Francisco José Rodríguez Rodrigo

Radionuclide studies in patients with stress-induced ST-segment elevation after acute myocardial infarction

The meaning of a stress-induced ST-segment elevation (delta ST) after acute myocardial infarction is still controversial. Some studies show it is related to asynergy, and other studies show it is related to ischemia. However, no study has compared the delta ST with both stress-induced ischemia and stress-induced asynergy in the same group of patients. With this purpose, 88 patients were studied 16 +/- 4 days after acute myocardial infarction. They were submitted to a dobutamine stress test on two different occasions 1 to 2 days apart. Dobutamine was infused up to 40 micrograms/kg/min with blood pressure and electrocardiographic controls. Thallium-201 single-photon emission computed tomography was performed during the highest dobutamine dose and 3 to 4 hours later. Equilibrium radionuclide ventriculography was performed at rest and during the highest dobutamine dose. Global and regional (hypokinetic area) ejection fractions were quantified. The ST segment was elevated > or = 1 mm in 33 patients at rest and in 71 during stress. A stress-induced delta ST was seen in 66 patients. Redistribution was detected in 65 patients. Multiple regression analysis showed a significant correlation between ST elevation and thallium defect score both at rest and during stress. No correlation was found between delta ST and redistribution score. However, a significant inverse linear correlation was found between the delta ST and the change in regional ejection fraction: the greater the delta ST, the smaller the change in regional ejection fraction with dobutamine. In conclusion, a stress-induced delta ST is not related to ischemia but to stress-induced left ventricular asynergy.

The dobutamine stress test with thallium-201 single-photon emission computed tomography and radionuclide angiography: postinfarction study.

OBJECTIVES The purpose of this study was to investigate left ventricular wall motion changes during dobutamine-induced myocardial ischemia. BACKGROUND Dobutamine is increasingly used as a stress test. It has been assumed that high doses of the drug induce the same changes in contractility as physical exercise. However, some data suggest that ischemic myocardium can respond to dobutamine with an increase in contractility. METHODS Sixty-three postinfarction patients twice underwent the dobutamine test (up to 40 micrograms/kg per min) within 1 to 2 days. Thallium-201 single-photon emission computed tomography (SPECT) and gated equilibrium radionuclide ventriculography were performed on each patient at rest and with dobutamine. Both global and regional ejection fractions were quantified. Sixty patients underwent coronary cineangiography within 1 week. The presence of redistribution was correlated with global and regional ejection fraction changes and with coronary lesions. RESULTS Redistribution was present in 45 patients, and no change or a decrease in global or regional ejection fraction was detected in 22. In the entire group of patients global ejection fraction increased from 46 +/- 12% to 56 +/- 14%. The six patients with triple-vessel disease had a flat (-0.2 +/- 5%) ejection fraction response to dobutamine, whereas the remaining patients had an increase of 11 +/- 7% (p = 0.003). The regional ejection fraction of the hypokinetic area increased from 27 +/- 10% to 41 +/- 19%, showing no change or a decrease in 13 patients. The 44 patients with peri-infarct redistribution had a significantly higher increase in regional ejection fraction than those without redistribution (16.4 +/- 10% vs. 4.7 +/- 17%, p = 0.003). In the patients with peri-infarct redistribution, an inverse linear correlation was found between redistribution score and dobutamine-induced regional ejection fraction change (r = -0.44, p = 0.004). CONCLUSIONS Mild to moderate dobutamine-induced peri-infarct ischemia is compatible with an increase in contractility, whereas severe ischemia induces worsening of wall motion.

Agenesia del tronco coronario izquierdo. Descripción de un caso y revisión de la bibliografía

Se describen los hallazgos clinicos y angiograficos de un varon de 55 anos de edad, con manifestaciones clinicas de cardiopatia isquemica de larga evolucion. Ademas de aterosclerosis coronaria grave, se evidencio una atresia congenita del tronco coronario izquierdo. Se describe la anomalia coronaria encontrada y se discuten su importancia y su significado.

Outcomes of patients at estimated low surgical risk undergoing transcatheter aortic valve implantation with balloon-expandable prostheses

INTRODUCTION AND OBJECTIVES Transcatheter aortic-valve implantation (TAVI) is an accepted treatment for patients with severe aortic stenosis and high surgical risk. However, there is lack in data about TAVI in low-risk patients that are already being treated with this therapy in some clinical contexts. METHODS A retrospective analysis of patients treated with transfemoral TAVI using Edwards Sapien prosthesis in one center was performed, classifying the patients into three groups according to the surgical risk (high/intermediate/low risk for STS score>8/4-8/<4). Clinical characteristics, procedure and follow-up outcomes were collected, comparing the results between low and high surgical risk groups. RESULTS 89 TAVIs using Edwards balloon expandable prosthesis were performed (9 Sapien XT and 80 Sapien 3 valves were implanted). 40 patients (45%) presented a STS score<4, while 33 (37%) had a STS>8. Low-risk patients were significantly younger and had lower rates of coronary artery disease, peripheral vascular disease, pulmonary lung disease and atrial fibrillation. There were no significant differences in most of the technical variables of the procedure, apart from vascular complications and complete left bundle branch block after valve implant, which were higher in the group with STS>8. Patients of low risk presented shorter hospital stay (2,91±1,6, vs 4,8±3,9 days), with lower rates of mortality at mid- and long follow-up (death from any cause 15,2% vs 0%, p 0,04). CONCLUSIONS TAVI in low-risk patients is safe and associated with better outcome at mid and long-term follow-up compared to high-risk patients.

Electrocardiographic changes and conduction disturbances after transfemoral aortic valve implantation with Edwards Sapien 3 prosthesis

OBJECTIVES The aim of this study is to describe electrocardiographic changes and conduction abnormalities in patients undergoing transcatheter aortic valve implantation (TAVI). METHODS 76 patients who underwent TAVI using Edwards Sapien 3 prosthesis were included, comparing electrocardiographic registries at admission, post-procedure and before discharge. RESULTS Patients after TAVI presented a longer PR interval, a wider QRS, and a longer corrected QT, with a left deviation of QRS axis and T waves; reversible changes that tended to correct in the following days after TAVI. Complete atrioventricular block incidence was 2.9%. New-onset left bundle branch block (LBBB) incidence was 39%, although solved in almost half of patients before discharge. CONCLUSIONS TAVI was associated with different reversible electrocardiographic changes that suggest a transient impact on the conduction system. One of every five patients presented permanent LBBB after valve implant.

Myocardial Infarction and 5,10-Methylenetetrahydro-folate Reductase Gene Mutation

A 40-year-old woman with previous venous thrombosis in the lower limbs had recurrent myocardial infarction in the early puerperium. The only documented risk factor was an elevated level of plasma homocysteine, associated to a heterozygotic anomaly in the enzyme responsible for its metabolism, 5,10-methylenetetrahydrofolate reductase. The case and approaches to treatment are discussed.