Transit time flow measurement (TTFM) as a predictor of graft failure and major adverse cardiac events following coronary artery bypass grafting (CABG)

Funding Acknowledgements

Type of funding sources: None.

Introduction

Post coronary artery bypass grafting (CABG), coronary angiography (CAG) is the gold standard for graft assessment to check the presence of occlusion or stenosis. Despite this, CAGs after a CABG in the nation are only conducted if patients show ischemic signs. Alternative to CAG, transit time flow measurement (TTFM) can be utilized to determine overall quality of blood flow in grafts. TTFM has yet been utilized to assess graft patency despite its availability in the nation.

Purpose

This study aims to provide TTFM profiles from CABG surgeries, including characterizing the differences in TTFM parameters between failed and normal grafts, as well as determining the association of TTFM parameters and related clinical factors to the likelihood of graft failure and major adverse cardiac events (MACE).

Methods

279 patients were admitted to the cardiology centre from 1 January 2017 to 31 December 2019. Mann-Whitney test was used to compare the differences in TTFM parameters across different graft types, as well as between failed and normal grafts. To determine the likelihood of a graft being normal or failed based on established TTFM parameter cutoffs, χ² test was used. Lastly, multivariate logistic regression was used to determine the association between TTFM parameters and MACE, specifically angina, myocardial infarction, and death.

Results

Different graft types exhibited significant differences in TTFM parameters, particularly pulsatility index (PI) and diastolic filling (%DF). Arterial grafts presented with higher quality of blood flow compared to venous grafts, with left-sided grafts (especially LIMA-LAD) being the graft type of highest quality (Refer to Fig.1).

However, there were no differences in TTFM parameters between failed and normal grafts (PI P = 0.893; DF% P = 0.143). Despite this, there was a greater number of failed grafts with PI > 5 (6.6%) compared to PI < 5 (2.6%) (χ²=4.021, P = 0.045).

Multivariate analysis showed no significant association between TTFM parameters and prevalence of MACE. Instead, an increased risk of graft failure is associated with the female gender (P = 0.031), history of congestive heart failure (P = 0.025) and poor renal function (P = 0.034). Also, an increased risk of MACE is associated with a history of coronary intervention (P = 0.041), left coronary dominance (P = 0.018) and renal function (P = 0.009).

Conclusion

This study provides an overview of the TTFM profiles among different graft types used in CABG surgeries. While TTFM are not indicative of failed grafts upon ischemic signs, patient comorbidities were informative. Follow-up studies should include a larger sample size of patients from an earlier timeframe to assess correlation of graft failure over a 5-to-10-year span post-CABG. Regardless of ischemic signs, routine CAG for all patients should be considered to determine the true prevalence of graft failure among CABG patients in the nation. Abstract Figure. Fig1.Median comparison TTFM Parameters  Abstract Figure. Fig2. Multivariate analysis models

Outcomes of cardiac CT investigations in patients from the Rapid Access Chest Pain clinic with consideration to additional CT modalities and individual risk factors

Funding Acknowledgements

Type of funding sources: None.

Coronary CT is a first line investigation according to NICE guidelines, yet there are still uncertainties in its ability to decrease adverse event rates. The high sensitivity and high negative predictive value of coronary CT only validates low to moderate pre-test probability of attaining significant CAD due to its low positive predictive value. Improving outcomes in coronary CT could avoid events and limit the use of invasive modalities such as invasive coronary angiography. Increased probability of MACE with presence of risk factors could also raise the merit of risk stratification utilization for better classification.

This study provides insight into the effectiveness of CT as a first-line investigation for new onset angina referred to RACPC regardless of CAD probability and any further testing. Data differences on outcome probabilities in risk stratification utilization and different CT modalities, both coronary calcium scoring and coronary angiography, raised notion that the incremental value of these tools should not be overlooked. End-outcomes would compromise of MACE composites after a 6-month follow-up. We hypothesize that patients investigated with coronary CT as opposed to without, with presence or absence of functional testing, would grant better clinical outcomes.

Data on 155 patients who registered in RACPC were identified and collected from Brunei Health Information Management Systems for a one-year period (August 2018- August 2019). Information on sociodemographic, risk factors, further diagnostic testing, CT reports and event follow-up at 6 months were extracted, subject to availability. Probability of CAD in patients were classified according to CCS and CTCA results.

CAD was detected in 62 (40.0%) patients with non-obstructive or obstructive CAD in addition to low to high calcium scores. Over the 6-month follow-up period, MACE occurred in 8 patients in the CT group (6.3%) and 4 (13.8%) without CT. 126 (81.3%) patients with CT did not attain MACE (p = 0.19) and chances of getting CABG after adjustments with co- founding factors were significantly lower than without CT [HR = 2.654e-06; 95% CI = 2.204e-07-3.195e-05; p= <0.001]. A higher event probability was associated with a high CCS (41.1%) (p= <0.001) than abnormal CTCA (11.4%) (p = 0.018). MACE was also associated with multiple risk factors such as age (p= <0.001), hypertension (p = 0.001), diabetes (p= <0.001), high cholesterol(p = 0.027), and abnormal total cholesterol (0.010) and creatinine levels [serum creatinine, p= 0.017; creatinine clearance, p = 0.006].

Outcomes measured were not significantly better in those with cardiac CT however risk of coronary artery bypass graft was significantly lower. CCS is better than CTCA in event prospects but both possess promising prognostic values in healthy arteries. Multiple CAD risk factors associated with MACE were likely as a result of intense atherosclerosis, marking appeal for risk stratifications and preventive measures. Abstract Figure. Kaplan-Meier curves for MACE  Abstract Figure. Multiple cox regression models

ECG changes in psychiatric patients on psychotropic medications

Funding Acknowledgements

Type of funding sources: None.

Background

Suicide and euthanasia accounts for 14.3% of deaths in those with psychiatric conditions. The rest are attributed to preventable causes such as cardiovascular disease, respiratory disease, and infections. Several psychotropic medications have been associated with sudden death due to their effect on prolonging QT interval, resulting in the development of a polymorphic ventricular arrhythmia, Torsades de Pointes (TdP). TdP may be self-limiting or lead to sudden cardiac arrest and death.

Purpose

This study aims to evaluate the cardiotoxic effects of psychotropic medications.

Method

This is a descriptive retrospective study of patients submitted to the local psychiatric wards within one year. Patients with psychotropic drug prescriptions were included while patients below 18 years old, pregnant, or did not have ECG performed were excluded. The control group consisted of sex- and age- matched patients with ECG conducted for occupational health purposes. Multiple regression models were conducted to investigate the predictors of significant ECG differences.

Result

Of the 154 psychiatric inpatients admitted, exclusions were 44 patients due to exclusion criteria and 19 patients due to difficulty in physical file access. The study population (n = 91) had a mean age of 36.7 years old with 40.7% female and 59.3% male. The predominant diagnoses were schizophrenia and delusional disorders (58.2%). 86 psychiatric patients (94.5%) were prescribed antipsychotic drugs (APD).

A significantly higher proportion of psychiatric patients has a history of smoking (p < 0.001), alcohol consumption (p = 0.001), and illicit drug use (p < 0.001). They also exhibited significantly more co-morbid illnesses including hypertension (p = 0.022), hyperlipidaemia (p = 0.013), diabetes (p = 0.026) and thyroid disease (p = 0.023) than the control population.

Psychiatric patients had a significantly higher mean heart rate (79.9 vs 69.6 ms; p < 0.001) and QTc interval (452.2 vs 418.6ms; p < 0.001). Mean QTc interval was significantly longer for psychiatric patients in both male (454.2 vs 414.5ms; p < 0.001) and female (449.3 vs 425.6 ms; p = 0.029) gender. Psychotropic drug use is a significant predictor for both prolonged heart rate (p < 0.001) and prolonged QTc interval (p < 0.001). Electrolyte imbalance is a significant predictor of prolonged QTc interval only (p = 0.036). One year follow of both groups detected only 1 psychiatric patient with palpitation.

Conclusion

Psychiatric patients on psychotropic medications have a longer baseline heart rate and QTc interval, which was not associated with MACE at 1 year. None of the underlying comorbidities and lifestyle choices were significant predictors of this. Electrolyte abnormalities and psychotropic drug use significantly predicted QTc prolongation. However, these findings were largely driven by APD use. A follow-up study of a longer period is recommended to investigate whether patients with prolonged QTc interval are of higher risk of MACE occurrence.