Ventricular assist device therapy in post-cardiotomy cardiogenic shock: historical outcomes and current trends

Abstract

Ventricular assist device (VAD) therapy has been used successfully as a bridge to recovery, bridge to transplant and in the last decade as a destination therapy. The use of VAD for post-cardiotomy cardiogenic shock (PCCS) is not currently reported in national databases in the UK and Ireland. Data were collected through a telephone survey of chief perfusionists from all the cardiac surgery units in the UK and Ireland between October 2007 and October 2008. Approximately 28 000 adult cardiac surgical procedures were performed at 45 cardiac centres, of which 33 (73%) reported using VAD. The total number of patients supported was 66, of which 41% (n = 27) survived to be discharged home. About 42.5% (n = 28) died during VAD in place, and 16.5% died after successful weaning from VAD. Preferences for device types were Biomedicus (n = 25), Levitronix (n = 10), Sorin (n = 3), roller pump (n = 3) and Berlin heart (n = 2). Despite the reasonable survival rates after VAD use in post-cardiotomy heart failure, there are significant differences in their availability and individual's attitude towards their use. VAD use in PCCS should be prospectively documented in the audit returns of all the units, for further analysis and for generation of protocols.

INTRODUCTION

Ventricular assist device (VAD) has been used as a bridge to recovery, bridge to transplant and in the last decade as a destination therapy. Its initial use was associated with 75% mortality in the setting of post-cardiotomy cardiogenic shock (PCCS). But it has been used recently with improved survival. PCCS is observed in patients having surgery under cardiopulmonary bypass, most commonly as a result of myocardial stunning or hibernation. It occurs in 2–6% of all cardiac surgical procedures. Because of worsening risk profile of current cardiac surgical patients, increasing number of patients may be requiring pharmacological and mechanical support peri-operatively. Mean logistic EuroSCORE of patients operated in-house has increased from 5.5% in 2003 to 8.4% in 2008 in our department. Most of the cases respond to conventional pharmacological and mechanical support, i.e. intra-aortic balloon pump; however, there are cases in which myocardial recovery is refractory to these measures and would require additional mechanical support. Survival with VADs was reported to be <25% in studies carried out more than 10 years ago [1]. However, there have been significant advances in VAD technology and experience, and some subsequent studies have reported better outcomes, with up to 60% survival to discharge [2]. PCCS can be reversible with mechanical support, which in the form of VAD is a resource-intensive undertaking. The decision to insert a VAD can be difficult and is influenced by expected outcomes and patient and family wishes; however, this patient population has nearly 100% mortality unless treated by mechanical support, which offers the only hope of survival. Because of lack of information about VADs’ use in PCCS from Europe, we aimed to find out the current practice in the UK and Ireland, especially incidence of VAD implantation for PCCS, types of VADs used, their availability and outcomes in this specific scenario.

MATERIALS AND METHODS

Data were collected through a telephone survey of all the chief perfusionists from all the cardiac surgical units in the UK and Ireland from October 2007 to October 2008. Data collected include the total number of procedures carried out and the number of patients requiring VAD implantation for PCCS. Information about the availability of VAD, type of VAD used, availability of policy of VAD use and availability of finance for the use of VAD was obtained. Furthermore, information about the individual surgeon's concerns and attitude towards VAD therapy in PCCS was obtained.

Patient population

The study population consisted of all patients undergoing coronary artery bypass grafting and/or valve surgery between October 2007 and October 2008 who required implantation of VAD after surgery. Patients who underwent cardiac transplantation during the same hospital stay were excluded.

RESULTS

Incidence of post-cardiac surgery ventricular assist device implantation

All cardiac surgical units were contacted (n = 45) and 33 units (73.3%) reported to have used VAD for PCCS in the last calendar year. A total of 66 VADs were implanted, out of 28 000 cardiac surgical procedures performed in that year. Overall, the percentage of cardiac surgical procedures requiring VAD implantation for PCCS was (0.24%) small, but the incidence of VAD implantation is similar to that in USA quoted at 0.3% [3].

Ventricular assist device types, availability and use

Biomedicus was used in 53% of units, making it the most commonly used pump followed by Levitronix, which was used in 22% of units. Most of the VADs used were to support left ventricle (n = 32, 48.4%), followed by right VAD (RVAD) (n = 19, 28.7%) and then biventricular assist device (BIVAD) (n = 15, 22.7%). VAD was not used in 12 units (26.6%), and out of those 12 units, only 2 units (4.4%) did not have VAD available. In the remaining 10 units, surgeons were convinced that it is not a good therapeutic option for PCCS. The availability of funding was patchy across the UK and Ireland, with only eight units (17%) funded for VAD use in PCCS. Policy of VAD use in PCCS was in place in only 13 units (28%) because of unavailability of VAD, funding issues and surgeons’ belief that it is futile.

Outcomes

A total of 66 patients were supported with VAD therapy from October 2007 to October 2008. Out of those, 27 patients (41%) survived to be discharged home, as shown in Fig. 1. Twenty-eight patients died with VAD support in place and 11 died after successful weaning from VAD, making them as potential survivors.

Figure 1:

Survival of 41% is probably related to improved VAD technology and peri-operative management.

DISCUSSION

PCCS refractory to conventional treatment modalities carries nearly 100% mortality. Initial studies were less encouraging with a quoted mortality of 25%, which is a slightly pessimistic approach to the scenario in which nearly 100% of these patients would die without surgical intervention. A recent study by Hernandez et al. showed significantly improved survival with VAD therapy from USA, which may possibly be explained by improvements in VAD technology and also by improvements in the post-operative care.

We found varying attitudes of different surgeons, patchy availability of finances and lack of nationwide policy in the UK and Ireland, despite improved outcomes with VAD therapy in these patients.

Our study, with its inherent limitations, would suggest an encouraging survival rate of around 40%. The role of VAD in PCCS should be analysed prospectively and accurate data collected in the form of audit returns of all the units in the database, so that a regional experience can be built and a uniform policy of use can be implemented across the UK. Lack of joint policy of use is making this group of patients vulnerable to the individual surgeon's attitude and inequality of healthcare delivery.

Survival will hopefully improve even further with advances in policies of care, VAD technology and good patient selection. There is also a need for implementation of protocols used in centres of excellence around the globe, especially in the USA, which may improve outcomes in our region.

Literature review

Medline searched using the PubMed interface VAD, PCCS and survival in English literature. Related articles and references were screened (Table 1).

Table 1:

VAD use for PCCS with improving results

Article	Year of publication	Duration	No. of patients	Mean age	Type of devices used	No. of support days	All weaned from VAD	Weaned and discharged
Pae et al.	September 1992, J Thorac Cardiovasc Surg	1985–1990	965	56	Pneumatic 272, Centrifugal 559, LVAD 494, RVAD 121, BIVAD 350	3.9	45% (n = 434.25)	24% (n = 234.5)
Guyton et al.	August 1993, Ann Thorac Surg	1987–1991	31	58	Pneumatic, BIVAD 60%, LVAD 38%, RVAD 2%	4.7	55% (n = 17)	29% (n = 9)
Hernandez et al. [3]	July 2007, Circulation	1995–2004	5735	63	Pneumatic/electric	NA	NA	54%

Study limitations

1. It is a small and retrospective study but the only one of its nature from European centres.

2. Our data were limited to the information available to chief perfusionists, and also limited information can be exchanged over the phone.

CONCLUSION

Survival is suggested to be improving with VAD in PCCS, probably because of advances in VAD technology and improvements in peri-operative medical management. There should be uniformity in approaches towards VAD therapy and availability of finances to different units across the region. There is a strong demand for establishing VAD registry, from which prospective and accurate data can be collected for further analysis and generation of protocols.