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The COVID-19 pandemic has hit the world in 2020, caused by the spread of SARS-COV-2, which at the end of December was associated with more than 80 million sick people and unfortunately 1.8 million deaths1. Despite this terrible problem, non-communicable diseases continue to claim more than 40 million lives worldwide, particularly those of cardiovascular origin with 18 million2.
At present, there is a lag in the care of patients with heart disease, both in diagnostic and therapeutic procedures, due to this pandemic3. In particular, exercise testing (ET) has been underused or even prohibited, due to the fear of aerosol production by patient's breathing, leaving physicians without a traditional tool with great diagnostic and prognostic power4,5.
Thus, staff in cardiology centers that perform ET, ask patients to wear a mask, although its consequences are hardly being studied6,7. Nevertheless, to date, there is only partial and preliminary information on the effect of the use of these masks on the ergometric performance of an individual.
The objective of the study was to describe the ergometric performance observed when performing exercise tests during the COVID-19 (PANDEMIC-G) pandemic and to highlight the differences with the tests performed before it (NO PANDEMIC).
Methods
A cross-sectional study was carried out. Thus, we have described the patient referrals and ET performed in the “real world” during the COVID-19 pandemic (PANDEMIC-G, March-December 2020), and we have remarked the differences with the usual work performed in the same period, before the pandemic (NO PANDEMIC group).
The independent variable was the presence of the COVID-19 pandemic, with characteristics such as several epidemiological restrictions and the mandatory use of masks.
Each patient from PANDEMIC-G underwent a biological triage composed of a questionnaire looking to detect COVID symptoms, body temperature measurement, heart rate, and digital oximetry. All patients of PANDEMIC-G wore N95 masks throughout the ET and staff surveyed its proper use, ensuring that mask partially collapsed during patient inspiration. Beyond that, all exercise tests were symptom limited and carried out in a similar way as reported elsewhere8.
Variables are presented as frequency (percentage), mean (standard deviation), or median (interquartile interval) according to their type and distribution. Differences were studied using the Chi-square test, the Student's t-test for independent variables, or the Wilcoxon rank test, as appropriate. All p < 0.05 were considered stochastically significant.
Results
A total of 361 stress tests were studied, 209 (58%) belonging to NO PANDEMIC group and 152 (42%) to PANDEMIC-G, showing a decrease of 27% in 2020 compared to 2019. Demographic variables are shown in table 1. The indications for the exercise test were as follows: risk stratification in patients with cardiovascular disease or pre-participation sports evaluation in athletes. All tests were limited by symptoms and patients with heart disease performed a modified Balke ramp protocol, while athletes underwent a Bruce ramp test. For all subjects, the most common reasons to stop exercise test were fatigue (n = 165, 43%) and dyspnea (n = 125, 35%). However, the ratio between dyspnea and fatigue was different between groups, where 117 (77%) tests were suspended due to dyspnea in in PANDEMIC-G versus 8 (4%) in NO PANDEMIC group, with an OR= 6.3 (95% CI, 4.6-8.6, p < 0.001 analogously), ET suspension due to muscular fatigue was 88% (n = 178) in NO PANDEMIC and 16% (n = 24) in PANDEMIC-G, p < 0.001. Other less common causes of suspension were claudication (n= 12, 3%), exercise-related hypotension (n= 8, 2%), and ventricular tachycardia (n= 12, 3%), among others. No mayor adverse outcome occurred.
Table 1 Demographics
| n (%), mean (SD) | All | No pandemic | Pandemic-G | p value |
|---|---|---|---|---|
| Subjects | 361 (100%) | 209 (58%) | 152 (42%) | < 0.05 |
| Gender | F (67, 19%), M (294, 81%) | F (47, 22%), M (162, 78%) | F (20, 19%), M (132, 81%) | < 0.05 |
| Age (y) | 46.8 ± 20 | 48 ± 20 | 45 ± 21 | ns |
| Weight (kg) | 70.6 ± 15 | 70 ± 17 | 72 ± 14 | ns |
| Height (cm) | 165 ± 13 | 164 ± 14 | 167 ± 11 | ns |
| BMI | 25.6 ± 5 | 25.5 ± 5 | 25.8 ± 5 | ns |
| Diagnosis | ||||
| IHD | 221 (61%) | 136 (65%) | 85 (56%) | ns |
| Athl | 81 (22%) | 29 (14%) | 52 (34%) | < 0.01 |
| CHD | 38 (11%) | 26 (12%) | 12 (8%) | ns |
| VHD | 6 (2%) | 4 (2%) | 2 (1%) | ns |
| Other | 15 (4%) | 14 (7%) | 1 (1%) | < 0.05 |
| Smoking | 101 (28%) | 62 (30%) | 39 (26%) | ns |
| Diabetes | 69 (19%) | 41 (20%) | 28 (18%) | ns |
| Hypertension | 134 (37%) | 80 (38%) | 54 (36%) | ns |
| Dyslipidemia | 230 (64%) | 143 (65%) | 87 (57%) | < 0.05 |
| Beta-blocker | 223 (65%) | 145 (73%) | 78 (53%) | < 0.01 |
| ACEi/ATIIi | 232 (67%) | 147 (75%) | 85 (58%) | < 0.01 |
| Digoxin | 4 (1.3%) | 2 (1.2%) | 2 (1.5%) | ns |
| Calcium channel blockers | 26 (9%) | 15 (9%) | 11 (8%) | ns |
| Statins | 224 (64%) | 141(70%) | 83 (56%) | < 0.01 |
| Diuretics | 136 (38%) | 91 (43%) | 45 (30%) | < 0.01 |
| Aspirin | 223 (65%) | 140 (70%) | 83 (56%) | < 0.05 |
| LVEF | 53 (12) | 52 (13) | 55 (10) | < 0.05 |
| SPAP | 33 (12) | 36 (14) | 29(8) | < 0.05 |
F: female; M: male; BMI: body max index; IHD: ischemic heart disease; Athl: athletic evaluation; CHD: congenital heart disease; VHD: valvular heart disease;
ACEi/ATIIi: angiotensin-converting enzyme and angiotensin II receptor inhibitors; LVEF: left ventricle ejection fraction; SPAP: systolic pulmonary arterial pressure.
Table 2 shows the comparison of the ergometric behavior between the individuals of both groups. Heart rate behavior, including baseline resting, maximum effort, and recovery phases, did not show significant changes between groups. However, the percentage of the maximum heart rate calculated for age was significantly lower for patients in PANDEMIC-G (78 ± 12% vs. 81 ± 14%, p < 0.05), and the chronotropic index was also diminished (6.8 ± 2 vs. 7.5 ± 3 bpm/MET, p < 0.05).
Table 2 Comparison of the ergometric performance between no pandemic and Pandemic-G patients. This table shows patients performance at rest and exercise. No statistical differences were observed in maximal exercise tolerance, but systolic blood pressure was stochastically higher in patients that wore mask
| n (%), mean (SD) | All | No pandemic | Pandemic-G | p value |
|---|---|---|---|---|
| Subjects | 361 (100%) | 209 (58%) | 152 (42%) | |
| Rest HR (bpm) | 72 ± 15 | 72 ± 15 | 73 ± 15 | ns |
| Rest SBP (mmHg) | 108 ± 16 | 107 ± 17 | 111 ± 15 | < 0.01 |
| Rest DBP (mmHg) | 71 ± 11 | 69 ± 9 | 72 ± 12 | < 0.05 |
| Rest DP (mmHg*bpm¨1000) | 7.8 ± 1.9 | 7.6 ± 1.9 | 8.1 ± 1.9 | < 0.05 |
| Max HR (bpm) | 136 ± 31 | 136 ± 29 | 137 ± 33 | ns |
| Max SBP (mmHg) | 138 ± 27 | 133 ± 27 | 145 ± 27 | < 0.001 |
| Max DBP (mmHg) | 78 ± 10 | 77 ± 11 | 78 ± 10 | ns |
| Max DP (mmHg*bpm*1000) | 19.3 ± 7 | 18.5 ± 6.5 | 20.4 ± 7.9 | < 0.05 |
| Recov1-HR (bpm) | 119 ± 27 | 119 ± 26 | 120 ± 28 | ns |
| Recov1-SBP (mmHg) | 133 ± 24 | 128 ± 25 | 139 ± 21 | < 0.001 |
| Recov1-DBP (mmHg) | 76 ± 10 | 75 ± 10 | 76 ± 10 | ns |
| Ischemia (n, %) | 19 (5.3) | 18 (8.6) | 1 (0.7) | |
| ST changes (mm) | (-1.3) ± 0.5 | (-1) ± 4 | (-1.4) ± 5 | ns |
| Arrhythmia | 172 (48%) | 100 (48%) | 72 (47%) | ns |
| Frequent premature ventricular complexes | 37 (10%) | 27 (13%) | 10 (6%) | < 0.05 |
| Atrial fibrillation | 5 (1.4%) | 3 (1.4%) | 2 (1.3%) | ns |
| Ventricular tachycardia | 14 (3.9%) | 11 (5.3%) | 3 (2%) | ns |
| Veteran score | (-6) ± 7 | 5.2 ± 7 | 7.1 ± 6 | < 0.05 |
| Duke score | 8 ± 5 | 7.9 ± 4 | 8.5 ± 5.3 | ns |
| Max HR (reached %) | 79 ± 14 | 81 ± 14 | 78 ± 12 | < 0.05 |
| METs-Max | 9.4 ± 4 | 9.2 ± 4 | 9.6 ± 4 | ns |
| Reached VO2max (%) | 97 ± 34 | 99 ± 37 | 93 ± 28 | ns |
| MVO2 max (mlO2/100g) | 20.7 ± 10 | 19.6 ± 9 | 22.2 ± 11 | < 0.05 |
| Max. oxygen pulse | 16.4 ± 6 | 15.7 ± 6 | 17.3 ± 6 | < 0.05 |
| Pressure response (mmHg/MET) | 3 ± 2 | 2.8 ± 2.1 | 3.2 ± 1.9 | ns |
| ESPI | 1.3 ± 0.23 | 1.26 ± 0.2 | 1.31 ± 0.24 | < 0.05 |
| RSPI | 0.97 ± 0.09 | 0.97 ± 0.08 | 0.97 ± 0.11 | ns |
| CI (bpm/MET) | 7.2 ± 3 | 7.5 ± 3 | 6.8 ± 2 | < 0.05 |
| RHR (bpm) | 64 ± 27 | 64 ± 26 | 64 ± 27 | ns |
| HRR1(bpm) | 17 ± 11 | 17 ± 11 | 17 ± 10 | ns |
| ECP (*1000) | 13.7 ± 6 | 13.5 ± 7 | 13.8 ± 6 | ns |
HR: heart rate; SBP: systolic blood pressure; DP: double product; VO2max: maximal oxygen uptake; MVO2max: maximal myocardial oxygen uptake; ESPI: exertional systolic pressure index; RSPI: recovery systolic pressure index; CI: chronotropic index; RHR: reserve heart rate; HRR1: heart rate recovery 1st min; ECP: exercise cardiac power.
The most evident ergometric differences were observed in the systemic blood pressure behavior. Along every phase of ET, systolic blood pressure showed statistically higher values for PANDEMIC-G compared to the NO PANDEMIC (Fig. 1). Exertional blood pressure index was also higher in PANDEMIC-G than NO PANDEMIC (1.31 ± 0.24 vs. 1.26 ± 0.2, p < 0.05). Likewise, the double product and myocardial oxygen uptake in the patients of PANDEMIC-G were higher compared to the NO PANDEMIC group.
Figure 1 This graphic shows how systolic blood pressure levels are higher in patients that performed a cardiovascular exercise testing during the COVID pandemic.
The maximum exercise tolerance did not show significant differences between groups (p = ns) and the maximal effort oxygen pulse was statistically higher in PANDEMIC-G (17.3 ± 6 vs. 15.7 ± 6, p < 0.05). The Veterans score performed better in the NO PANDEMIC group than in PANDEMIC-G (5.2 ± 7 vs. 7.1 ± 6, p < 0.05).
Discussion
This study shows the ergometric performance of a group of patients who performed an exercise test in the COVID era with some peculiarities such as the use of face masks. The first finding was the lower number of ETs carried out during 2020, problem that has been widely published by various authors as an indirect consequence of the COVID-19 pandemic9-11.
In relation to the heart rate behavior, our findings show a habitual behavior of chronotropism, observations that agree with those found by Epstein et al. who performed maximal ET in a group of 16 healthy volunteers with and without face mask. These investigators found elevated levels of end-tidal carbon dioxide level when subjects wore a face mask12.
In patients who underwent exercise tests during the pandemic, blood pressure levels were higher than the group of patients who performed their exercise tests before the pandemic. One explanation for the systemic increases in blood pressure while patients exercised wearing a mask could be hypercapnia, which is associated with the rebreathing of carbon dioxide trapped within the mask and the concomitant increase in space physiological dead. This phenomenon has already been described in pathologies such as sleep apnea-hypopnea syndrome13. This observation does not accord with Epstein et al. that reported no significant changes in blood pressure at maximal effort. Another variable that could be associated with high blood pressure values is the increase in inspiratory and expiratory effort when breathing through a mask14.
Limitations
The study is not intended to present a historical cohort and cannot be a controlled clinical trial, but rather to describe the particularities of EPs performed during a single moment of the human race (PANDEMIC-G) and to refer to the usual findings observed before it (NO PANDEMIC). A major limitation is not having a randomized control group, but “real-world” circumstances and the restrictions of the pandemic did not make this possible. In the future, a controlled clinical trial may be required to describe the specific effect of wearing masks during an exercise test. Another limitation is the heterogeneity in the diagnoses of the patients, mainly because it is an emerging study and in the real world.
Conducting observations on patients during this time of restrictions, particularly the use of face masks, can establish research lines that in the future will expand knowledge in patients with respiratory diseases and obesity, even if the pandemic had already ended.
Conclusions
In the COVID period, a significantly lower number of exercise tests were performed. In addition, ET using face masks was associated with higher systolic blood pressure values and an increased number of tests suspended due to dyspnea. Maximum exercise tolerance did not show significant differences between both groups (p = ns).
