Comparison of left ventricular function and contractile reserve after successful recanalization by thrombolysis versus rescue percutaneous transluminal coronary angioplasty for acute myocardial infarction

Abstract

To determine how coronary reperfusion affects rest and exercise ventricular function after acute myocardial infarction (AMI), 63 patients with a patent infarct artery after intravenous thrombolytic therapy (lysis) were compared with 27 patients who failed thrombolysis but had successful acute recanalization by percutaneous transluminal coronary angioplasty (PTCA) as a “rescue” procedure. Contrast ventriculography was performed acutely and on day 7. Resting radionuclide ventriculography was performed at 24 hours and repeated with exercise on day 30. There were no differences in global ejection fraction (EF) between the 2 groups during acute contrast ventriculography. However, by 24 hours, the EF had deteriorated in the rescue group (40 ± 17 vs 49 ± 11% in the lysis group, p ≤ 0.05). No improvement occurred in either group on day 7. By day 30, an improvement in resting radionuclide EF 5.9 ± 1.9% occurred in rescue patients and the difference between rescue and lysis groups was no longer significant (46 ± 14 vs 50 ± 11%, p = 0.12). A normal (≥ 5%) increase in EF with exercise occurred in 64%, with either normal or exercise-enhanced regional wall motion present in 67% of patients. A significant increase in EF occurred within the rescue group, from 46 ± 14% at rest to 50 ± 15% at peak exercise (p ≤ 0.0005). The EF increased with exercise from 50 ± 11 to 58 ± 15% in the lysis group (p ≤ 0.0001). With equivalent workloads, the lysis group had a significantly greater EF response to exercise compared with rescue patients (7.5 ± 7.5 vs 3.8 ± 4.7%, p < 0.02). Despite successful acute recanalization in all patients, differences in ventricular function were apparent including: (1) greater preservation of ventricular function at 24 hours in patients with successful thrombolysis; (2) late improvement in resting EF with rescue PTCA; and (3) greater contractile reserve in patients with successful thrombolytic reperfusion. These data suggest that full recovery of myocardium may not be accurately assessed with a predischarge resting ventriculogram. Aggressive revascularization with thrombolysis or PTCA (or both) resulted in a normal EF response to exercise after AMI. Although successful thrombolytic reperfusion appears to be the most beneficial regimen, rescue PTCA may also be a viable strategy resulting in late improvement in EF and maintenance of EF response to exercise.