MPS patient numbers and data from cardiology
Table 1 lists the numbers of MPS patients recorded in the surveys, the estimated total number of patients after adjustment with the NASHIP statistics, and data of the participating centres. Based the NASHIP data, clearly more than 50% of all MPS were included in all surveys.
Table 1: MPS procedures
|
2012
|
2015
|
2018
|
2021
|
MPS patients (survey)
|
105,941
|
121,939
|
145,930
|
133,057
|
% total MPS patients
|
61
|
64
|
67
|
54
|
Total MPS patients*
|
173,941
|
190,530
|
217,806
|
246,402
|
Number of centres
|
278
|
268
|
291
|
218
|
Mean MPS/centre
|
381
|
455
|
502
|
610
|
< 50 MPS/year
|
21%
|
18%
|
15%
|
11%
|
> 1000 MPS/year
|
10%
|
12%
|
15%
|
18%
|
* Estimate based on the NASHIP (National Association of Statutory Health Insurance Physicians) statistics
Figure 1 shows the time course of the NASHIP counts of the fee schedule items 17330 (stress MPS) and 17331 (rest MPS) from 2012 to 2021. The item stress MPS increased by 43% and the item rest MPS by 41%.
During the period under review, mean and median MPS examinations per centre increased substantially. There was a decrease in centres with <50 MPS/year (<1 MPS/week) and, on the other hand, a continuous increase in those with >1000 MPS/ (>4 MPS/d) over time (Table 1).
A total of 110 centres provided data to all surveys between 2012 and 2021. They demonstrated a 47% increase in their MPS patients from 59,728 (2012) to 87,973 (2021).
The number of ICA, interventions, and ratios is shown in Table 2. ICA figures fluctuated. The ICA/MPS ratio was decreasing after 2015. Revascularisation numbers varied with those of ICA. Their ratio remained constant.
Table 2: Invasive coronary angiographies (ICA), interventions and MPS ratios
|
|
|
2012
|
2015
|
2018
|
2021
|
ICA
|
857,688
|
911,841
|
867,138
|
798,751*
|
ICA/MPS
|
4.0
|
4.5
|
4.0
|
3.2
|
Revascularisation (total)
|
392,473
|
416,979
|
411,110
|
371,357*
|
PCI
|
337,171
|
365,038
|
366,840
|
333,373*
|
Bypass
|
55,302
|
51,941
|
44,270
|
37,984*
|
Revascularisation/ICA
|
0.46
|
0.46
|
0.47
|
0.46
|
* Data refer to 2020. More recent data not available at the time of writing the manuscript.
Changes in referral behaviour and competitive methods
In all surveys, participants were asked to assess their individual development of MPS examinations and, in case of a decline, the causally suspected competitive modality or modalities.
The assessments from 2012 to 2021 varied significantly (P<0.001) and are depicted in Figure 2. Since 2012, there has been a steady increase in centre with rising MPS examinations and a constant proportion of institutions with unchanged numbers. Correspondingly, the proportion of centres with declining numbers decreased.
The presumed reasons for fewer MPS patients are shown in Figure 3. A single dominant competitive modality was not discernible. All in all, the other imaging methods represented the greatest competition. The Covid-19 pandemia only played a minor role.
MPS referrals
The MPS referral structure is illustrated in Figure 4. Outpatient care cardiologists represented the most important referral group. They showed a significant increase from 2012 to 2015 (P=0.003) and a constant proportion in the further course. Primary care physicians showed a mild increase which was significant from 2012 to 2015 (P<0.001). Referrals from other physicians and from in-patient ward physicians mildly fluctuated. Formally, there was a significant increase in the group of other physicians from 2012 to 2015 (P=0.001).
MPS study protocols
Utilisation of the different MPS protocols is depicted in Figure 5. In the surveys, Tc-99m-MIBi or Tc-99m-tetrofosmin were not asked separately.
Mostly, 2-day protocols were used. Over time, only insignificant changes with a mild increase in 1-day (stress and rest) and stress-only protocols could be observed. Thallium has been abandoned since 2018.
Stress techniques
Figure 6 shows the utilisation of the different stress techniques. The use of exercise stress decreased steadily. Formally, the decline was only insignificant from 2015 to 2018 (2012-2015 P=0.006; 2015-2018 P=0.133; 2018-2021 P=0.01). In 2021, exercise stress was replaced for the first time by pharmacological stress as the most frequent stress modality. Regadenoson showed a rapid and significant increase (2012-2015, P<0.001; 2015-2018, P=0.002; 2018-2021, P=0.001) and has been ahead of adenosine since 2018. The adenosine proportion remained constant. Dipyridamole is not licensed in Germany as an MPS stressor and was no longer queried in 2021. Dobutamine as a 2nd choice stress agent was used in very rare cases with a declining proportion.
Camera systems and attenuation correction
Camera systems (Figure 7) and attenuation correction data (Table 3) were available from 2015 to 2021. Statistics of the camera systems used revealed significant differences (P=0.019) over time. Single-head cameras were still utilised in a few centres (3%). In 2021, they examined only 1.2% of the patients. The number of centres with SPECT-CT systems was steadily growing, whereas those with CZT systems increased only slightly. The latter performed about 19% of all MPS in the queries. Centres with dedicated cardiac cameras or with more than one camera system for MPS imaging were rather the exception.
Table 3: Attenuation correction in MPS
|
2015
|
2018
|
2021
|
Prone/supine imaging
|
11%
|
10%
|
8%
|
Transmission sources
|
6%
|
3%
|
1%
|
CT-based AC
|
11%
|
20%
|
30%
|
> one AC method available
|
1%
|
1%
|
1%
|
No attenuation correction
|
71%
|
66%
|
60%
|
Patients studied with AC*
|
25%
|
26%
|
33%
|
The values in the upper 5 lines refer to the number of responding centres.
* Changes between the surveys were not significant.
The number of centres using attenuation correction for MPS imaging was increasing. In 2021 at least one third of all MPS patients were studied with an attenuation correction procedure. Statistically the chances were not significant (P=0.175). The main attenuation correction method was CT. Transmission sources for attenuation correction were decreasing and played a marginal role in the last survey.
Gated SPECT and quantitative scoring
The proportion of MPS patients acquired with gated SPECT instead of ungated SPECT was increasing steadily, most recently reaching nearly 90% (Table 4). Statistically the changes were not significant.
Table 4: MPS imaging as gated SPECT
|
2012
|
2015
|
2018
|
2021
|
Gated stress
|
73%
|
80%
|
86%
|
89%
|
Gated rest
|
70%
|
78%
|
87%
|
88%
|
Gated both
|
67%
|
76%
|
83%
|
87%
|
Data represent percentages of MPS patients with gated SPECT. Changes between the surveys were not significant.
The percentages of centres performing a regular, an intermediate, or no quantification of myocardial perfusion with scores are listed in Table 5.
Table 5: Utilisation of perfusion scores
|
2012
|
2015
|
2018
|
2021
|
Regular
|
35%
|
53%
|
67%
|
72%
|
Intermediate
|
23%
|
23%
|
17%
|
15%
|
Never
|
41%
|
24%
|
16%
|
13%
|
Data represent percentages of centres.
The data show an increasing acceptance (P<0.001), with a doubling from 2012 to 2021. Nevertheless, a low proportion (13%) of centres not scoring remained. In 2021, they examined only 6.4% of the patients.