Perfusion scintigraphy and patient selection for lung volume reduction surgery

Abstract

Rationale: It is unclear if lung perfusion can predict response to lung volume reduction surgery (LVRS).

Objectives: To study the role of perfusion scintigraphy in patient selection for LVRS.

Methods: We performed an intention-to-treat analysis of 1,045 of 1,218 patients enrolled in the National Emphysema Treatment Trial who were non-high risk for LVRS and had complete perfusion scintigraphy results at baseline. The median follow-up was 6.0 years. Patients were classified as having upper or non-upper lobe-predominant emphysema on visual examination of the chest computed tomography and high or low exercise capacity on cardiopulmonary exercise testing at baseline. Low upper zone perfusion was defined as less than 20% of total lung perfusion distributed to the upper third of both lungs as measured on perfusion scintigraphy.

Measurements and main results: Among 284 of 1,045 patients with upper lobe-predominant emphysema and low exercise capacity at baseline, the 202 with low upper zone perfusion had lower mortality with LVRS versus medical management (risk ratio [RR], 0.56; P = 0.008) unlike the remaining 82 with high perfusion where mortality was unchanged (RR, 0.97; P = 0.62). Similarly, among 404 of 1,045 patients with upper lobe-predominant emphysema and high exercise capacity, the 278 with low upper zone perfusion had lower mortality with LVRS (RR, 0.70; P = 0.02) unlike the remaining 126 with high perfusion (RR, 1.05; P = 1.00). Among the 357 patients with non-upper lobe-predominant emphysema (75 with low and 282 with high exercise capacity) there was no improvement in survival with LVRS and measurement of upper zone perfusion did not contribute new prognostic information.

Conclusions: Compared with optimal medical management, LVRS reduces mortality in patients with upper lobe-predominant emphysema when there is low rather than high perfusion to the upper lung.

Figure 1.

Kaplan-Meier survival curves after randomization for patients with upper lobe–predominant emphysema (n = 688). Among those with low exercise capacity (panel A1), mortality was lower with lung volume reduction surgery (LVRS) than with optimal medical management (risk ratio [RR], 0.66; P = 0.06). On further classifying patients by upper zone perfusion, this reduction in mortality was greater and was restricted to patients with low upper zone perfusion (panel A2: RR, 0.56; P = 0.008) unlike those with high perfusion (panel A3: RR, 0.97; P = 0.62). Among those with high exercise capacity at baseline (panel B1), reduction in mortality was again greater with LVRS (RR, 0.80; P = 0.04). On further classification by upper zone perfusion this reduction in mortality was restricted to patients with low upper zone perfusion (panel B2: RR, 0.70; P = 0.02), unlike those with high perfusion (panel B3: RR, 1.05; P = 1.00).

Figure 2.

Comparison of frequency of improvement in functional outcomes after randomization to lung volume reduction surgery (LVRS, solid bars) versus optimal medical treatment (OMT, gray bars) for patients with upper lobe–predominant emphysema and low exercise capacity at baseline. Outcomes were consistently better with LVRS through Year 3 (column A1). On further classification by upper zone perfusion, those with low (column A2) rather than high upper zone perfusion (column A3) derived greater benefit from LVRS. These improvements were durable to Year 3 in patients with low but not high upper zone perfusion. SGRQ = St. George's Respiratory Questionnaire; SORQ = University of California at San Diego Shortness of Breath Questionnaire. *Improvement in exercise capacity by at least 10 W; ^†improvement in FEV₁ by at least 100 ml; ^‡improvement in total SGRQ score by at least 8 points; ^§improvement in SOBQ score by at least 5 points from baseline.

Figure 3.

Comparison of frequency of improvement in functional outcomes after randomization to lung volume reduction surgery (LVRS, solid bars) versus optimal medical treatment (OMT, gray bars) for patients with upper lobe–predominant emphysema and high exercise capacity at baseline. Outcomes were better with LVRS through Year 3 after randomization (column B1). On further classification by upper zone perfusion, those with low upper zone perfusion (column B2) rather than high upper zone perfusion (column B3) derived greater benefit from LVRS. These improvements were durable to Year 3 in patients with low but not high upper zone perfusion. *Improvement in exercise capacity by at least 10 W; ^†improvement in FEV₁ by at least 100 ml; ^‡improvement in total SGRQ score by at least 8 points; ^§improvement in SOBQ score by at least 5 points from baseline.

Figure 4.

Flow diagram summarizing the main results of our analysis. Risk ratios (RRs) for mortality were estimated on the basis of the overall mortality in each subgroup after a median follow-up of 6.0 years. The RR for improvement in exercise capacity was assessed by maximal workload achieved on a cycle ergometer 2 years after randomization (less than 10 W vs. at least 10 W).*High risk were patients with FEV₁ not exceeding 20% predicted and either diffusing capacity of carbon monoxide not exceeding 20% predicted or nonheterogeneous distribution of emphysema on computed tomography. ^†Patients with non–upper lobe–predominant emphysema and low exercise capacity can experience more frequent improvement in functional outcomes with lung volume reduction surgery (LVRS) rather than optimal medical management though these are not durable beyond the first 2 years after LVRS, unlike in patients with upper lobe–predominant emphysema. There is no improvement in survival with surgery. In the current analysis upper zone perfusion did not help further define prognosis in this group of patients.