PMID 35783836

Research
All papers

Short- and Long-Term Effects of High-Intensity Interval Training vs. Moderate-Intensity Continuous Training on Left Ventricular Remodeling in Patients Early After ST-Segment Elevation Myocardial Infarction-The HIIT-EARLY Randomized Controlled Trial

Eser P, Trachsel LD, Marcin T, Herzig D, Freiburghaus I, De Marchi S, Zimmermann AJ, Schmid JP, Wilhelm M

Question

In optimally treated male patients early after STEMI, does 9 weeks of HIIT during cardiac rehabilitation produce better short- and long-term left ventricular remodeling and cardiorespiratory fitness outcomes than isocaloric MICT?

Summary

This randomized controlled trial compared HIIT with isocaloric moderate-intensity continuous training during ambulatory cardiac rehabilitation in male patients early after first STEMI treated with PCI and guideline-directed medical therapy. After a 3-week MICT run-in for familiarization and medication optimization, patients were randomized to 9 weeks of either MICT or a mixed schedule of two HIIT and one MICT session per week. HIIT did not improve left ventricular end-diastolic volume index or peak VO2 more than MICT. At 1-year follow-up, global longitudinal strain improved in MICT but not HIIT, and blood pressure increased more in HIIT, leading the authors to recommend caution with vigorous activity early after STEMI.

Methodology

  • Male patients early after first STEMI treated with primary PCI and enrolled in ambulatory cardiac rehabilitation; 69 analyzed at randomization and end of CR.
  • 73 participants.
  • Cycle ergometer.
  • Work intervals: 4 minutes above second ventilatory threshold, approximately 90-95% peak heart rate.
  • Recovery: 3 minutes active recovery below first ventilatory threshold.
  • Intensity: Borg >=15 for HIIT; workload above second ventilatory threshold.
  • 38 minutes including 10-minute warm-up and 3-minute cool-down.
  • 2 HIIT sessions plus 1 MICT session per week during the 9-week randomized phase.
  • 9-week randomized intervention after 3-week MICT run-in.
  • Single-center prospective randomized controlled trial integrated into a 12-week multidisciplinary ambulatory cardiac rehabilitation program with 1-year follow-up.
  • Left ventricular end-diastolic volume index, Global longitudinal strain, Cardiorespiratory fitness, and Blood pressure and heart rate were tracked.

Outcomes

LVEDVi

LVEDVi increased from randomization to end of CR in both groups, with no significant between-group difference; at 1 year, LVEDVi was not significantly different from randomization in either group.

End-of-CR group x time interaction p = 0.557; 1-year group x time interaction p = 0.297.

No clear change

Global longitudinal strain

GLS had no significant between-group difference at end of CR, but at 1 year MICT improved while HIIT did not, producing a significant group x time interaction.

From randomization to 1-year follow-up, GLS changed by -1.0% (95% CI -1.8 to -0.1) in MICT and 0.3% (-0.5 to 1.2) in HIIT; group x time interaction p = 0.031, adjusted p = 0.021.

Safety concern

Peak VO2

Peak VO2 improved significantly over time in both groups, without significant group x time interactions.

Peak VO2 improved from randomization to 1-year follow-up by 2.4 ml/kg/min (95% CI 1.0 to 3.7) in HIIT and 3.4 ml/kg/min (2.0 to 4.7) in MICT; group x time p = 0.138 at end of CR and p = 0.317 at 1 year.

Improved

Blood pressure

At 1-year follow-up, systolic BP increased in HIIT and was nearly unchanged in MICT, while diastolic BP increased in HIIT and decreased in MICT.

Systolic BP change: HIIT +7.9 mmHg (95% CI 1.5 to 14.3), MICT -0.2 mmHg (-6.4 to 6.1), interaction p = 0.077. Diastolic BP change: HIIT +7.3 mmHg (3.3 to 11.4), MICT -1.3 mmHg (-5.2 to 2.7), interaction p = 0.003.

Safety concern

Biomarkers of myocardial injury and inflammation

There were no significant group x time interactions for high-sensitive troponin T, NT-proBNP, or high-sensitive CRP.

No significant group x time interactions were reported for biomarkers.

No clear change

Insights

  • In early post-STEMI cardiac rehabilitation, HIIT should not be promoted as superior to isocaloric MICT for LV remodeling or fitness.
  • High-risk cardiac HIIT requires medical supervision, conservative exposure, and run-in/familiarization rather than direct consumer translation.
  • Possible long-term GLS and blood pressure signals should temper vigorous-exercise recommendations after STEMI.
  • MICT remains a defensible exercise option when patients prefer it or when HIIT safety is uncertain.

Limitations

  • Target sample size was not reached.
  • Only male patients were included.
  • Physical activity during and after cardiac rehabilitation was not measured.
  • The HIIT arm also included one MICT session per week, so it was not a pure HIIT-only intervention.
  • Adverse event details were not fully described in this article.
  • Findings came from supervised cardiac rehabilitation and may not apply to unsupervised exercise.

Safety

  • One adverse event occurred in each group between randomization and end of CR; the article does not provide event details.
  • The trial used a 3-week MICT run-in for familiarization and safety before HIIT.
  • CPET was monitored by a cardiologist with continuous 12-channel ECG.
  • The authors caution that adverse long-term GLS changes after HIIT warrant caution with vigorous activities early after acute STEMI.