Impact of cardiac resynchronisation therapy in patients with cardiac sarcoidosis

Background

Implantation of a device is usually required in cardiac sarcoidosis (CS) patients presenting with advanced conduction abnormalities or ventricular arrhythmias. A cardiac resynchronisation therapy (CRT) device is often chosen in patients with concomitant left ventricular systolic impairment. The role of CRT in CS is not well established.

Purpose

To describe the cohort of CS patients with CRT device in situ in our hospital focusing on the short-term effect in serial echocardiography and long-term outcomes on morbidity and mortality.

Methods

All consecutive CS patients with a CRT device in situ were identified in our CS database (2005–2022). A confident CS diagnosis was provided after review of all relevant clinical and imaging baseline data in our CS multi-disciplinary meeting and a consensus decision for CRT-D implantation was made based on international guidelines. All patients were followed up for at least 6 months with serial echocardiography. Serial data regarding symptoms, rhythm disturbance and echocardiographic parameters were obtained and comparisons were performed using Wilcoxon signed rank test.

Results

A total of 51 CS patients with CRT-D were identified (mean age: 57±10 years old). Patients were male predominant (64.7%) and Caucasian in origin (86.2%). Extra-cardiac sarcoidosis was confirmed histologically in 33 (64.7%) patients. The prevalence of smoking, diabetes, hypertension and ischaemic heart disease was 27.5%, 21.6%, 49.0% and 7.8% respectively. At the time of device implantation or during follow-up, 43 (84.3%) patients were found to have active cardiac sarcoidosis on cardiac PET.

Post CRT implantation there was a significant difference in LV ejection fraction (35.9±15.0% vs 42.2±14.1%, p<0.001), LV end-systolic diameter (4.90±1.46 cm vs 4.62±1.32 cm, p=0.012) and LV end-diastolic diameter (5.99±1.18 cm vs 5.66±1.06 cm, p<0.001). No significant changes were observed in the right ventricular function (p=0.09) and severity of mitral regurgitation (p=0.40). There was one patient who experienced acute heart failure decompensation admission within six months of CRT-D implantation. The New York Heart Association (NYHA) class improved in 26 patients (51.0%), worsened in 4 (7.8%) patients and remained the same in 21 (41.2%) patients at 6 months post CRT-implantation. During the mean follow up of 47.6 months, the composite end-point of death and cardiac transplantation was reached in 9 (17.6%) patients (8 deaths and 1 cardiac transplantation). 5 patients had major complications including a large haematoma, a small atrio-septal defect, haemothorax, device associated endocarditis and lead fracture. Minor wound infections were seen in 3 patients and 4 patients received inappropriate shock or anti-tachycardia pacing.

Conclusions

CRT in cardiac sarcoidosis patients is associated with short-term improvement in LV remodelling and functional status but over a four year follow up, morbidity and mortality are common.

Funding Acknowledgement

Type of funding sources: None.

Blood ketone measurement as a test for dietary compliance in cardiac sarcoid patients undergoing 18f-fluorodeoxyglucose positron emission tomography

Funding Acknowledgements

Type of funding sources: None.

Background

Imaging with 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) is used as part of diagnosis and monitoring response to therapy in patients with cardiac sarcoidosis. In order to supress myocardial uptake of 18F-FDG patients prepare with a low carbohydrate diet followed by an 18-hour overnight fast. Failure to comply with the protocol results in diffuse myocardial 18F-FDG uptake which confounds diagnostic interpretation.

Purpose

To assess if point of care blood ketones could be used as a marker of dietary compliance and association with suppression of myocardial 18F-FDG uptake on PET scan.

Method

Patients (n = 26, 57 ± 4 years, 65% Male) from a single centre were instructed to follow standard preparation protocol prior to 18F-FDG PET/CT. After confirmation of dietary compliance, blood glucose and blood ketones were recorded using point of care devices. Images were graded based on the pattern of myocardial 18F-FDG uptake.

Results

There was no clear correlation between blood ketones in relation to dietary compliance or myocardial 18F-fluorodeoxyglucose uptake. In those with myocardial 18F-FDG uptake maximum standardized uptake value (SUV max) within the myocardium ranged from 2.3 to 9.8 (Mean 5.3) and ketone from 0.1 – 0.7 (normal <0.6).

Non-diabetic patients and those on steroids achieved adequate fasting glucose without significant rise in blood ketones. 60% of diabetic patients demonstrated mildly elevated ketones between 0.6-1.5mmol/L.

Conclusion

Current protocol with low carbohydrate diet and 18-hour fast achieves adequate quality of images in majority of patients, without significant change in blood ketones. Therefore, blood ketones cannot be used to confirm dietary compliance.  Diabetic patients on insulin may benefit from ketone measurement due to risk of diabetic ketoacidosis.

Cardiac sarcoidosis with complete metabolic response and resolution of left ventricular dysfunction complicated by subsequent VT storm

Sarcoidosis is a multisystem granulomatous disease of unknown aetiology that involves primarily the lungs and lymph nodes. Cardiac involvement is less common but associated with a poorer prognosis. With contemporary diagnostic modalities such as cardiac magnetic resonance and fluorine-18-fluoro-deoxy-glucose positron emission tomography computed tomography, cardiac involvement in sarcoidosis is increasingly diagnosed with appropriate therapy improving outcomes. Although steroid therapy may be protective or therapeutic in preventing left ventricular scarring and preserving LV function, it may not be as effective in the late stages of disease. (Chiu et al in Am J Cardiol 95:143-146, 2005) We present a case of cardiac sarcoidosis with significantly impaired ejection fraction that was diagnosed late in the course of disease with complete metabolic response to therapy and an improvement of LV function, but with a subsequent complication of ventricular tachycardia storm.

Advances in radionuclide imaging of cardiac sarcoidosis

INTRODUCTION

Radionuclide imaging for the diagnosis and monitoring of cardiac involvement in sarcoidosis has advanced significantly in recent years.

SOURCES OF DATA

This article is based on published clinical guidelines, literature review and our collective clinical experience.

AREAS OF AGREEMENT

Gallium-67 scintigraphy is among the diagnostic criteria for cardiac involvement in systemic sarcoidosis, and it is strongly associated with response to treatment. However, fluorine-18, 2-fluoro-deoxyglucose (FDG) positron emission tomography (PET) is now preferred both for diagnosis and for assessing prognosis.

AREAS OF CONTROVERSY

Most data are from small observational studies that are potentially biased.

GROWING POINTS

Quantitative imaging to assess changes in disease activity in response to treatment may lead to FDG-PET having an important routine role in managing cardiac sarcoidosis.

AREAS TIMELY FOR DEVELOPING RESEARCH

Larger prospective studies are required, particularly to assess the effectiveness of radionuclide imaging in improving clinical management and outcome.

PET/CT in oncology—a major advance

The concept of hardware fusion between positron emission tomography (PET) and computed tomography (CT) has only been introduced commercially in the last 4 years. The advantages of this combined technique over PET alone have become obvious. There is increasing evidence to suggest that PET/CT adds complementary information in staging, re-staging and follow-up in oncology patients, leading to changes in management plans. The present paper is a review of the strengths, weaknesses, current evidence and future directions of this technique.