RESUMO
BACKGROUND: Left ventricle (LV) global longitudinal strain (GLS) at rest has shown prognostic value in patients (pts) with severe aortic stenosis (SAS). Contractile reserve (CR) during exercise stress echo (ESE) estimated via GLS (CR-GLS) could better stratify the asymptomatic patients who could benefit from early intervention. AIMS: To determine the long-term prognostic value of CR-GLS in patients with asymptomatic SAS with an ESE without inducible ischemia. Additionally, to compare the prognostic value of CR assessed via ejection fraction (CR-EF) and CR-GLS. METHODS: In a prospective, single-center, observational study between 2013 and 2019, 101 pts with asymptomatic SAS and preserved left ventricular ejection fraction (LVEF) > 55% were enrolled. CR was considered present with an exercise-rest increase in LVEF (Simpson's rule) ≥ 5 points and > 2 absolute points in GLS. Patients were assigned to 2 groups (G): G1: 56 patients with CR-GLS present; and G2: 45 patients CR-GLS absent. All patients were followed up. RESULTS: G2 Patients were older, with lower exercise capability, less aortic valve area (AVA), a higher peak aortic gradient, and less LVEF (71.5% ± 5.9 vs. 66.8% ± 7.9; p = 0.002) and GLS (%) at exercise (G1: -22.2 ± 2.8 vs. G2: -18.45 ± 2.4; p = 0.001). During mean follow-up of 46.6 ± 3.4 months, events occurred in 45 pts., with higher incidence in G2 (G2 = 57.8% vs. G1 = 42.2%, p < 0.01). At Cox regression analysis, CR-GLS was an independent predictor of major cardiovascular events (HR: 1.98, 95% CI 1.09-3.58, p = 0.025). Event-free survival was lower for patients with CR-GLS absent (log rank test p = 0.022). CR-EF was not outcome predictive (log rank test p 0.095). CONCLUSIONS: In patients with asymptomatic SAS, the absence of CR-GLS during ESE is associated with worse prognosis. Additionally, CR-GLS was a better predictor of events than CR-EF.
RESUMO
Introducción: El eco estrés evidencia la isquemia miocárdica como un trastorno regional y transitorio de la motilidad. El análisis visual es subjetivo y depende de la experiencia del operador, lo que ha motivado la búsqueda de un método semiautomático que permita minimizar esta limitación y así mejorar la confiabilidad y reproducibilidad de la prueba. Esto ha generado creciente interés en la introducción de la medición del strain longitudinal bidimensional antes del eco estrés y durante y después de él. Su determinación en las diferentes fases de apremio, en caso de que sea útil, permitiría reducir otras limitaciones, como la imposibilidad de alcanzar la frecuencia cardíaca submáxima, la dificultad de visualizar trastornos muy sutiles y el retraso en la adquisición de las imágenes, lo que incrementa los falsos negativos. Objetivos: Evaluar si el análisis del strain longitudinal realizado en reposo, cuando no hay evidencias de trastornos contráctiles visuales, es capaz de predecir el resultado del eco estrés y si el strain longitudinal basal es diferente en los pacientes con enfermedad coronaria significativa en comparación con los que no la presentan (en su evaluación previa al comienzo de la prueba). Material y métodos: Se compararon los resultados del strain longitudinal en reposo en 62 pacientes con eco estrés positivo incorporados en forma consecutiva en un período de 12 meses, a la mitad de los cuales se les realizó una cinecoronariografía (Grupo A) y a la otra mitad no se le efectuó este estudio (Grupo B) versus un grupo control (Grupo C) con prueba negativa y sin cinecoronariografía. Resultados: El strain longitudinal entre el Grupo A y el Grupo B no mostró diferencia estadística significativa (-21,8% ± 2,4% vs. -21,5% ± 2,5%), como tampoco el de los pacientes con prueba positiva (Grupo A + B) versus los controles (-21,67% ± 2,4% vs. 21,9% ± 2,8%). Conclusión: El strain longitudinal bidimensional no permitió predecir el resultado del eco estrés ni tampoco la presencia de enfermedad coronaria significativa en los pacientes que fueron sometidos a cinecoronariografía invasiva.
RESUMO
BACKGROUND: The determination of coronary flow reserve (CFR) is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD) coronary artery. METHODS: A total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography. RESULTS: The feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%). Mean CFR was 2.67 at de end of dobutamine test.There was an excellent concordance between delta HR (difference between baseline HR and maximum HR) and the increase in the CFR (correlation coefficient 0.84). In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%). In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99%) at 75% of their predicted maximum heart rate. CONCLUSIONS: We found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm from baseline HR or at least 75% of the maximum predicted heart rate to consider sufficient the test for the analysis of CFR.
