title: Low-Level Laser Application in the Early Myocardial Infarction Stage Has No Beneficial Role in Heart Failure.
abstract: Low-level laser therapy (LLLT) has been targeted as a promising approach that can mitigate post-infarction cardiac remodeling. There is some interesting evidence showing that the beneficial role of the LLLT could persist long-term even after the end of the application, but it remains to be systematically evaluated. Therefore, the present study aimed to test the hypothesis that LLLT beneficial effects in the early post-infarction cardiac remodeling could remain in overt heart failure even with the disruption of irradiations. Female Wistar rats were subjected to the coronary occlusion to induce myocardial infarction or Sham operation. A single LLLT application was carried out after 60 s and 3 days post-coronary occlusion, respectively. Echocardiography was performed 3 days and at the end of the experiment (5 weeks) to evaluate cardiac function. After the last echocardiographic examination, LV hemodynamic evaluation was performed at baseline and on sudden afterload increases. Compared with the Sham group, infarcted rats showed increased systolic and diastolic internal diameter as well as a depressed shortening fraction of LV. The only benefit of the LLLT was a higher shortening fraction after 3 days of infarction. However, treated-LLLT rats show a lower shortening fraction in the 5th week of study when compared with Sham and non-irradiated rats. A worsening of cardiac function was confirmed in the hemodynamic analysis as evidenced by the higher LV end-diastolic pressure and lower +dP/dt and -dP/dt with five weeks of study. Cardiac functional reserve was also impaired by infarction as evidenced by an attenuated response of stroke work index and cardiac output to a sudden afterload stress, without LLLT repercussions. No significant differences were found in the myocardial expression of Akt1/VEGF pathway. Collectively, these findings illustrate that LLLT improves LV systolic function in the early post-infarction cardiac remodeling. However, this beneficial effect may be dependent on the maintenance of phototherapy. Long-term studies with LLLT application are needed to establish whether these effects ultimately translate into improved cardiac remodeling.
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São PauloSão Paulo, Brazil; Laboratory of Cardiac Physiology, Federal University of São PauloSão Paulo, Brazil.
authors.forename: Martha T
authors.initials: MT
authors.lastname: Manchini
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Ednei L
authors.initials: EL
authors.lastname: Antônio
authors.affiliation: Medicine Program, Nove de Julho University São Paulo, Brazil.
authors.forename: José Antônio
authors.initials: JA
authors.lastname: Silva Junior
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Paulo de Tarso C
authors.initials: PT
authors.lastname: de Carvalho
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Regiane
authors.initials: R
authors.lastname: Albertini
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Fernando C
authors.initials: FC
authors.lastname: Pereira
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Regiane
authors.initials: R
authors.lastname: Feliciano
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Jairo
authors.initials: J
authors.lastname: Montemor
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São PauloSão Paulo, Brazil; Laboratory of Cardiac Physiology, Federal University of São PauloSão Paulo, Brazil.
authors.forename: Stella S
authors.initials: SS
authors.lastname: Vieira
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Grandinetti
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Amanda
authors.initials: A
authors.lastname: Yoshizaki
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Marcio
authors.initials: M
authors.lastname: Chaves
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Móises P
authors.initials: MP
authors.lastname: da Silva
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São Paulo São Paulo, Brazil.
authors.forename: Rafael do Nascimento
authors.initials: RD
authors.lastname: de Lima
authors.affiliation: Translational Physiology Laboratory, Brazil Physical Education and Aging Science Program, São Judas Tadeu University São Paulo, Brazil.
authors.forename: Danilo S
authors.initials: DS
authors.lastname: Bocalini
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Bruno L
authors.initials: BL
authors.lastname: de Melo
authors.affiliation: Laboratory of Cardiac Physiology, Federal University of São Paulo São Paulo, Brazil.
authors.forename: Paulo J F
authors.initials: PJ
authors.lastname: Tucci
authors.affiliation: Laboratory of Biophotonic, Nove de Julho University, São PauloSão Paulo, Brazil; Laboratory of Cardiac Physiology, Federal University of São PauloSão Paulo, Brazil.
authors.forename: Andrey J
authors.initials: AJ
authors.lastname: Serra
keywords: angiogenesis; cardiac performance; cardiac remodeling; low-level laser therapy; myocardial infarction