Download Prognostic Value of Myocardial Perfusion Imaging In Patients

1859
Prognostic Value of Myocardial Perfusion Imaging In Patients Referred for Renal Transplant
Assessment
Prof. Sunil Bhandari, Dr Ann Tweddel, Dr David Eadington, Prof Andrew Clark, Dr Graham Wright, Mr Manos
Papodopolous
Hull and East Yorkshire NHS Trust
Introduction - Renal transplantation significantly reduces morbidity and mortality in patients with end stage renal
failure, and is the treatment of choice for patients considered fit enough for surgery. Pre-transplant cardiovascular
(CV) assessment aims to identify those at high risk of peri-operative cardiac events, to ensure that treatment is
optimised prior to surgery. It may also identify a subset of patients with poor CV prognosis that renal transplantation
would not improve their quality or quantity of life. Screening strategies vary widely. Myocardial Perfusion Imaging
(MPI) provides incremental prognostic information in patients with renal failure but its role as a risk stratification tool
prior to transplantation remains unclear. We conducted a retrospective review to assess the prognostic value of a
standardised dobutamine stress MPI protocol at a large tertiary UK centre.
Methods - A hand search was undertaken of all MPI scan reports performed between January 2005 and July 2012.
Details of baseline demographics, co-morbidities, medication history, dialysis modality, transplant status and
outcomes (death, myocardial infarction, stroke, heart failure hospitalisation) were obtained from clinic and discharge
letters stored on Patient Centre electronic database. Original myocardial perfusion scan and ECG data were reexamined, and relevant data from stress testing, perfusion imaging and gated left ventricular function assessment were
recorded. Analysis was performed using Kaplan Meier for all cause mortality and cardiac events according to scan
findings in addition to univariable analysis with Cox-proportional hazards to test for an association between
clinical/scan variables and both all-cause mortality, and combined all-cause mortailty and CV events. Results are
expressed as hazard ratio (HR) and 95% confidence intervals (CI).
Results - 138 scans were identified that had complete follow up data. 130 (94%) received dobutamine stress, all were
imaged with Technetium 99m sestamibi. 46 (33.3%) underwent renal transplantation, 49 were active or currently
suspended on the transplant waiting list (35.5%), 43 (31.2%) were deemed unsuitable for renal transplantation. During
a median follow up of 40.4 months, 22 patients died, and there were 11 confirmed cardiovascular events (6
myocardial infarctions, 4 strokes, 1 heart failure hospitalisation). There was no significant difference between the four
groups (normal study, fixed defects, reversible defects and small vessel disease) and either mortality (p =0.54), or
mortality and CV events combined (p=0.35).
Outcome
All-cause mortality
Analysis
Univariable
Multivariable
All cause mortality + CV events
Univariable
Multivariable
Predictors (Hazard ratio, 95% Confidence Interval)
Abnormal baseline ECG (2.32, 1.04-5.18)
Sum rest score
(1.221, 1.05-1.41)
Decision to transplant
(0.202, 0.07-0.61)
Abnormal ECG
(16.17, 3.5-74.72)
Sum rest score
(2.33, 1.35-4.02)
Decision to transplant
(0.1, 0.28-0.037)
Change in left ventricular systolic volume ( 0.906, 0.8480.968)
Abnormal baseline ECG (2.6, 1.24-5.44)
QRS duration
(1.02, 1.00-1.043)
Transplant indication
(2.63, 1.11-6.21)
Decision to transplant
(0.53, 0.33-0.86)
Sum rest score
(1.19, 1.03-1.38)
Abnormal baseline ECG (3.412, 1.32-8.84)
Table 1 – Predictors of mortality and mortality + CV events
Conclusions - High sum rest scores typically indicate prior myocardial infarction, and this was independently
associated with higher mortality in our cohort. Increased left ventricular end systolic volume on stress compared to
rest images is likely to be secondary to subendocardial ischaemia due to either multi-vessel coronary disease or
significant hypertension. It is a poor prognostic marker in the general population, but this is the first study to our
knowledge that demonstrates its prognostic value in potential renal transplant patients. The presence of reversible
ischaemia was not associated with worse outcomes, which is in contrast to other studies. This may be because these
patients had their risk modified through intensified pharmacotherapy and/or revascularisation. The relatively low CV
event rate in our cohort may also have meant that there was insufficient power to detect a true difference. The
presence of an abnormal ECG was strongly associated with both mortality and CV events; it may therefore be a useful
initial screening tool to identify patients that require further cardiac investigation.