What is the mortality rate for cardiogenic shock complicating myocardial infarction? How should such patients be managed to improve outcome and wha

What is the mortality rate for cardiogenic shock complicating myocardial infarction? How should such patients be managed to improve outcome and what are the results?

The advent of the thrombolytic era has not altered the incidence or mortality rate for cardiogenic shock complicating myocardial infarction (MI). It still represents almost 10% of patients with MI, with almost 90% dying within 30 days.

Pooled results from retrospective, unrandomised data or historical reviews, which examined the effects of early revascularisation, have suggested reduced mortality following bypass surgery (CABG) or coronary angioplasty (PTCA) to 33%2 and 42% 3 respectively. Recently, a few randomised trials have attempted to compare such early (within 48 hours) revascularisation with a strategy of initial medical stabilisation. The latter might include thrombolysis, inotropic support and intra-aortic balloon pump counterpulsation (IABP), still with the option of delayed intervention. It is unfortunate that most of these studies have faltered on slow patient recruitment 4 leaving only one completed study (SHOCK, SHould we emergently revascularise Occluded Coronaries for Shock) to guide our management of these patients.

Over a 5 year period, the SHOCK trial randomised 302 patients to receive either early revascularisation within hours from randomisation, or initial medical stabilisation with the option of delayed intervention. Thirty day mortality was reduced in the early intervention group (46% vs 56%) with this benefit extending out to 6 months and particularly apparent in the younger (<75 years) age group. The low mortality in the control group is striking, and explains the lack of a large difference between the two groups. Nevertheless, it suggests benefit even with a relatively aggressive conservative policy in these patients.

Because of trial recruitment difficulties it is unlikely that further randomised data will emerge in the foreseeable future. Evidence from the SHOCK trial would seem to suggest that at present it would be reasonable to consider an aggressive approach with early revascularisation in patients with shock complicating myocardial infarction. However, access to surgery should be available – 36% of patients required this intervention rather than PTCA. Mean time to revascularisation was under hour in the trial, and quite how much later such benefit might extend is unclear. Care should include vigorous medical stabilisation in all such patients with thrombolysis, inotropes, balloon pumping and even ventilation if necessary with a view to late revascularisation (PTCA or CABG). In young patients early (<48 hours) revascularisation should be considered.