Comparing changes in severe versus mild perfusion defect size in patients who underwent serial rubidium-82 positron emission tomography myocardial perfusion imaging

The reproducibility and prognostic value of serial measurements of heart rate response to regadenoson during myocardial perfusion imaging

PURPOSE

The heart rate response (HRR, percentage change from baseline) to regadenoson during myocardial perfusion imaging (MPI) can provide incremental prognostic value in patients with known or suspected coronary artery disease. Our purpose was to evaluate the variability and prognostic value of HRR on serial measurements.

METHODS

We studied 648 consecutive patients (61 ± 11 years, 48 % with diabetes) who underwent two regadenoson MPI studies (16 ± 9 months between studies). HRR <30 % was defined as abnormal. All-cause mortality was determined by chart review and verified using the US Social Security Death Master File.

RESULTS

HRR was well correlated between the two studies (intraclass correlation coefficient 0.72, 95 % CI 0.67 - 0.76) with no systematic bias (mean difference 0.88 %, p = 0.2) or proportional bias (p = 0.5) by Bland-Altman analysis in all patients and in those with normal MPI on both studies. Of the 308 patients (48 %) with normal baseline HRR (HRR-1), 33 % had developed a blunted HRR on the second MPI study (HRR-2). Older age, male gender, end-stage renal disease, and abnormal baseline left ventricular ejection fraction were independent predictors of a new-onset abnormal HRR. During a mean follow-up of 2.4 ± 1.2 years, 55 patients (8.5 %) died. Patients with a blunted HRR-1 had increased mortality risk irrespective of their HRR-2 (p = 0.9, log-rank test). Among patients with normal HRR-1, a blunted HRR-2 was an independent predictor of all-cause mortality beyond clinical and traditional MPI data (hazard ratio 2.83, 95 % CI 1.14 - 7.03). Finally, patients with a normal HRR-1 and HRR-2 had the lowest event rate, while those with any abnormal HRR had an increased risk of death (hazard ratio 2.5, 95 % CI 1.2 - 5.4).

CONCLUSION

There was good correlation in the HRR to regadenoson on serial measurements without systematic or proportional biases. Patients with consistently normal HRR had the best prognosis.

Uncontrolled risk factors and worsening perfusion pattern on SPECT myocardial perfusion imaging in medically treated patients with stable chronic ischaemic heart disease

PURPOSE

Few data exist on the correlation between the effectiveness of risk factor control and the evolution of myocardial perfusion over time in patients with stable ischaemic heart disease. The aim of the study was to evaluate the changes in stress-rest myocardial perfusion in medically treated patients with stable chronic ischaemic heart disease and the relationship with risk factor control.

METHODS

The study cohort included 174 consecutive patients (age 60 ± 9 years, 68 % men) undergoing stress-rest myocardial perfusion imaging (MPI) (study 1), who also underwent repeat evaluation (study 2) and who were clinically stable on medical therapy. Summed stress, rest and difference scores were calculated. According to the evolution of perfusion pattern from study 1 to study 2, patients were classified as improved, stable or worsened.

RESULTS

Study 2 was performed on average 2.7 years after study 1. Of the 174 patients, 47 (26.9 %), 53 (30.8 %) and 74 (42.5 %) were classified as stable, improved and worsened, respectively. A significant trend was observed between the number of risk factors at the time of study 1 and worsening of myocardial perfusion (24 % of patients with zero or one risk factor showed worsening, 31 % with two, and 59 % with three or more; p = 0.03). Moreover, patients with worsened perfusion had a higher number of poorly controlled risk factors.

CONCLUSION

Despite medical therapy and clinical stability, myocardial perfusion worsened in 42.5 % of patients. The risk profile was reclassified in half of the patients. Worsening occurred more frequently in patients with three or more risk factors at the time of study 1 and in those with poorly controlled risk factors at the time of study 2; in this subset of patients, even if clinically stable, reassessment after 2 years could be considered.