Non-invasive hemodynamic evaluation of patients with LV dysfunction and intractable dyspnea with first pass radionuclide angiography: comparison with echocardiography

Abstract

Introduction: Advanced heart failure is characterized by recurrent episodes of dyspnea with or without obvious signs of congestion and fluid retention. These patients have many potential cardiac and pulmonary causes for recurrent dyspnea and repeating an echo each time is often uninformative and frequently limited technically in CHF patients, particularly if significant pulmonary disease also exists. We therefore sought to use first pass radionuclide angiography (FPRNA) to non-invasively evaluate the hemodynamic status of these very symptomatic and failing patients. Methods: Consecutive patients with LV dysfunction and severe dyspnea underwent upright FPRNA after injection of 15-45 millicurie of sestamibi. Imaging was performed using a Sim-400 multicrystal camera. All hemodynamic data were based on acquired raw and derived data. Included patients also underwent echocardiography which was independently reviewed. Results: 52 patients (80% male) met criteria. Mean age 68.7 years. Mean LVEF by echo 29.7% and 32.2% by FPRNA (NS p=0.53). Mean RVEF by FPRNA was 43.85%. 65% had RVEF <40%. Peak LV filling was 1.41 +/− 0.58 (normal value is >2.5), suggesting marked diastolic dysfunction. Mean cardiac output was 6.2 and mean index was 3.2. The LV was markedly enlarged in this population reflecting advanced heart disease. Mean LV end diastolic volume was 230 cc and end systolic volume was 162cc, both values over twice the accepted normal range. 69.2% had MR by echo (21.2% were rated as 1+, 13.5% as 2+, 17.3% each as 3+ and 4+). Most importantly, the normalized mean pulmonary transit time (corrected for heart rate) was found to directly correlate with the degree of MR on echo (Spearman's rho 0.346, p=0.02). This has not been previously shown in severe CHF. Conclusion: In this study we sought to establish that reliable non-invasive hemodynamic data can easily be obtained from very symptomatic patients with LV dysfunction. The advantages of FPRNA are that patients are imaged upright and the results are quantitative. Accurate evaluation of MR is possible by normalizing the PMTT, thereby allowing this normally subjective echo data to be quantified and followed serially. In addition quantitative data on LV and RV systolic function, LV diastolic function and pulmonary circulation can be obtained and followed serially. By comparing such serial results, abnormalities in specific parameters may yield clues to whether dyspnea is of cardiac or pulmonary origin in severe CHF.