Edmonton, AB - A contemporary pharmacologic regimen delivered rapidly, coupled with a strategy of regimented rescue and routine coronary intervention within 24 hours, may give just as good results as timely expert PCI in the treatment of STEMI patients, according to the results of the Which Early ST-Elevation Myocardial Infarction Therapy (WEST) study.

The study, led by Dr Paul Armstrong (University of Alberta, Edmonton), was published online in the European Heart Journal on June 6, 2006.

Armstrong commented to heartwire: "We have shown in this study that in a country like Canada we can move to a prehospital setting for the initial management of STEMI patients and shorten the time to treatment, whatever that treatment is—thrombolysis or PCI. Instead of getting snarled up in whether the best approach is lysis or PCI, this study shows that either approach is fine if done fast, and in these circumstances actually there is not much to choose between PCI and intelligent lytic therapy. We've also demonstrated that nurses and paramedics can do the right thing in a prehospital setting with physician oversight."

The WEST study set out to evaluate whether optimal pharmacologic therapy at the earliest point of care was noninferior to expeditious primary percutaneous coronary intervention.

In the study, 304 STEMI patients within six hours of symptom onset all received aspirin and subcutaneous enoxaparin (1 mg/kg) and were randomized to one of three groups: tenecteplase (TNK) and usual care; TNK and mandatory invasive study within 24 hours; and primary PCI with 300-mg loading dose of clopidogrel. The protocol emphasized expedited care with ECG, randomization and therapy undertaken prehospital where possible, and direct communication to PCI teams to enhance their state of readiness.

Of the patients, 121 were actually randomized prehospital and 183 in the hospital. Time from symptom onset to treatment was short in all groups.

The authors point out that the prehospital approach led to faster treatment of PCI patients as well as those given lysis. "The overall median time from symptom onset to PCI in Group C was rapid at 176 minutes, but patients randomized prehospital received their PCI approximately one hour earlier than those randomized in hospital," they write. Of the Group B patients, 102 underwent cardiac catheterization within 24 hours, 89 of whom also received revascularization. Revascularization was also performed in 60 Group A patients.

No statistically significant differences were observed in the primary composite end point or any of its components—death, reinfarction, refractory ischemia, congestive heart failure, cardiogenic shock, or major ventricular arrhythmia at 30 days. However, there was a higher frequency of the combination of death and recurrent MI in Group A vs Group C.

The researchers note that, as expected, patients treated more quickly did better, with the primary efficacy end point occurring in 20.7% of patients who were randomized within two hours of symptom onset compared with 29.4% of those randomized after two hours (p=0.09). This was especially evident in the PCI group, where there was a twofold increase in the primary end point in patients randomized beyond two hours (16.4% vs 34.2%; p=0.052).

In an interview with heartwire, Armstrong stressed that group B in the WEST study was a very different strategy from the facilitated-PCI group in ASSENT-4, which did not show such good results. "While in ASSENT-4, PCI was done straight after lytic therapy in the facilitated group, the majority of patients in group B in WEST were not rushed to the cath lab immediately after lytic therapy; instead, PCI was generally performed sometime in the next 24 hours. I believe this may have produced better results, as it gives everything time to settle down and the procoagulant effect of the lytic to wear off." But Armstrong noted that those patients who were judged to need rescue PCI after the lytic (by the presence of continued symptoms or ECG changes) were taken to the cath lab quickly. "As long as these patients can be identified and acted on quickly, I think we have shown that there does not have to be a big panic about getting everyone else cathed straight away," he said.

"When we look at the results of both ASSENT-4 and WEST, I think we can tease out a good strategy involving thrombolysis and later intervention that represents an alternative to simply rushing everyone to immediate PCI, which will not be feasible for all patients," Armstrong commented. But he also says it may not be necessary to cath all patients routinely: "My view is that we should decide in a prehospital setting which strategy a patient will get—PCI or thrombolysis. If thrombolysis is the choice, it can be given then and there, and when the patient reaches the hospital it can be decided whether a rescue PCI is needed. Once we get over the rescue patients in the first 90 minutes, we should be able to selectively identify any other patients who may need to be cathed. The $64 000 question is, 'Are we smart enough to figure this out?' I think we are." He added: "I also believe that interventionalists ought to be able to sleep at night and be disturbed only for high-risk patients. Yes, we need interventionalists and we need to use them wisely and well for the right patients, but not necessarily for all patients."

But Armstrong commented that although this strategy appears to be very sensible, it does not look likely to happen routinely in the US, at least in the near future. "It appears that litigation issues about prehospital thrombolysis and the fact that the financial incentives for interventionalists to perform PCI are greater in the US will prevent such an approach from taking off there," he said.

Armstrong also believes that the prehospital approach is the way forward. "Prehospital care is being used in a number of countries, and they are leading the way. After the WEST study, we have now also started a prehospital approach to the care of MI patients, and it is working well," he commented.

Obviously, however, a 300-patient trial is not enough to convince everyone that this is the way to go. So Armstrong and colleagues are now planning a larger trial to test their group B arm vs routine primary PCI.