Background of the Study

Ischemic heart disease (IHD) is a leading cause of death worldwide. Also referred to as coronary artery disease (CAD) and atherosclerotic cardiovascular disease, it manifests clinically as myocardial infarction and ischemic cardiomyopathy.¹

 

The incidence and mortality rates related to IHD are falling in most developed and developing countries. Absolute numbers are still rising, thus IHD has become a worldwide public problem.²

 

Globally, 17.9 million people succumbed to CAD, accounting for 31% of deaths worldwide. More than 75% of these deaths occur in low- and middle-income countries.³ Moreover, by 2025, 80%–90% of people in low- and middle-income countries are projected to die from CAD, making it one of the leading causes of death worldwide.⁴

 

In Manila, despite the deadly coronavirus disease 2019 (Covid-19) battering the country, coronary heart disease remains the top cause of death in the Philippines from January to November last year, according to the Philippine Statistics Authority (PSA).⁵ Among the male population, approximately 62,200 people have died from the disease. Meanwhile, just over 43,100 female population in the country succumbed to death due to ischemic heart disease (IHD).⁶ At present, both international and local guidelines recommend revascularization by coronary artery bypass graft (CABG) surgery when indicated for the improvement of survival of high-risk patients. According to guidelines of the American Heart Association of 2021, the class 1 indication of CABG for those patients with mild angina is significant left main coronary artery stenosis with ≥70% stenosis of proximal left anterior descending and proximal left circumflex artery and involvement of 3-vessel disease with survival benefit greater in patients with abnormal left ventricular function and ejection fraction of <50%.⁷

 

In the Philippines, CABG is costly, considering that majority of patients with IHD belong to low- and middle-income groups. In the study done by Galicio, et al., in 2010, the annual statistics of patients undergoing CABG surgery is 500 to 600 and the Philippine Heart Center statistics has a comparable mortality rate with foreign data, 3.69% versus 2.5%, respectively.⁸

 

In 2013, the Philippine Health Insurance Corporation developed the ‘Z benefit’ package (ZBen) to give assistance to patients who cannot afford to undergo the following cardiac procedures: CABG, total correction of Tetralogy of Fallot (TOF) and closure of ventricular septal defect (VSD).⁹

In 2021, Dela Cruz, et al., published a paper on the clinical profile of patients who underwent CABG availing of the Philhealth ZBen package at the Philippine General Hospital (PGH) from March 2017 to December 2018. Out of 63 patients screened, 62 patients were approved by the screening panel to undergo CABG. Demographic profile showed mean age of 60 ± 8, hypertensive males with three-vessel involvement in coronary angiogram. Objectives included timelines from identification of the need for CABG to eligibility screening for approval, Philhealth approval and performance of surgery. Result showed the following timelines: screening approval had a median of 25 days (interquartile range (IQR) 12 - 63), Philhealth approval had a median of 45 days (IQR 26 - 95) and timing of surgery had a median of 58 days (IQR 29 - 118).¹⁰

Manila Doctors Hospital (MDH) has provided CABG services since 2009, acquiring 40-50 procedures per year. Availment of the ZBen package at MDH started in 2013. In an unpublished case series done by Dr. Dimalala, et.al., involving 37 patients under the ZBen package from July 2017 to July 2018, the demographic profile showed predominance of male patients with hypertension and three-vessel disease on coronary angiogram. No mortality was reported and there was a 22% morbidity rate due mostly to hospital-acquired pneumonia.¹¹

Significance of the Study:

This study aims to get a profile on the population of those who avail of this benefit and adequacy of such a benefit on in-hospital outcomes.

Definition of Terms

Syntax score

The Syntax score is an angiographic tool to help cardiologists, interventionists and surgeons grade the complexity of coronary artery lesions. A higher Syntax score indicates a more complex condition as well as worse prognosis in patients undergoing contemporary revascularization, especially with percutaneous coronary intervention (PCI).¹²

Acute kidney injury

Increase in sCr ≥0.3 mg/dL (≥26.5 umol/L) within 48 hours; or increase in sCr ≥1.5 times baseline, which is known or presumed to have occurred within the prior seven days; or urine volume <0.5 mL/kg/h for six hours.¹³

Cardiovascular death

Cardiovascular death endpoint, often used to assess cardiovascular safety, includes a composite of cardiovascular death, non-fatal myocardial infarction and non-fatal stroke.¹⁴

Non-cardiovascular death

Non-cardiovascular mortality was defined as all other causes of death, infection, refusal of treatment, withdrawal, cachexia and malignancies.¹⁴

STS risk score

The STS risk score is designed to predict adverse outcomes in patients undergoing CABG, including the risk of death, renal failure, permanent stroke, prolonged ventilation, deep sternal wound infection, re-operation and prolonged length of stay.¹⁵

Bleeding

According to the Bleeding Academic Research Consortium (BARC) type 4, CABG-related bleeding is defined as bleeding resulting in death, or re-operation due to bleeding, or intracranial hemorrhage, or transfusion of 5 or more units of RBCs over 48 h, or chest tube drainage in excess of 2000 mL over 24 hours.¹⁶

Class I Indication

Evidence and/or general agreement that a given treatment or procedure is beneficial, useful and effective.¹⁷

Clinical Research Question:

Among patients who underwent CABG under Philhealth Z-Benefit package from July 2017 to October 2023 at Manila Doctors Hospital, what are the clinical profiles and in-hospital outcomes?

General Objective

 

To determine the clinical profile and in-hospital outcomes among patients who underwent CABG under the Philippine Health Insurance Corporation (Philhealth) Z Benefit Package (PZBP) from year July 2017 to October 2023 at Manila Doctors Hospital.

Specific Objectives

 

1. To determine the clinical profile of patients who underwent CAG under Z-Benefit at MDH from July 2017 to October 2023 in terms of;
   1. Demographic
      1. Age
      2. Gender
      3. BMI
      4. Smoking history
      5. Occupation
   2. Comorbidities
      1. Hypertension
      2. Diabetes mellitus (DM)
      3. Renal disease
      4. Cerebrovascular disease
      5. Dyslipidemia
      6. Obesity
      7. Previous myocardial infarction (MI)
      8. Previous PCI
      9. Lipid profile
      10. Fasting blood glucose (FBS)
      11. HbA1_c
   3. Provincial regions
   4. Echocardiographic findings: Ejection fraction
   5. Angiographic findings
      1. Number of vessels occluded
      2. Left main involvement
   6. Baseline clinical risk scores
      1. Syntax I
      2. Syntax II
      3. Euro score II
      4. STS score
2. To determine the incidence of in-hospital outcomes observed among patients who underwent CABG under Z-Benefit in terms of:
   1. Mortality
      1. All cause
      2. Non-cardiovascular
      3. Cardiovascular death
   2. Stroke
   3. Pneumonia
   4. Acute Kidney Injury
   5. Arrhythmia
      1. Ventricular tachycardia
      2. Atrial fibrillation
      3. Supraventricular tachycardia
   6. BARC Type IV bleeding
   7. Post CABG MI
3. To determine the length of hospital stay among patients who underwent CABG under Z-Benefit.

 

Methodology

Research Design: This is a retrospective descriptive cohort study.

 

Study population: Adult patients who underwent CABG under PZBP from July 2017 to October 2023 in Manila Doctors Hospital.

Inclusion Criteria:

1. All adult patients ≥19 years of age and above.
2. All patients who underwent CABG under the ZBen package at MDH.

 

Exclusion Criteria:

1. Data on patients who underwent CABG under the ZBen package that cannot be retrieved.

 

Study Framework: In Manila Doctor’s Hospital equipped and capable of CABG procedure.

Study Duration: July 2017 to October 2023

Sampling Method: Purposive type of sampling

Data Collection and Data Encoding Plan

Patients were identified from the ZBen census from July 2017 to October 2023. The data collection was complemented by accessing the hospital’s record section for clinical profile and outcomes of these patients. Demographics, clinical and laboratory data, as well as imaging studies were collected. Clinical outcomes were also determined. All data were collected by a trained research assistant (RA).

A standardized data collection form (DCF) (Appendix A) with no individual patient identifier was used to document the variables. A data encoder received the DCF and entered all variables in the database. Both the RA and data encoder were asked to provide periodic descriptive analysis based on the encoded DCFs and coordinated with the authors and statistician for needed analysis.

Statistical Analysis

Data encoding and analysis were performed using Excel^TM 2016. Statistical analysis was performed in STATA SE version 13. Qualitative data were tabulated and presented as frequency and percent distribution. Quantitative variables were summarized as mean and standard deviation.

Budget: The budget for the research assistant and data encoder were provided by MDH Cardiovascular Center under the Medical Directorate.

Ethical Considerations:

All the authors, RA and data encoder have undergone Good Clinical Practice (GCP) research workshop and received GCP certification. The protocol was carried out according to the Principles of the Declaration of Helsinki. The protocol was submitted for review and approved by the Committee on Research (CORES) and Research Ethics Board (IRB) of MDH. There was no conflict of interest between the investigators and the proposed study. Benefits to the patients were indirect since added knowledge would assist the institution on its provision of better service and quality of care.

Data Privacy Section

All information gathered for this study was anonymized in compliance with the Data Privacy Act of 2017. Only data needed to answer the objectives of this paper were collected. Data processing was in a password protected computer and kept confidential in a dedicated laptop owned by the Flagship Outcome Research Core group. All raw data were kept protected up to five years and will then be destroyed.

Results

 

In the data collected from July 2017 to October 2023, a total of 126 patients were included in this study. Table 1 represents the baseline clinico-demographic characteristics of patients diagnosed with CAD who fulfilled the eligibility screening. The mean age of the population was 60 years. There were notably more males (87%) compared to females (12%). The mean body mass index (BMI) was noted to be 25 kg/m². The most common comorbidities reported were hypertension (89%), obesity (60%) and diabetes mellitus (52%), while there were only two patients (1.6%) with no known comorbidities. There were 82 patients who were chronic smokers and 71 were with dyslipidemia patients were unemployed (56%). Moreover, several patients also had previous MI and percutaneous angioplasty comprising of 47 and 22 patients, respectively. Among diabetic patients, only 39 patients had HbA1_c and 120 patients had FBS. Almost all patients were diagnosed with dyslipidemia but only 37 patients had complete lipid profile in chart review.

 

Table 1. Clinical profile of patients of who underwent coronary artery bypass grafting in Manila Doctors Hospital under the Philhealth ZBen package from July 2017 to October 2023

 

Total (n = 126)
Mean Age in Years (± SD)	60.18 ± 8.96
Sex: Male Female	87.30% (n = 110) 12.70% (n = 16)
BMI Mean SD	25.85 ± 3.70
Smoking History (n = 125)	65.60% (n = 82)
Occupation (n=126) Employed Unemployed	55 (43%) 71 (56.35%)
Comorbidities: Hypertension Obesity Diabetes Mellitus Dyslipidemia Renal Disease Cerebrovascular Disease None	89.68% (n = 113) 60.32% (n = 76) 52.38% (n = 66) 42.06% (n = 53) 26.98% (n = 34) 10.32% (n = 13) 1.59% (n = 2)
Mean Laboratory Values: Total cholesterol in mmol/L (n = 37) HDL in mmol/L (n = 37) LDL in mmol/L (n = 37) VLDL in mmol/L (n = 2) Triglycerides in mmol/L (n = 37) FBS in mg/dL (n = 120) HbA1c in % (n = 39)	4.07 ± 1.46 1.06 ± 0.29 2.60 ± 1.22 0.71 ± 0.16 1.50 ± 0.62 117.60 ± 34.14 7.00 ± 1.77
Creatinine (umol/L) Creatinine Clearance (ml/min)	100 ± 28.82 76 ± 20.08
Statin Use (n = 125)	56.80% (n = 71)
Previous MI	37.30% (n = 47)
Previous PCI	17.46% (n = 22)

 

 

Table 2 presents the regional distribution of patients enrolled in the Philhealth ZBen package. Most of the patients were from the national capital region (45%), followed by Calabarzon (38%), Central Luzon (8%) and Bicol region (3%). There were two patients identified from Cagayan Valley (1.6%) and one patient from Northern Mindanao (0.79%).

 

Table 2. Regions of patients enrolled in Philhealth ZBen Package.

REGION	n=126 (100%)
Region I - Ilocos Region	0 (0.00)
Region II - Cagayan Valley	2 (1.59)
Region III - Central Luzon	11 (8.73)
Region IV - A - Calabarzon	48 (38.10)
Region IV - B - Mimaropa	3 (2.38)
Region V - Bicol Region	4 (3.17)
Region VI - Western Visayas	0 (0.00)
Region VII - Central Visayas	0 (0.00)
Region VIII - Eastern Visayas	0 (0.00)
Region IX - Zamboanga Peninsula	0 (0.00)
Region X - Northern Mindanao	1 (0.79)
Region XI - Davao Region	0 (0.00)
REGION	n=126 (100%)
Region I - Ilocos Region	0 (0.00)
Region XII - Soccsksargen	0 (0.00)
Region XIII - Caraga	0 (0.00)
NCR - National Capital Region	57 (45.24)
CAR - Cordillera Administrative Region	0 (0.00)
BARMM - Bangsamoro Autonomous Region in Muslim Mindanao	0 (0.00)

                                                                                        

 

 

One hundred fifteen patients had 2D-echo reports with mean ejection fraction of 61%. Most of the patients have overall preserved ejection fraction. In terms of angiographic findings, most of the patients had three-vessel occlusion (93%) followed by two-vessel occlusion (7%). One-third of the patients had left main involvement (36%).

 

Table 3. Echocardiography and angiographic findings of included patients in Manila Doctors Hospital under the Philhealth ZBen Package from July 2017 to October 2023.

Echocardiography and Angiographic findings	Total   (n = 126, 100%)
Mean Ejection Fraction in % (n = 115)	61.41 ± 11.34
Number of Vessels Occluded: Two Vessels Three Vessels	7.14% (n = 9) 92.85% (n = 117)
Left Main Involvement	35.71% (n = 45)

 

Table 3 presents the clinical risk scores. The mean Syntax I was 35.56 ± 16.44, while the mean Euro score was 1.04 ± 0.82. In terms of mean Syntax II, the mean CABG 4-year mortality was 5.50 ± 6.61. In terms of mean STS scores, the mean risk of operative mortality was noted to be 0.88% ± 0.56, while the mean morbidity was 8.74% ± 3.76.

 

Table 3.1. Clinical risk scores of included patients in Manila Doctors Hospital under the Philhealth ZBen Package from July 2017 to October 2023.

Clinical Risk Scores	Mean ± SD
Mean Syntax I	35.56 ± 16.44
Mean Syntax II   CABG 4-year Mortality	5.50 ± 6.61
Mean Euro Score	1.04 ± 0.82
Mean STS Scores: Operative Mortality in % Morbidity in %	0.88 ± 0.56 8.74 ± 3.76

 

The in-hospital outcomes of included patients were also determined. The most common in-hospital complications include hospital-acquired pneumonia (23%), followed by atrial fibrillation (17%) and BARC type IV (10%). There were no reported cases of stroke, post-CABG MI or death. More than half of the samples did not have in-hospital complications (51%).

Table 4. In-hospital outcomes/complications of patients in Manila Doctors Hospital under the Philhealth ZBen Package from July 2017 to October 2023.

In-Hospital Outcomes	Total   (n = 126, 100%)
Hospital-Acquired Pneumonia	23.02% (n = 29)
Atrial Fibrillation	17.46% (n = 22)
BARC Type IV	10.32% (n = 13)
Acute Kidney Injury	9.52% (n = 12)
Ventricular Tachycardia	3.17% (n = 4)
Supraventricular Tachycardia	0.79% (n = 1)
Stroke	0% (n = 0)
Post CABG MI	0% (n = 0)
Death	0% (n = 0)
None	51.59% (n = 65)

 

Most of the patients stayed for six days (94%). The shortest hospitalization was three days. The ZBen package allows stay of patients until seven days. However, there were five patients who remained for more than 7 days after admission, two of them due to completion of antibiotics for pneumonia.

 

Table 5. Number of hospital days of patients in Manila Doctors Hospital under the Philhealth ZBen Package from July 2017 to October 2023.

Number of Hospital Stay	Total
	(n = 126, 100%)
3 days	2.38% (n=3)
4 days	3.17% (n=4)
5 days	7.14% (n=9)
6 days	74.60% (n=94)
7 days	8.73% (n=11)
8 days	2.38% (n=3)
10 days	0.79% (n=1)
11 days	0.79%(n=1)
Mean SD	6 days

 

 

Discussion

In this study, most of the patients screened under Philhealth ZBen package were males with mean age of 60 years, majority were unemployed and the mean BMI was 25 kg/m², which is classified as obese type 1 under the BMI Asian classification. These findings were almost comparable to the study of Dimalala, et al., where the population were mostly males with mean age of 58 and BMI of 25 kg/m²,¹¹ Most of the patients enrolled in the present study were chronic smokers which could increase the risk for CAD by 51%.^18-19

In this study, hypertension was identified as the most observed comorbidity and these finding were similar to the local study of Raymundo E., et al., and Angelica Dela Cruz, et al.^10,20 The rest of the comorbidities like obesity, diabetes mellitus, dyslipidemia, renal disease and stroke were similar to the study of Canto, et al.²¹

There were 47 (37%) and 22 (17%) patients with a previous history of acute MI and prior percutaneous angioplasty, respectively. But these prior interventions did not affect the good outcome. A finding that was also found in the Nicalau study wherein prior PCI in 13% of cases did not affect outcomes of patients who underwent coronary artery bypass surgery.²²

A greater number of tertiary hospitals accredited by Philhealth ZBenefit program are located in the national capital region (NCR) which could be a factor for influx of patients to the NCR. Most of the patients have preserved ejection fraction (EF) prior to coronary artery bypass procedure with a mean EF of 61%, which could have contributed to the good outcome of post-CABG procedure. In the study of Ni, et al.,²³ patients with low ejection fraction undergoing isolated CABG surgery were at higher risk for postoperative complications and mortality. This risk was not evident in 3.5% of patients with reduced ejection fraction in the present study and all of them were discharged alive.

All patients who underwent the Z benefit package incorporated two scoring systems to evaluate perioperative morbidity and mortality, namely Euroscore and STS score. In this study, the Euroscore ranged from 0.22% to 1.86% and the STS score ranged from 0.32% to 1.44%. Both scores fell within the category of low risk for perioperative morbidity and mortality post CABG. In addition, SYNTAX II scoring system was computed with a mean of 5.50 ± 6.6. This is considered a low score for mortality and that patients would have good prognosis when they undergo CABG.

Most of the patients who had hospital-acquired pneumonia (23%) postoperatively had the following identified risk factors, namely: hypertension, dyslipidemia and chronic smoker. This finding is congruent with the study of Wang, et al.²⁴ There were 22 patients who developed atrial fibrillation and most of them had it in the first 24 hours. Patients who underwent CABG may develop atrial fibrillation and this occurs in 20%-40% of patients after CABG due to reperfusion arrhythmia.^25-26 The other arrhythmias observed were non-sustained ventricular tachycardia (NSVT) in four patients and supraventricular tachycardia (SVT) in one patient. NSVT in all patients was resolved medically. One patient who had SVT while weaning was ongoing from the mechanical ventilator responded to carotid massage.

There were 12 patients (9.5%) who developed acute kidney injury (AKI) postoperatively, but the condition improved with hydration and did not lead to dialysis. According to the 2011 guideline for coronary artery bypass surgery,²⁷ predisposing factors such as diabetes, uncontrolled hypertension and advanced age could contribute to AKI. In this paper, hypertension and diabetes are the first and third most common comorbidities present among patients included in the ZBen package.

In this study, there was no mortality compared to another local study which reported 4.8% mortality.¹⁰ All patients in the study were discharged improved.

 

Conclusion

The results of this study showed the clinical profile and comorbidities of patients who are at-risk to develop CAD and may lead to CABG procedure. The leading cause of CAD was still attributed to hypertension. The main causes of increased length in hospitalization were identified which was hospital-acquired pneumonia and atrial fibrillation. All patients underwent proper screening prior to CABG under the PhilHealth Z Benefit protocol. All patients included in the study had good procedural outcome with no mortality. The results gathered in this study may serve as a reference and baseline data to other institutions who plan to perform CABG under the Z Benefit.

The limitation of the study involved only a small number of population in a single center and patients follow up was only available and limited during the course of hospital stay or admission. It is recommended to conduct a larger-scale, multi-center study involving different institutions that also offer the Z Benefit package to further confirm the above results and enable international comparison. Follow-up of patients after discharge may also be recommended to further assess their functional capacity and possible new development of post-procedural comorbidities.