Case 2

Published on 02/03/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1216 times

Case 2

A 45-year-old man is urged by his wife to have a cardiac risk assessment. He has no cardiac symptoms.

His only coronary risk factor is dyslipidemia (LDL = 143 mg/dL, HDL = 35 mg/dL).

National Cholesterol Education Program (NCEP) Adult Treatment Panel III

image

According to the NCEP Adult Treatment Panel III, he has two “non-LDL” risk factors. The next step is to determine his Framingham Risk Score (FRS).

Framingham Risk Score

Age: 45
Gender: Male
Total Cholesterol: 240 mg/dL
HDL Cholesterol: 35 mg/dL
Smoker: No
Systolic BP: 135 mm Hg
BP Medication: No
Risk Score: 6% over 10 years (low risk)

NCEP Adult Treatment Panel III

image

Because his FRS is “low risk” and his target LDL is < 160 mg/dL, no treatment with cholesterol-lowering medications would be recommended. No other diagnostic testing is recommended.

Proposed Management Strategy for Asymptomatic Patients

image

Because his FRS is “low risk,” the proposed treatment algorithm would suggest that he be managed according to primary prevention guidelines.

However, the patient’s wife requested that he have a coronary calcium score (CCS). According to published appropriateness criteria, CCS would be considered inappropriate (median score = 1) in this man with a low (<10% event rate over 10 years) FRS. However, at the urging of his wife, the CCS was obtained. (Refer to Hendel et al. J Am Coll Cardiol 48:1475–1497, 2006.)

Coronary Calcium Score

image

Calcified plaque was detected in the LAD (137) and RCA (301), with a total CCS of 438 (>90th percentile for age and gender).

Clinical Questions

1. Does he have coronary artery disease (CAD), and would he benefit from aggressive risk-factor modification? Yes. Despite his low-risk FRS, the presence of extensive coronary calcification confirms the presence of atherosclerosis and warrants aggressive risk-factor modification according to secondary prevention guidelines.
2. Would he benefit from coronary revascularization? At this point, we cannot answer this question. The presence of coronary atherosclerosis by CCS does not imply the presence of flow-limiting CAD that might benefit from revascularization.

Proposed Management Strategy for Asymptomatic Patients

image

According to the proposed management strategy for asymptomatic patients, the finding of an elevated CCS (>400 or >90th percentile for age and gender) is an appropriate indication for stress MPI (median appropriateness score = 7.5). Regardless of the stress MPI results, his risk factors should be managed aggressively according to secondary prevention guidelines.

Exercise SPECT MPI

He exercised on a Bruce protocol for 14:30 minutes (17 METs). No symptoms were reported, and his hemodynamic response was normal. He had 1 mm horizontal ST depression at peak exercise that resolved <1 minute into recovery.

Duke Treadmill Score

(14 min) − (5 × 1 mm) − (4 × 0 index*) = +9

Score Risk 5-yr Survival
<−10 High <75%
−10 to 4 Intermediate 95%
>4 Low 99%

Despite the presence of exercise-induced ST-segment depression, his excellent exercise capacity and lack of anginal symptoms resulted in a computed Duke treadmill score of +9 (>4 = low risk).

SPECT Images

image

On poststress images, there was a mild to moderate focal perfusion defect noted in the inferior and inferobasilar regions. Resting images demonstrated defect reversibility consistent with inducible ischemia. Interpretation was complicated by GI tracer interference.

Gated SPECT Images

image

On poststress gated SPECT images, there was normal myocardial systolic thickening in all myocardial regions, with a normal computed left ventricular ejection fraction of 67%.

ASNC Management Strategy for Asymptomatic Patients

image

This exercise stress SPECT MPI study would be classified as mildly abnormal based on the mild (localized) inducible ischemia at a high exercise workload and normal left ventricular systolic function. According to the proposed management algorithm for asymptomatic patients, medical therapy is the recommended treatment for patients with mildly abnormal MPI studies.

Recommendations

1. Aggressive medical therapy (secondary prevention guidelines) was recommended.
2. Coronary angiography could be considered if the patient develops angina symptoms or shows evidence of progression of disease on subsequent testing.

However, the patient’s wife convinced his cardiologist to perform coronary angiography.

Coronary Angiography

• Left main: normal
• LAD: mild diffuse plaque
• LCX: normal
• RCA: 60% proximal, 70% mid

The coronary angiogram demonstrated mild diffuse atheromatous plaque in the LAD and sequential moderate (60% proximal and 70% mid) stenoses in the RCA. The coronary angiogram results were consistent with the CCS (plaque was confirmed in the LAD and RCA territories). The angiogram results were also consistent with the SPECT MPI study (mild inferior and inferobasilar ischemia at a high exercise workload is consistent with moderate sequential stenoses in the RCA). Given the absence of angina and the excellent exercise capacity, no coronary revascularization was performed, and medical therapy was recommended.

Teaching Points (See Chapters 20 and 22)

This case demonstrates the complementary roles of MPI and CCS.

The CCS demonstrated the presence of coronary atherosclerosis and guided the aggressiveness of medical therapy for his coronary risk factors. The invasive coronary angiogram did not add additional information in this regard. CCS is the test of choice when the clinical question is, “Does this patient have coronary atherosclerosis and would he/she benefit from aggressive risk-factor modification?”

The MPI study demonstrated mild inducible ischemia at a high exercise workload, suggesting the presence of flow-limiting coronary stenosis but a favorable prognosis. The invasive coronary angiogram confirmed the MPI findings. MPI is the test of choice when the clinical question is, “Would this patient derive benefit from coronary revascularization?”

The CCS and MPI results provide complementary information and are used to answer distinct clinical questions.

* Angina index: 0 = none, 1 = nonlimiting, 2 = limiting

Related posts:

Case 27 Case 28 PET/CT and SPECT/CT Hybrid Imaging Case 11 Imaging for Preoperative Risk Stratification Overview of Tracer Kinetics and Cellular Mechanisms of Uptake