Answers and Case Discussion

Clifford's case happened in real life, and I'll tell you the outcome shortly. The real case was filled with the same ambiguities and tough decisions you faced in trying to decide proper management while reading the case. I hope every one got the first and second answers correct; Cliff had a normal axis and QRS duration, but dramatic evidence of acute inferior wall ST segment elevation infarction, including tall, peaked hyperacute T waves.

Question 3, of course, was aimed at reinforcing the concept that in the provider-patient encounter you can accomplish many things rapidly at the same time, and was aimed particularly at reinforcing the concept that you need to always keep the possibility of aortic dissection at the front of your mind when faced with a clinical STEMI and the potential for fibrinolysis.

The next narrative paragraph sets the stage for the most complex decision-making of the case and brings to the forefront some controversial issues. These issues include when patients with STEMI in community hospitals should be transferred to tertiary institutions for primary PCI, how far one should go in ruling out aortic dissection before committing to fibrinolyt-ics, and subjective decisions regarding the priority of beta blockers and nitroglycerin in patients with hypotension and slow heart rates. I will tell you now that a group of a dozen cardiologists would not all agree on the answers to some of the difficult questions that were faced with Cliff.

Cliff presented early, after only 20 min of pain. It took only 6 min from door time to make the diagnosis of STEMI. If a helicopter was ordered at that time it would take "scramble time" (perhaps 3 min) plus a 30 minute flight time to arrive at your facility. Another 10 min for loading, a return trip of 30min to the tertiary center, and 10 min to prep and gain catheter access would total approximately 80 min. If everything went perfectly smoothly, Cliff could perhaps have PCI accomplished in under the 90-minute period allotted to accomplish primary PCI in the ACC Guidelines.

However, with the opportunity to make a thrombolysis decision occurring at only 8 min after arrival, the staff was able to achieve a door to needle time of only 10 or 12min. Thus, choosing primary PCI would have created a time difference of approximately 70 min between opportunity for thrombolysis and opportunity for primary PCI, exceeding the 60 min advocated by the ACC Guidelines as being the maximum recommended time difference between thrombolysis and PCI. Cliff therefore received TNK in real life.

You will note that the decision to thrombolyse was made without benefit of a chest film. A chest X-ray, although useful if immediately available, is not required to rule out a dissection. Cliff did not relate the tearing kind of pain usually associated with dissection, it did not radiate to his back, and he had equal pulses bilaterally. Most authorities agree that this constitutes adequate clinical clearance for thrombolysis. Indeed, in the realm of prehospital thrombolysis, there is no radiologic imaging option. As is usually the case in medicine, you're playing the odds.

As is often typical with inferior STEMIs, Cliff had a heart rate in the high 50s and a BP of approximately 90. Nitrates and beta blockers would likely push Cliff's blood pressure down to undesirable levels, and his heart rate was already at levels usually achieved with beta blockers, so pain control was given the priority in question 5. Note that the morphine was given in a relatively small dose to try to avoid further hypotension. Also remember that when choosing between nitrates and beta blockers in acute coronary syndromes, greater value accrues to the beta blocker, and it should always be given priority over nitrates in patients with marginal blood pressures.

The next narrative paragraph tells us that Cliff's ST segments have come down 2.5 mm, or approximately 50% from their high of 5 mm in his initial

Figure 14.14.

ECG. In addition, his pain is much better. This constitutes provisional evidence of reperfusion.

Unfortunately, an episode of ventricular fibrillation ensues, and after a successful defibrillation, Cliff develops more pain and his ST segments return to nearly 5 mm. We must now conclude that Cliff has suffered a reocclusion despite thrombolysis. It is now time to move rapidly and aggressively to facilitate transport to a cath lab for rescue PCI.

That's exactly what happened to the real-life Cliff. Cliff had a 95% proximal RCA occlusion at the time of PCI. Happily enough, his post-PCI ECG in Figure 14.14 reflects resolution of ST changes, although Q waves are present in the inferior wall that suggest Cliff may still have lost some muscle.

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