A new predictor of atrial fibrillation after coronary artery bypass graft surgery: HATCH score
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* Mithat Selvi
* Hasan Gungor
* Cemil Zencir
* Sevil Gulasti
* Ufuk Eryilmaz
* Cagdas Akgullu
* Selim Durmaz

## Abstract

The aim of this study was to investigate the association between HATCH score and atrial fibrillation (AF) after coronary artery bypass graft (CABG) surgery. 369 patients (103 patients with AF and 266 patients without AF) undergoing isolated CABG surgery were analyzed. Complete medical records were retrospectively collected to investigate HATCH score. The median age of patients with AF was significantly higher than the median age of non-AF group (60.8±10.0 years vs 67.8±9.5 years, P<0.001). HATCH score was significantly higher in patients who developed AF after CABG surgery than the non-AF group (P=0.017). Multivariate logistic regression analysis showed that HATCH score (OR 1.334; 95% CI 1.022 to 1.741, P=0.034) was an independent predictor of AF after CABG surgery. Receiver operating characteristic curve analysis showed that the cut-off point of HATCH score related to predict AF was >1 (two or more), with a sensitivity of 42% and specificity of 70%. Patients with elevated preoperative HATCH score may have higher risk for AF after CABG surgery.

*   atrial fibrillation
*   coronary artery bypass

### Significance of this study

#### What is already known about this subject?

*   The most widespread arrhythmia after cardiac surgery is postoperative atrial fibrillation (POAF).

*   HATCH scoring system was composed as calculating individual points based on the presence of hypertension, age >75 years, transient ischemic attack (TIA) or stroke, chronic obstructive pulmonary disease and heart failure.

*   In recent studies, higher HATCH score was found to be correlated with the progression of atrial fibrillation (AF).

#### What are the new findings?

*   HATCH score was significantly higher in patients who developed AF after coronary artery bypass graft (CABG) surgery than the non-AF group (P=0.017).

*   Multivariate logistic analysis showed that HATCH score (OR 1.334; 95% CI 1.022 to 1.741, P=0.034) was an independent predictor of AF after CABG surgery.

*   Our receiver operating characteristic analysis showed that the cut-off point of HATCH score related to predict AF was >1 (2 or more), with a sensitivity of 42% and specificity of 70%.

#### How might these results change the focus of research or clinical practice?

*   Patients with elevated preoperative HATCH score may have higher risk for AF after CABG surgery.

*   Prospective and multicenter studies with long-term follow-up are needed to support our findings.

## Introduction

Atrial fibrillation (AF) is the most widespread arrhythmia after cardiac surgery. Recent studies have shown that the incidence of AF after coronary artery bypass graft (CABG) is about 25%–40% among postoperative patients.1–3 Postoperative atrial fibrillation (POAF) is associated with an increased incidence of heart failure, cerebrovascular diseases, mortality, prolonged hospitalization, renal insufficiency and raised social costs.1–4

Prophylactic therapy with antiarrhythmic drugs can be preferred to decrease the incidence of POAF.5 6 This option is not cost-effective because of the side effects of the drugs, and also prophylactic therapy for all patients who undergo CABG is not considerable. Therefore, an acceptable risk assessment tool for POAF is needed.

Progression of AF is associated with the underlying structural heart diseases and electroanatomical remodeling of the left atrium.7 In recent studies, higher hypertension, age ≥75 years, transient ischemic attack or stroke, chronic obstructive pulmonary disease, and heart failure (HATCH) score was found to be correlated with the progression of AF.8 9 Each component has a value of one point apart from stroke and heart failure, which have values of two points each. The aim of our work was to assess the association between HATCH score and POAF.

## Materials and methods

### Study designs

The present study was retrospective and single center.

### Patients and eligibility criteria

In our work, patients who had isolated CABG surgery as elective at the department of cardiovascular surgery in Adnan Menderes University Hospital between January 2011 and December 2015 were analyzed retrospectively. Patients with infections, autoimmune and proinflammatory diseases, malignancy, arthritis, the use of digitalis, steroids, amiodarone and propylthiouracil before CABG surgery, preoperative AF or any other arrhythmia, previous diagnosis of paroxysmal AF, hyperthyroidism, the presence of a permanent pacemaker or an implantable cardioverter defibrillator, the diagnosis of decompensated congestive heart failure, a hemodynamically unstable condition before CABG surgery, myocardial infarction for less than 7 days, the need for urgent surgery, the presence of chronic renal failure (creatinine >2 mg/dL), and patients undergoing a second bypass surgery and concomitant valvular surgery were excluded. In all, 369 consecutive patients who had been providing inclusion criteria were admitted to the study. HATCH score of the patients who had enrolled in the study were estimated and patients were separated into groups according to these scorings. Furthermore, details of preoperative treatment, baseline clinical characteristics, angiographic results, echocardiographic features, and intraoperative and postoperative detections were recorded.

### HATCH score

The HATCH scoring system depends on a point system in that one point is given for hypertension, COPD, age (75 years or more) and two points each are given for heart failure (ejection fraction<40%) and stroke or TIA. All eligible patients were classified according to preoperative HATCH scores.

### POAF definition

After cardiac surgery, all the patients were admitted to intensive care unit. A heart rhythm monitor recorded the changes of the ECG. A 12-lead ECG was used for documentation of the arrhythmic events on the patients. POAF was defined as documentation during ECG at least 30 s of AF.

### Echocardiography

An echocardiogram (Vivid 5 s, GE Vingmed Ultrasound A/S, Horten, Norway) with a 3.5-MHz transducer was carried out in all patients, and the subsequent data were enrolled: left ventricular end-systolic diameter, left ventricular end-diastolic diameter, left ventricular ejection fraction (LVEF), degree of valvular dysfunction and left atrial diameter. The Simpson method was used to estimate LVEF.

### Statistical analysis

Whole statistical analyses were performed using SPSS V.15.0 for Windows software. Continuous variables were examined for normal dispersion by the Kolmogorov-Smirnov test. We described continuous variable data as mean and SD or median and min–max. We compared continuous variables using the Student’s t-test or Mann-Whitney U test between groups. Categorical variables were briefed as percentages and cross-checked with the χ2 test. The predictive values of HATCH score were evaluated using receiver operating characteristics (ROC) curve analysis. The threshold of value for HATCH score was estimated about predicting POAF. Statistical significance was considered according to a P value <0.05 for whole analyses.

## Results

Of the 369 study patients, 103 (28%) developed POAF. Median time for POAF existence was 2.6 days (range 1–9) and mean termination time for POAF was 20.2 hours (range 1–123).

The preoperative drugs, baseline characteristics, echocardiographic and laboratory findings with POAF (AF group) and without POAF (non-AF group) are shown in tables 1 and 2. The median age of AF group was significantly higher than the median age of non-AF group (60.8±10.0 years vs 67.8±9.5 years, P<0.001). Only advanced age obtained the statistical significance in cardiovascular comorbidities between two groups.

View this table:
[Table 1](/content/early/2017/11/04/jim-2017-000525/T1)

Table 1 
Baseline characteristics and preoperative medications

View this table:
[Table 2](/content/early/2017/11/04/jim-2017-000525/T2)

Table 2 
Laboratory and echocardiographic parameters of patients

In patients who developed POAF, the median of HATCH score was detected as 1.5 (0–6). However, the median of HATCH score for non-AF group was detected as 1.2 (0–6). HATCH score was significantly higher in patients who developed AF after CABG surgery than the non-AF group (P=0.017). Multivariate logistic analysis showed that HATCH score (OR 1.334; 95% CI 1.022 to 1.741, P=0.034) was an independent predictor of AF after CABG surgery (table 3). ROC curve analysis showed that the cut-off point of HATCH score related to predict AF was >1 (two or more), with a sensitivity of 42% and specificity of 70% (figure 1). In addition, the distribution of AF among the HATCH scores was shown as the bar chart (figure 2).

View this table:
[Table 3](/content/early/2017/11/04/jim-2017-000525/T3)

Table 3 
Multivariate logistic regression analysis

![Figure 1](/https://d3hme472k3gd2d.cloudfront.net/content/jim/early/2017/11/04/jim-2017-000525/F1.medium.gif)

[Figure 1](/content/early/2017/11/04/jim-2017-000525/F1)

Figure 1 
Receiver operating characteristics curve of HATCH score for predicting atrial fibrillation after coronary artery bypass graft surgery. AUC, area under the curve; HATCH, hypertension, age ≥75 years, transient ischemic attack or stroke, chronic obstructive pulmonary disease, and heart failure.

![Figure 2](/https://d3hme472k3gd2d.cloudfront.net/content/jim/early/2017/11/04/jim-2017-000525/F2.medium.gif)

[Figure 2](/content/early/2017/11/04/jim-2017-000525/F2)

Figure 2 
The distribution of atrial fibrillation among the hypertension, age ≥75 years, transient ischemic attack or stroke, chronic obstructive pulmonary disease, and heart failure (HATCH) scores.

The risk factors for AF are as follows: age >75 years, female gender, having heart failure, LVEF<40%, CHA2DS2-VASC score2 or more, having hypertension, peripheral artery disease, diabetes, COPD, and LA diameter >4 cm. CHA2DS2-VASC scoring system which contains congestive heart failure, hypertension, age>75, stroke, female gender and vascular diseases is the current scala for predicting thromboembolic events in AF patients. Three hundred and twenty patients had at least one of these risk factors, and 49 did not have any risk factor. Among those who have at least one risk factor, 96 (30%) of them had AF, whereas only 7 (14%) of those who do not have any risk factor had AF (P=0.02).

## Discussion

AF is the most widespread arrhythmia after cardiac surgery. Recent studies have shown that the incidence of AF after CABG is about 25%–40% among postoperative patients.1–3 The mortality raises because of thromboembolic complications in patients with POAF. In addition, hospital costs increases due to prolonged hospitalization. In several studies, POAF has been associated with twofold to fourfold raised risk of cerebrovascular disease, a 4-day to 5-day raise in hospital length of stay, and a rise in the expense of care of about US$10 000 per patient.10–15 Hence, predicting POAF is crucial to decrease healthcare complications and hospital costs.

Several risk factors were defined to predict POAF in previous studies. Age, gender, previous AF history, hypertension, COPD, heart failure, prior myocardial infarction, heart rate, smoking, body mass index, left atrial diameter, valvular heart disease, postoperative bleeding, postoperative hypokalemia and chronic kidney disease were reported as risk factors for POAF.1–3 In recent literature, PR-interval and QRS duration were found as useful for predicting POAF.16 According to the ALDO-POAF study, preoperative plasma aldosterone and galectin-3 levels could be helpful for prevention of POAF.17 Also, Gungor *et al* demonstrated that progression of AF after CABG surgery can be predicted by preoperative poor coronary circulation and POAF may be encountered more frequent in patients with increased postoperative resistin level.18 19 However, there has been no consensus about predicting POAF for preoperative state.

Hypertension, age, TIA, COPD and heart failure are used to assess the development of persistent AF. These independent predictors were originated by Cees B de Vos and it was named as the HATCH score.8 According to this study, higher HATCH score causes progression of AF and rhythm or rate control strategy might be determined. Furthermore, the HATCH score was evaluated in patients with typical atrial flutter for predicting the repetition of AF by Chen *et al*.20 They have demonstrated that left atrial diameter and the HATCH score are significant predictors for new onset AF. Correlation between left atrial diameter and the HATCH score might be an outcome of atrial remodeling which has been caused by underlying structural heart diseases. Thus, the HATCH scoring system is related with altered electroanatomical characteristics of left atrium which have comprised some cellular pathological mechanisms of atrium as fibrosis and cellular hypertrophy. Several studies documented that with higher HATCH scores, AF recurrences after catheter ablation more frequent.9 21 22 Tischer *et al* showed that prevalence of AF increases with higher HATCH scores.23

In our work, we intended to research the association between HATCH score and POAF. In literature, there have been very limited data about this subject. As a first paper, Emren and co-authors analyzed HATCH score in 284 consecutive patients who underwent CABG surgery. They have documented that the HATCH score can be used for predicting POAF.24 According to their ROC analysis, if the HATCH score was 2 or more as a threshold, there were 72% sensitivity and 75% specificity for POAF. Furthermore, advanced age, COPD, left atrial enlargement (>35 mm), lower ejection fraction (<40%) were statistically significant about development of POAF in their study. Our study design was similar to their study but there have been some differences between two works. Firstly, our study population was larger than their study. Secondly, our ROC analysis showed that the cut-off point of HATCH score related to predict AF was >1 (two or more), with a sensitivity of 42% and specificity of 70%. In addition, only advanced age obtained the statistical significance about development of POAF in our study. In this topic, we have the second paper and we found that the HATCH score can predict AF after CABG. The HATCH score is a simple, inexpensive and non-invasive tool for utilization. Antiarrhythmic treatment can be easily initiated according to this scoring system at preoperative state.

## Limitations

The POAF after discharge of intensive coronary unit was diagnosed according to the symptoms of patients or daily ECG records. In this period, some of short or asymptomatic AF episodes have been missed and they have been included in the other group due to lack of continuous ECG monitoring. The other significant limitation of the present study was retrospective study design. In addition, our study reports a single-center experience. Prospective and multicenter studies with long-term follow-up are needed to support our findings.

## Conclusion

Patients with elevated preoperative HATCH score may have higher risk for AF after CABG surgery. Antiarrhythmic therapy can be considered according to this scoring system at preoperative state.

## Footnotes

*   Contributors MS was responsible for the data collection, writing and is the corresponding author. HG was responsible for the data collection and writing of the article. CZ was involved in the reviewing and forming the tables. SG did the statistical analysis. UE and CA reviewed the article. SD gave additional opinion to the original idea.

*   Competing interests None declared.

*   Provenance and peer review Not commissioned; externally peer reviewed.

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    [Abstract/FREE Full Text](/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NjoiY2lyY2FlIjtzOjU6InJlc2lkIjtzOjc6IjYvNC83NTQiO3M6NDoiYXRvbSI7czo0MjoiL2ppbS9lYXJseS8yMDE3LzExLzA0L2ppbS0yMDE3LTAwMDUyNS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

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