Abstract

This is a brief review of the modern management of unstable coronary artery disease, including acute myocardial infarction (AMI). During the past 50 years treatment of AMI has evolved from supportive care to therapeutic.In the 1970’s surgeons demonstrated that rapid reperfusion of the culprit coronary artery withemergency coronary artery bypass grafting(CABG) significantly reduced morbidity and mortality. With the evolution and adoption of percutaneous coronary intervention (PCI) to treat AMI, PCIhas become the standard of care for unstable coronary artery disease.

Introduction

Enhancements in the management of acute and chronic disease typically evolve over time. Sporadically, a quantum leap in the management of a life-threatening event can result in a significant improvement in outcomes.

In 1876 Adam Hammer [1] postulated that a myocardial infarction was instigated by the interruption of blood flow into a coronary artery. Notwithstanding Hammer’s advice the management of unstable coronary artery disease, (CAD), including acute myocardial infarction (AMI), was traditionally managed conservatively with therapies designed to treat symptoms and sequelae, but not the cause. Symptomatic management alone resulted in the in-hospital AMI mortality between 15-30 % with survivors demonstrating significant residual morbidities, and late mortality.

Methods and Materials

Our strategy was to treat the patient as a dire emergency. When a patient was suspected of having an acute coronary event demonstrated symptoms, EKG, and blood bio markers of AMI, they underwent emergency coronary angiography. The pre-op coronary angiogram typically demonstrated a total occlusion or a significant filling defect (clot) within the culprit coronary artery. At surgery, we routinely inserted a small balloon tipped catheter into that vessel to extract clot and, atherosclerotic debris, and routinely bypassed other vessels with significant angiographic lesions. The average time from admission to angiography and to CABG was typically under 2 hours from the time the patient arrived at our institution. Our gold standard that triggered this approach was continuing chest pain indicating myocardium still at risk, and not necessarily the time elapsed from the onset of chest main. If the patient was continuing to have chest pain, or its equivalent, beyond the “golden 6 hours, ruled out other causes such a pericarditis.

Discussion

The modern era of cardiac surgery was ushered in with the development of the heart-lung machine [2]. The 1960’s and beyond saw significant refinements in coronary artery bypass surgery (CABG) [3]. These advances ushered in at first, the era of surgical management of chronic, stable coronary artery disease CAD, then evolved into the surgical management of unstable CAD [4,5].

During the mid 1970’s, the conventional management for AMI made the quantum leap from treating symptoms and sequelae, to treating the cause. The cause, first postulated by Hammer a century earlier, was confirmed in the 1970’s as the sudden occlusion of a coronary artery by a clot generated from a ruptured atherosclerotic plaque. Reports published by Berg [5] et al., and this author [6,7] demonstrated that the rapid reestablishment of blood flow into the culprit artery with CABG resulted in a significant reduction of morbidity and mortality as compared to conventional, symptomatic, management. Emergency reperfusion using CABG as a treatment of AMI reduced the in-hospital mortality in my institution from approximately 29% to 1.3%, with a 1-year mortality of 2.8%.

Though some in the literature expressed doubtas to the efficacy of emergency CABG [8] we and others continued treating AMI as an extreme emergency analogous to a gunshot wound of the abdomen, or an aortic rupture. Emergency CABG reintroduces blood flow into the occluded AMI vessel, salvages myocardium, improves myocardial function, and permits the bypassing of other diseased coronary arteries. The revelation that an occlusive clot, generated from a ruptured plaque, predated but paved the way for thrombolytic and PCI therapies. PCI [9] is today’s accepted and preferred standard of care for the entire spectrum of CAD, including unstable CAD and AMI, and is one of the most commonly performed medical interventions.

Conclusion

The concept of timely reperfusion is central to the modern treatment of CAD. As a general rule, the initial therapy for AMI is directed toward restoration of perfusion into the culprit coronary artery with the goal to salvage jeopardized myocardium. This may be accomplished through thrombolysis, PCI, or CABG surgery alone or in combination.

References

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