Author + information
- Received August 14, 2018
- Accepted August 21, 2018
- Published online October 17, 2018.
- Faheemullah Beg, MD,
- Colin M. Barker, MD and
- William A. Zoghbi, MD∗ ()
- ↵∗Address for correspondence:
Dr. William A. Zoghbi, Department of Cardiology, Houston Methodist DeBakey Heart and Vascular Center, Houston Methodist Hospital, 6550 Fannin Street, SM1901, Houston, Texas 77030.
The incidence of left main coronary trunk (LMT) compression by an enlarged pulmonary artery (PA) is unknown. Furthermore, there are no guidelines recommending optimal management of this disease entity.
A 54-year-old woman with a history of severe PA hypertension (PAH) presented to our hospital with intermittent atypical chest pain for 2 days. As part of her evaluation, echocardiography showed an estimated PA systolic pressure of 70 mm Hg, and computed tomographic coronary angiography showed stenosis of the LMT ostium and severe dilatation of the PA measuring 5.4 cm (Figure 1). Subsequent transradial selective coronary angiography raised the suspicion of dynamic LMT compression (Figure 2), which was confirmed by intravascular ultrasound (Figure 3). To determine the hemodynamic significance of the dynamic stenosis, we calculated the instantaneous wave-free ratio 3 times and obtained the following measurements: 0.97, 0.98, and 0.96 (Figure 4). These results were consistent with computed tomographic fractional flow reserve determinations (0.94 and 0.91 in the left anterior descending coronary artery). No coronary intervention was hence performed. The patient’s pulmonary hypertension medications were titrated, and her chest pain resolved prior to discharge.
LMT compression may occur in patients with PAH with severely dilated PAs and can be identified with either computed tomographic coronary angiography or selective coronary angiography (1). There are several reports of the safety of stent implantation and resolution of typical angina in such patients (1,2). In patients with LMT compression, atypical symptoms, and no evidence of rest ischemia, further testing is warranted to assess the physiological significance of the stenosis. This is relevant in this context because coronary blood flow and subendocardial perfusion are diastolic events (3,4), and LMT compression from an enlarged PA is a systolic event; hence, not all such lesions lead to ischemia. Exercise stress testing is relatively contraindicated in patients with severe PAH, and vasodilator stress nuclear testing may miss global ischemia in patients with left main disease. Thus, instantaneous wave-free ratio and fractional flow reserve are best suited for evaluating stenosis significance in this setting. To our knowledge, no previous reports of physiological assessment of LMT compression in PAH have been published.
In the present case, measurements of instantaneous wave-free ratio provided objective data on preservation of coronary flow, helped avoid an unnecessary coronary intervention, and direct management to the optimization of PAH treatment with a good outcome.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received August 14, 2018.
- Accepted August 21, 2018.
- 2018 American College of Cardiology Foundation
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