Spontaneous delayed recovery of perfusion and contraction after the first 5 weeks after anterior infarction. Evidence for the presence of hibernating myocardium in the infarcted area.

Abstract

After anterior Q-wave infarction, the recovery of perfusion and wall motion may continue well after the subacute phase. Several patients exhibit relative hypoperfusion in viable tissue as late as 5 weeks after infarction, and a significant improvement of perfusion in the infarcted area commonly is observed between 5 weeks and 7 months. This delayed improvement of perfusion is associated with a delayed improvement of contractile function in the infarcted area after the first 5 weeks, which may continue for up to 7 months, suggesting the presence of hibernating myocardium in the infarcted area. Despite similar perfusion defect sizes, the level of regional function can be different at 5 weeks, and measurements taken around this time may not accurately estimate the eventual recovery of function.

Relationship between infarct size and severity measured by gated SPECT and long-term left ventricular remodelling after acute myocardial infarction

“…This study confirms that in patients submitted to successful PCI a spontaneous reduction in infarct size occurs beyond the 1-month evaluation. These findings are in agreement with previous studies reporting a significant late reduction in defect size in paired sestamibi SPECT studies performed early and a few months after AMI in patients treated conservatively or by thrombolysis [6,24,25]. Various mechanisms might play a role in this delayed perfusion improvement.…”

“…Therefore, we were unable to confirm the cardiac magnetic resonance data showing that patients with LV remodelling had substantially larger infarct resorption compared with patients without remodelling [8]. Conversely, our study demonstrates that the reduction of infarct size beyond the subacute phase may occur in all patients, in agreement with prior scintigraphic reports [6,24,25]. This means that infarct resorption could be a spontaneous event occurring after AMI independently of its size and of the patients' outcome [26,27].…”

“…Subjects with a history of prior infarction as well as patients with suboptimal PCI results were not considered; therefore, our observations might not apply to those patients. Finally, perfusion recovery at the follow-up study could be at least in part a consequence of functional improvement, even if there is evidence from previous reports that a delayed perfusion recovery occurs in a significant number of patients after PCI [6,24,25]. However, the decrease in infarct size observed in patients with LV remodelling suggests that functional improvement is not the sole determinant of perfusion changes at follow-up.…”

Changes in the response of hibernated myocardium to inotropic stimulation after angioplasty: A doppler myocardial imaging study

“…In the other studies, slight improvement following revascularization was noticed even months after the procedure. [20][21][22] Similar observations concerning contractility at rest were made based on the analysis of systolic velocity in CDMI studies. A detected mild increase of velocities directly after angioplasty without any further improvement parallels the observed relatively small improvement of global contractility at rest.…”

Relationship of infarct size and severity versus left ventricular ejection fraction and volumes obtained from 99mTc-sestamibi gated single-photon emission computed tomography in patients treated with primary percutaneous coronary intervention

“…To our knowledge, however, a comparison of infarct size and LVEF assessed using gated SPECT has not previously been reported. Moreover, scanty data are available on the relationship between infarct severity and LV function and volumes, particularly in patients submitted to early reperfusion therapy [17,25,26]. The aim of the present study was to evaluate the relationships of infarct size and severity with LVEF and LV volumes, all obtained from a single gated SPECT study, and to examine which factors influence these relationships in patients submitted to successful primary percutaneous coronary intervention for acute myocardial infarction.…”