Diastolic Dyssynchrony in Acute ST Segment Elevation Myocardial Infarction and Relationship with Functional Recovery of Left Ventricle

Longitudinal evaluation of diastolic dyssynchrony by SPECT gated myocardial perfusion imaging early after acute myocardial infarction and the relationship with left ventricular remodeling progression in a swine model

BACKGROUND

Left ventricular diastolic dyssynchrony (LVDD), a dyssynchronous relaxation pattern, has been known to develop after myocardial damage. We aimed to evaluate the dynamic changes in LVDD in the early stage of acute myocardial infarction (AMI) by phase analysis of 99mtechnetium methoxyisobutylisonitrile (99mTc-MIBI) single-photon emission computed tomography (SPECT) gated myocardial perfusion imaging (GMPI) and explore its relationship with the progression of left ventricular remodeling (LVR).

METHODS

The left anterior descending coronary arteries of 16 Bama miniature swine were occluded with a balloon to build AMI models. Animals were imaged by SPECT GMPI before AMI and at 1 day, 1 week and 4 weeks after AMI, and quantitative analysis was performed to determine the extent of left ventricle (LV) perfusion defects, left ventricular systolic dyssynchrony (LVSD) and the LVDD parameters: phase histogram bandwidth (PBW) and phase standard deviation (PSD). Echocardiography was simultaneously applied to evaluate left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), and the LVDD parameters: Te-12-diff and Te-12-SD. Myocardial injury markers were measured, and 12-lead ECGs were performed. The degree of LVR progression was defined as ΔLVESV (%) = (LVESVAMI4weeks - LVESVAMI1day)/LVESVAMI1day.

RESULTS

Thirteen swine completed the study. LVDD parameters changed dynamically at different time points after AMI. LVDD occurred as early as 1 day after AMI, peaked at 1 week, and trended toward a partial recovery at 4 weeks. Phase analysis on SPECT GMPI showed a significant correlation with tissue Doppler imaging for the assessment of LVDD during the longitudinal evaluation (r = 0.569 to 0.787, both P <0.05). During the univariate and multivariate regression analyses, the LVDD parameters PBW and PSD as of 1 day after AMI were significantly associated with the progression of LVR, respectively (PBW, β = 0.004, 95% CI 0.001 to 0.007, P = 0.024; PSD, β = 0.008, 95% CI 0.000 to 0.017, P = 0.049). Adjusted smooth curve fitting and threshold effect analysis indicated PBW and PSD break-point values of 142° and 60.4°, respectively, to predict the progression of LVR after AMI.

CONCLUSIONS

Phase analysis of SPECT GMPI can accurately and reliably characterize LVDD. LVDD occurred on the first day after AMI, reached its peak at 1 week, and partially recovered at 4 weeks after AMI. LVDD as evaluated by phase analysis of SPECT GMPI early after AMI was significantly associated with the progression of LVR. The early assessment of LVDD after AMI may provide helpful information for predicting the progression of LVR in the future.

Left atrial volume index and pulmonary arterial pressure predicted MACE among patients with STEMI during 8-year follow-up: experience from a tertiary center

BACKGROUND

It is important to identify patients that are at high risk following primary percutaneous coronary intervention (P-PCI) for the treatment of ST-segment elevation myocardial infarction (STEMI). Left ventricular ejection fraction (LVEF) is the most important parameter obtained from transthoracic echocardiography (TTE) for risk stratification. The authors evaluated the value of pulmonary artery pressure (PAP) and left atrial volume index (LAVI) for the prediction of major adverse cardiovascular events (MACE) in patients with STEMI that underwent P‑PCI.

METHODS

A total of 92 patients that underwent P‑PCI for STEMI were included in the study. All patients underwent TTE examination before discharge. The composite primary outcome of the study was all-cause mortality and new onset heart failure (HF) during an 8-year follow-up period.

RESULTS

The mean age of patients was 61.6 ± 12.4 years and 15 were female (16.3%). Major adverse cardiovascular events (MACE) defined as all-cause mortality and new onset HF occurred in 30 (41%) patients during a mean of 6 ± 2.7 years of follow-up. In the backward multivariate Cox regression analysis LVEF (odds ratio [OR] = 0.933, 95% confidence interval [CI]: 0.876-0.994, p = 0.031), LAVI (OR = 1.069, 95%CI: 1.017-1.124, p = 0.009), PAP (OR = 1.137, 95% CI: 1.057-1.223, p = 0.001) and creatinine level (OR = 1.730, 95% CI: 1.350-1.223, p = 0.029) were found to independently predict MACE during long-term follow-up. Receiver operating characteristic (ROC) curve analysis was performed, revealing that sPAP >24.5 mm Hg had a sensitivity and specificity of 72 and 66%, respectively; LAVI >31 ml/m² had a sensitivity and specificity of 72.2 and 83.3%, respectively.

CONCLUSION

In patients that underwent P‑PCI for the treatment for STEMI, LVEF, LAVI, PAP and creatinine level independently predicted all-cause mortality and new onset HF during long-term follow-up.

Diastolic dyssynchrony and its exercise-induced changes affect exercise capacity in patients with heart failure with reduced ejection fraction

BACKGROUND

Left ventricular diastolic dyssynchrony is common in patients with heart failure with reduced ejection fraction (HFREF). Little is known however, about its pathophysiology and clinical effects. Herein is hypothesized that presence of diastolic dyssynchrony at rest or at exercise may importantly contribute to HF symptoms. The aim was to investigate the influence of diastolic dyssynchrony and its exercise-induced changes on exercise capacity in HFREF patients.

METHODS

Patients with stable, chronic HF, left ventricular ejection fraction < 35%, sinus rhythm and QRS ≥ 120 ms were eligible for the study. Rest and cyclo-ergometer exercise echocardiography were performed. Diastolic dyssynchrony was defined as opposing-wall-diastolic-delay ≥ 55 ms measured in tissue-Doppler imaging. Exercise capacity was assessed by peak oxygen consumption (VO2peak). Association between diastolic dyssynchrony and VO2peak was assessed in univariate regression analysis and further adjusted for possible confounders.

RESULTS

Fourty eight patients were included (aged 63.7 ± 12.2). Twenty-seven (56.25%) had diastolic dyssynchrony at rest and 13 (27%) at exercise. Twenty-two (46%) experienced a change in diastolic dyssynchrony status during exercise. In univariate models diastolic dyssynchrony at rest or at exercise were associated with lower VO2peak (beta coefficient = -3.8, p = 0.004; beta coefficient = -3.6, p = 0.02, respectively). However, the ability to restore diastolic synchronicity during exercise was associated with higher VO2peak (beta coefficient = 3.4, p = 0.04) and remained an important predictor of exercise capacity after adjustment for age and HF etiology.

CONCLUSIONS

The ability to restore diastolic synchronicity at exercise predicts exercise capacity in patients with HFREF.