI Gated myocardial perfusion SPECT (GMPS).We also studied the association of change in septal perfusion and thickening with primary outcome defined as at least one [improvement in ≥1NYHA class, left ventricular ejection fraction (LVEF) by ≥ 5%, reduction of end-systolic volume (ESV) by ≥ 15%, and improvement ≥ 5 points in Minnesota living with heart failure questionnaire (MLHFQ)]. METHOD: One hundred and five patients underwent clinical and GMPS evaluation before and at 6 months post CRT. RESULT: Post CRT there was significant improvement in mean normalized septal perfusion uptake and in septal thickening (P value = 0.001, both). There was no significant relation between improvement in septal perfusion and primary outcome. However, improvement in septal thickening was statistically significant with favorable primary outcome (P = 0.001).There was no significant correlation between improvement of septal perfusion and improvement in LVEF, reduction in End diastolic volume (EDV), ESV, and Left ventricular Dyssynchrony (LVD). But, there was significant correlation between improvement of septal thickening and these parameters. CONCLUSION: Improvement in septal thickening was associated with reverse remodeling, improvement in LVEF, and reduction of LVD.

Myocardial ischaemia in patients with primary APS: a 13N-ammonia PET assessment.

OBJECTIVE: Evaluate the presence and severity of myocardial ischaemia in a population of asymptomatic patients with primary APS (PAPS) using (13)N-ammonia PET. METHODS: We studied 36 patients, 18 with a diagnosis of PAPS and 18 healthy volunteers. All patients underwent a two-phase (rest-stress) (13)N-ammonia PET. Myocardial perfusion images were acquired and then analysed by two experts in the field. RESULTS: We found ischaemia in 7/18 asymptomatic PAPS patients (38.8%). The anterolateral wall was the most commonly affected cardiac territory [5/7 PAPS patients (71.4%)]. In a severity analysis, we found that five patients (71.4%) had mild ischaemia, one patient (14.2%) had moderate ischaemia and another one (14.2%) had severe defects. All the healthy volunteers studied showed normal myocardial perfusion images. CONCLUSION: An important proportion of PAPS patients, even when asymptomatic, showed myocardial perfusion defects assessed with PET. Most of the ischaemic patients had mild defects and the anterolateral wall was the territory mainly affected.

Cardiopatía isquémica: evaluación anatomofuncional en una sola exploración con PET-CT multicorte / Ischemic heart disease: anatomic and functional evaluation in a single exploration with multi-slice PET-CT

A complete evaluation of the patient with ischemic heart disease requires an anatomical and functional assessment of the myocardium and coronary arteries. Recent technological advances have allowed a quantitative and physiological evaluation of the cardiovascular system with Positron Emission Tomography (PET). This method is a valuable tool for the assessment of heart metabolism, myocardial perfusion, ventricular function, coronary blood flow, myocardial viability and endothelial function. One of the major limitations of a PET study is its low spatial resolution. Cardiac Computed Tomography (CCT) is an anatomic study used for coronary calcium quantification, evaluation of wall and lumen of coronary arteries, study of vascular permeability and assessment of composition, extension and severity of atherosclerotic plaques. The main limitation of CCT is the lack of functional information that is obtained with this technique. Both methods are complementary in many ways. That is the reason of the wide spread of PET-CT hybrid equipments that can provide very useful functional and anatomic information of patients with ischemic heart disease in a single exploration.

El patrón discordante, representación visual de viabilidad miocárdica con PET / Discordant pattern, visual identification of myocardial viability with PET

PET (positron emission tomography) as a non-invasive imaging method for studying cardiac perfusion and metabolism has turned into the gold standard for detecting myocardial viability. The utilization of 18 FDG as a tracer for its identification permits to spot the use of exogenous glucose by the myocardium segments. By studying and comparing viability and perfusion results, for which the latter uses tracers such as 13N-ammonia, three different patterns for myocardial viability evaluation arise:. transmural concordant pattern, non-transmural concordant pattern, and the discordant pattern; the last one exemplifies the hibernating myocardium and proves the presence of myocardial viability. The importance of its detection is fundamental for the study of an ischemic patient, since it permits the establishment of and exact diagnosis, prognosis, and the best treatment option. It also allows foreseeing functional recovery of the affected region as well as the ejection fraction rate after revascularization treatment if this is determined as necessary. All these elements regarding viability are determinant in order to reduce adverse events and help improving patients' prognosis.

[Discordant pattern, visual identification of myocardial viability with PET]. / El patrón discordante, representación visual de viabilidad miocárdica con PET.

PET (positron emission tomography) as a non-invasive imaging method for studying cardiac perfusion and metabolism has turned into the gold standard for detecting myocardial viability. The utilization of 18 FDG as a tracer for its identification permits to spot the use of exogenous glucose by the myocardium segments. By studying and comparing viability and perfusion results, for which the latter uses tracers such as 13N-ammonia, three different patterns for myocardial viability evaluation arise:. transmural concordant pattern, non-transmural concordant pattern, and the discordant pattern; the last one exemplifies the hibernating myocardium and proves the presence of myocardial viability. The importance of its detection is fundamental for the study of an ischemic patient, since it permits the establishment of and exact diagnosis, prognosis, and the best treatment option. It also allows foreseeing functional recovery of the affected region as well as the ejection fraction rate after revascularization treatment if this is determined as necessary. All these elements regarding viability are determinant in order to reduce adverse events and help improving patients' prognosis.

[Evaluation of coronary flow by means of PET in the Mexican population without coronary artery disease]. / Valoración del flujo coronario mediante PET en lapoblación mexicana sin enfermedad arterial coronaria.

UNLABELLED: Coronary artery disease (CAD) represents the principal cause of morbidity and mortality in our environment. Positron emission tomography (PET) is a new technique in our country that allows the assessment of myocardial perfusion and the absolute quantification of the coronary blood flow (CBF) through the utilization of radiotracers using the same criteria employed in conventional nuclear cardiology. CBF normal values have been determined in other populations around the world. No studies in our country assessing in a non-invasive way the CBF have been published before. The quantification of CBF in healthy population is important to establish a standard measure and determine through it, the effects of the many diseases that change the coronary blood flow. The quantification of the CBF, the calculation of coronary blood flow reserve (CFR) and the endothelium dependent vasodilatation index (EDVI) through PET is possible performing three different acquisition stages: rest, cold pressor test (CPT) and pharmacologic stress using Ammonia as radiotracer. The aim of this study was to evaluate the CBF, the CFR and the EDVI in healthy Mexican volunteers. RESULTS: Global basal CBF was 0.34 (+/- 0.09) mL/g/min, during CPT increased to 0.55 (+/- 0.17) mL/g/min and during the stress increased to 1.18 (+/- 0.25). CFR was 3.5 (+/- 0.65) and EDVI was 1.55 (+/- 0.33). CONCLUSIONS: CFR and EDVI values obtained in Mexican healthy population correlates very well with those reported in the literature. This values represents a reference to further research that use this technology.

Valoración del flujo coronario mediante PET en la población mexicana sin enfermedad arterial coronaria / Evaluation of coronary flow by means of PET in the Mexican population without coronary artery disease

La enfermedad arterial coronaria (EAC) representa la primera causa de morbi mortalidad en nuestro medio. La tomografía por emisión de positrones (PET) es una técnica novedosa en nuestro país mediante la cual es posible valorar la perfusión miocárdica a través de radiotrazadores, lo que permite detectar defectos de perfusión utilizando los mismos criterios que en cardiología nuclear. A su vez, a través del estudio del flujo coronario (FC) es posible detectar la EAC en sus etapas más tempranas. El FC ha sido determinado en otras poblaciones a nivel mundial, sin embargo, hasta el momento no existen estudios en nuestro país que lo hayan valorado de manera no invasiva. La importancia de determinar el FC en voluntarios sanos radica en establecer una base para poder comparar estos resultados con los encontrados en pacientes con diferente patología que afecte el flujo coronario. Para la determinación del FC y la reserva de flujo coronario (RFC) y del índice de vasodilatación dependiente de endotelio (IVED) mediante PET se realizan 3 mediciones en 3 fases distintas: reposo, estimulación con frío (CPT) y esfuerzo farmacológico, con la utilización de amonio. Objetivo: Determinar el FC en las tres fases en población sana con la utilización de amonio-PET. Resultados: El FC global basal fue de 0.34 (±0.09) mL/g/min, durante el CPT incrementó a 0.55 (±0.17) mL/g/min y con el estrés llegó a 1.18 (±0.25). La RFC fue de 3.5 (±0.65) y el IVED de 1.55 (±0.33). Conclusiones: Los valores obtenidos de RFC y de IVED en población mexicana sana coincide con los reportados en la literatura. Estos valores representan una base de referencia para las investigaciones futuras con esta tecnología en nuestro país.

Coronary artery disease (CAD) represents the principal cause of morbidity and mortality in our environment. Positron emission tomography (PET) is a new technique in our country that allows the assessment of myocardial perfusion and the absolute quantification of the coronary blood flow (CBF) through the utilization of radiotracers using the same criteria employed in conventional nuclear cardiology. CBF normal values have been determined in other populations around the world. No studies in our country assessing in a non-invasive way the CBF have been published before. The quantification of CBF in healthy population is important to establish a standard measure and determine through it, the effects of the many diseases that change the coronary blood flow. The quantification of the CBF, the calculation of coronary blood flow reserve (CFR) and the endothelium dependent vasodilatation index (EDVI) through PET is possible performing three different acquisition stages: rest, cold pressor test (CPT) and pharmacologic stress using Ammonia as radiotracer. The aim of this study was to evaluate the CBF, the CFR and the EDVI in healthy Mexican volunteers. Results: Global basal CBF was 0.34 (±0.09) mL/g/min, during CPT increased to 0.55 (±0.17) mL/g/min and during the stress increased to 1.18 (±0.25). CFR was 3.5 (±0.65) and EDVI was 1.55 (±0.33). Conclusions: CFR and EDVI values obtained in Mexican healthy population correlates very well with those reported in the literature. This values represents a reference to further research that use this technology.

[Diastolic dysfunction and heart failure]. / Disfunción diastólica e insuficiencia cardiaca.

Systolic and diastolic dysfunctions might present same symptomatology, but these are totally different entities. Diastolic dysfunction is a common disease. The most important causes are coronary artery disease and/or left ventricular hypertrophy. This disease has to be diagnosed and treated according to the physiopathology mechanism. Several mechanisms exist that influence and determine diastolic function, if one or a combination of them is altered; this would result in a wide clinical spectrum ranging from a patient without symptoms to an incapacitating state.

[Myocardial perfusion evaluated with a 2-isotope technique. Experience with the first 1600 cases in Mexico]. / Perfusión miocárdica valorada con técnica de dos isótopos. Experiencia de los primeros 1600 casos en México.

SPECT has a high sensitivity for the diagnosis of coronary artery disease. Dual isotope protocol using rest thallium and stress MIBI was introduced in Mexico 4 years ago. This protocol reunite the advantages of both radiotracers for the study of myocardial perfusion. We present our experience of the first three years. One thousand six hundred patients were studied with suspected myocardial ischemia; 288 were excluded because of an absence of a proper follow up. In 895 of the 1312 patients a coronariography was performed. Images were evaluated by dividing the heart in 20 segments using a 5 points scale (0 = normal to 4 = absence of perfusion). It was considered a perfusion defect when a segment had a score greater or equal to 2 and the SPECT study was considered abnormal if two or more segments had a MIBI stress score equal or greater than 2. The global sensitivity for diagnosis of ischemia was 96.28%. Dual isotope method is appropriate for the diagnosis of ischemic heart disease. It has a high sensitivity and specificity for the recognition of global coronary disease and for specific coronary territories. This work constitutes the greatest series in Latin America that uses this diagnosis method.

[Simultaneous analysis of myocardial perfusion and ventricular function. Normal values in the Mexican population]. / Análisis simultáneo de la perfusión miocárdica y la función ventricular. Valores de normalidad en la población Mexicana.

UNLABELLED: Myocardial perfusion imaging is an useful procedure in the evaluation of patients with coronary artery disease, Gated SPECT technique evaluates simultaneously perfusion and ventricular function, left ventricular ejection fraction (LVEF), ventricular volumes and the transient ischemic dilatation of the left ventricle. OBJECTIVE: To evaluate the normal ventricle volumes and the ejection fraction of the LV obtained automatically with the Gated SPECT in Mexican population. METHODS: 100 patients were studied with low likelihood for CAD. All of them were studied with Tc-99m Sestamibi Gated SPECT. We obtained automatically the LVEF, and the end diastolic and systolic left ventricular volumes. RESULTS: Myocardial perfusion, regional motion and systolic thickening were normal in all patients. We obtained the mean values of EF and end diastolic and systolic volumes. These values were lower in female. CONCLUSION: Tc-99m Sestamibi myocardial perfusion SPECT is an useful procedure, with high accuracy for the simultaneous evaluation of myocardial perfusion and ventricular function.

[Simultaneous assessment of myocardial perfusion and ventricular function using thallium-201 at rest/Tc-99m tetrofosmin at effort with single-photon emission computerized tomography, synchronized with electrocardiogram (synchronized SPECT). Initial experience in Latin America]. / Evaluación simultánea de la perfusión miocárdica y función ventricular utilizando talio-201 en reposo/Tc-99m Tetrofosmin en esfuerzo mediante tomografía computada por emisión de fotón único, sincronizada con el electrocardiograma (Spect sincronizado). Experiencia inicial en Latinoamérica.

UNLABELLED: Gated SPECT is a useful technique to evaluate myocardial perfusion, wall motion abnormalities and wall thickening. There is not published experience in Latin-America using dual isotope rest Thallium-201/stress Tc-99m Tetrofosmin Gated SPECT. METHOD: We studied 27 patients with coronary artery disease. Coronary angiography was performed in all the patients. We used an injection at rest of 3 mCi of Thallium-201 followed by stress and the administration of 15 mCi of Tetrofosmin and Gated SPECT acquisition. Five days after, the patients were injected with 20 mCi of Sestamibi at stress, with a second Gated SPECT acquisition. Perfusion data were analyzed using 20 SPECT segment analysis. To study the wall motion, we divided the heart in 29 segments and every segment was scored using a 4 points scale (3 = normal, 2 = mild hipokinesia, 1 = severe hipokinesia, 0 = akinesia). RESULTS: The perfusion and wall motion segmental score agreement between stress Tc-99m tetrofosmin and stress Tc-99m sestamibi were 97% and 84% respectively. CONCLUSIONS: Rest Thailium-201/stress Tc-99m Tetrofosmin Dual isotope Gated SPECT technique is a good protocol to assess simultaneous myocardial perfusion and wall motion. There is a good agreement of the results with the use of rest Thallium-201/stress Tc-99m Sestamibi Dual isotope Gated SPECT study.

[Myocardial ischemia detection with adenosine administration and SPECT. Initial experience in Mexico]. / Detección de isquemia miocárdica mediante la administración de adenosina y técnica SPECT. Experiencia inicial en México.

UNLABELLED: Myocardial perfusion SPECT has a high sensitivity for the diagnosis of myocardial ischemia. Adenosine has been recently used to induce myocardial ischemia in the United States and Europe. At the present time there is not published experience using adenosine in Mexico. METHOD: We studied 22 patients with suspected myocardial ischemia. Coronary angiography was performed in 17 patients. We used a 8 mCi rest Tc-99m sestamibi followed by a 6 minute infusion of adenosine at a dose of 140 ug/kg/min; 24 mCi of Tc-99m were injected after the third minute of adenosine infusion. Patients returned 2 or 3 days later for a new stress study using physical stress or dipiridamole and the images were read using a 20 segments analysis and each segment was scored using a 5 points scale (0 = normal to 4 = absent uptake). The results were then compared with the adenosine images. RESULTS: The segmental score agreement between adenosine and physical or dipyridamole stress were good with 90% exact correlation. The side effects experienced by patients who received dipyridamole and adenosine were similar. CONCLUSION: Adenosine is a good alternative to induce myocardial ischemia. It showed a good correlation with physical or dipyridamole stress test.

[Simultaneous assessment of perfusion and myocardial viability with 2 isotope studies (thallium at rest and sestamibi in exercise). Initial experience in Mexico and Latin America]. / Valoración simultánea de la perfusión y la viabilidad miocárdica a través del estudio de dos isótopos (Talio reposo/MIBI esfuerzo). Experiencia inicial en México y América Latina.

UNLABELLED: Rest-stress sestamibi single photon emission computed tomography (SPECT) has sensitivity and specificity similar to those of thallium 201 SPECT for detection of coronary artery disease. However, sestamibi is not ideal agent to study myocardial viability. There is not published experience in Latin American using dual isotope SPECT protocol to evaluate myocardial perfusion and viability. We studied 44 consecutive patients with coronary artery disease, 37 of them with previous myocardial infarction. Coronary angiography was performed in all patients. We used a 3 mCi rest T 201 SPECT followed by stress and 25 mCi sestamibi injection. Sestamibi SPECT was performed 30 minutes after exercise or 1 hour after pharmacologic stress with dipyridamole. To validate perfusion findings patients returning next day for rest sestamibi injection and SPECT. Scintigraphic data were read by two blinded expert using 20 SPECT segment analysis and each segment was scored using 5 points scoring system (0 = normal, 4 = absent uptake). The segmental score agreement between rest thallium 201 and rest sestamibi and the comparison of defect reversibility percentage and non reversibility between both protocols was 90.7%. CONCLUSION: Separate acquisition dual isotope myocardial perfusion SPECT is accurate for coronary artery disease evaluation. It showed a good agreement with rest-stress sestamibi SPECT for assessment of rest perfusion defects and reversibility and it was a better method to evaluate myocardial viability.

[Usefulness of SPECT (single-photon emission-computed tomography) in the detection of coronary disease]. / Utilidad del SPECT (tomografía computada por emisión de fotón único) en la detección de enfermedad aterosclerosa coronaria.

OBJECTIVE: To evaluate the clinical usefulness of cardiac SPECT in the detection of coronary artery disease, and the relation with the site, number and severity of the angiographic lesions. METHOD: We studied 216 patients; with myocardial perfusion imaging with SPECT (T1-201 and/or Tc-99 Sestamibi) and coronary angiogram. We defined the localization of myocardial perfusion defects (anterior, inferior, septal, lateral or apex), and their correlation with coronary angiogram, based on the location, number and severity of coronary angiographic lesions. We considered significative coronary stenosis obstructions of 60% or more. RESULTS: Of the 216 patients studied, 181 (83.8%) were male and 35 (16.2%) female. Age ranged between 30 and 82 years; 143 males and 23 females had a previous myocardial infarction. The SPECT sensitivity for diagnosing ischemia of one, two and three vessel disease was 94%, 96% and 100%. The sensitivity for diagnosing disease in specific vascular territories was 91.6% for LAD 100% for RCA, 92.8% for CX and 100% for left main. CONCLUSIONS: Myocardial perfusion imaging with SPECT has high sensitivity for diagnosing coronary artery disease. The sensitivity and specificity were more accurate in proximal anterior descending artery disease, left main and three-vessel coronary artery disease. We found correlation in the site, number and severity of the angiographic lesions and in myocardial perfusion defects.