Relationship among epicardial coronary disease, tissue myocardial perfusion, and survival in heart transplantation.

BACKGROUND

Cardiac allograft vasculopathy continues to represent the major limitation to long-term cardiac allograft survival. Routine angiography and intravascular ultrasound fall short in their ability to detect microcirculatory aberrations. Thrombolysis in myocardial infarction (TIMI) myocardial perfusion grades (TMPG) have been used as a measure of microvascular circulation in patients treated for acute myocardial infarction. We studied the correlation of epicardial coronary anatomy with microvascular flow as determined by TMPG and correlated it with patient outcome.

METHODS

We enrolled 66 consecutive cardiac transplant recipients (49 men; mean age 52 +/- 13 years; range 15-70 years) undergoing surveillance coronary angiogram during a 9-month period. All angiograms were interpreted for epicardial coronary anatomy by an independent investigator. Another investigator, blinded for clinical data and angiogram interpretation, interpreted TMPGs. TMPG 0 was defined as no apparent tissue-level perfusion; TMPG 1 indicated presence of myocardial blush but no clearance from the microvasculature; TMPG 2 blush cleared slowly; and TMPG 3 indicated that blush began to clear during washout (blush is minimally persistent after 3 cardiac cycles of washout). Cardiac deaths served as the primary outcome variable.

RESULTS

Fifty-eight of 66 patients had an abnormal TMPG. Mean TMPG in all these patients was 4.2 +/- 3 (normal is 9). Forty-four patients (Group A) with no angiographic coronary narrowing had TMPG 4.81 +/- 3.1, and 22 patients (Group B) with epicardial coronary narrowing 40% of lumen diameter had TMPG 3.0 +/- 2.5 (p = 0.007). There was no difference in TMPG related to the coronary territory involved. At a mean follow-up of 30 +/- 2.5 months, 6 (13.6%) of 44 patients in Group A had died, and 7 (31.8%) of 22 in Group B had died (p < 0.03).

CONCLUSIONS

Microcirculatory aberrations as assessed by tissue TMPG is abnormal across all coronary territories in cardiac transplant recipients and associated with poor survival, suggesting a generalized microvascular involvement even in the presence of a normal angiogram. Patients with focal epicardial coronary narrowing have significantly greater decline in tissue perfusion, independent of the coronary territory involved, and exhibit poor survival compared with patients without epicardial coronary disease.